•
CAIN , I
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WORKSHOP PRACTICE SERIES from Argus Books 8 . Sheet Metal Work
I . Hardenin& Tempering ilnd
R.E. Wakeford
Hear Trea tment
Tuba l Cain 2. Vertical Milling in the Home
Workshop Arnold Tnrop 3. Screwcutting in the L.lthe Martin Cleeve
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4 . Foundrywork for tile Amateur B.T. Aspin
5. Milling Operations in the Lathe Tubal Cain 6. Me,lSuring and MarkinB Metals
Ivan law
9 . Soldering iJnd Brazing Tubal Cain 10 . Saw's and Sclwing lan Bradley 11 ffee/rop/alioS J. Poyner 12 .
Drills. Taps and Dies Tubal Cam
15 . Workholding in the Lathe Tubal Cain 16. ElectriC Motors
V.l. Cox • 17 . Cear~ and Gear Cutting I. Law 18 . Basic Benchwork
les Oldtidge 19 . Spring Des/g" imd ManufiJcture
Tubal Cain 20. Metalwork and Machining
13 Workshop Drawing
Hints and Tips
Tubal Cain
lan Bradley
I' Making Small Workshop Tools
7. The Art of Weldmg
S. Bray
W .A . Vau!te
•
1.
Hardening, Tempering and Heat Treatment
In this valuable book Tubal Cain takes the reader beyond the superficial or the simply practical with explanations of the composition of steel, its additives, and the effects of different temperatures on its constituents. With a grasp of what changes are actually taking place in the metal the care needed in following the practical processes described becomes understandable and will lead to better and more consistent results. Flame, salt bath and furnace heating are detailed, with information on accurate measurement or recognition of temperature levels . For the average small workshop operative or mode l engineer the discourses on tool material , hardening and tempering will be of most use, and in th is connection this book rep laces the earlier "Hardening and Tempering Engineers' Tools", providing a broader-based, more detailed and Lip to date examination of the subject.
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IS BN 0-
9
242-837-5
HARDENING, TEMPERING AND HEAT TREATMENT for model engineers
• Tubal Cain
I
ARGUS BOOKS
ArV"" 1 0<+' ArIJUll H _ _
H .,. H....-.:I HI'tI.".,....,. HP2 7ST W~
Contents • Ch.pl • • 1 Ch.Iopl lt 2 Cto.oop l .. 3 Ch.IoPllt 4 Ch.Ioptl< 5 Ch.IoPll<' Ch.Iopl.. 7 Ch.Ioptl< 8 Cl'uop'1<9 Chlptl<10 AppI
Cl ~ IIooU lid HI84 Steond
"'PI.""" Im 1987, 1988. 1990
R~,n'ood
A~ndi.
All roghll , .... , No PM of lh.. JlUbhCl" """"" t.. _oducood in IiIV loom. by 11"111. l>I>otou'." ..... mOCf
Of
"'v 01'* _ .. w~hou' won.. "................ _
~.-
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4
I,on 11< SIHI Principles 01 the H"lIttni"ll P,oeen Hea'ing.nd Quenching in PtK,kI T....,pe,ing Hea'ing Elluiprr.-m Cneto~.den,ng
Om.. Hu, T, •• ' ........ ' P,oe •• " . Thoo M ..............' o' H.'cIo .... Home eormructoon 01 F.., _ Slfery Pteau,ions n...moc:oul>lH.nd Pyrome,," Carbon Sleel Cunlng ToolI Bri,ish SlInd.,d 5 1•• ' 5pe<:ific"k>n Numbets HBtdnBSS Convtt,.ionl
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90
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CHAPTER 1
Iron & Steel • If "Know you. Enemv" is p.udent coun ....1 10< Ihe soldier. Ihen e«ually SO musl be "Know vou. Male.lal." for Ihe e"9in ..... model a. olhefWise. Importanl enoullh wh"" Ih. malerial. a.e 10 be cuI Or formed. buI e.en mOre SO when we propose 10 all.r Ihel. characI •• islics. And lhere can be few wch alle'&lloo$ so • • lrem. 11 when we COnV8rt a ,.Iallyely 0011 and ductile maler;al into one which is hard enough 10 aCIII. cuning 1001. So. I make no excu .... lor Ihis inilial 8)(p10<81ion of Ihe nalure 01 i,on and 51 ....1. You can "skip" Ihe chaple. if vou wish - il may be Ihet ;1 lells you nolhing new. and could well ... em la be Irrelevant if all vou wanl 10 tIo i, 10 ha.den a scribe, POin!1 Bulla begIn 81 11'1. beginning is always
whOIlV Iron.) The eotnmon ore. ara in Ihe fOfm 01 o.ides. some. nolablv Haema , i'e. ~lmoSl 90% le.n.:: o.ide wnilsl otne1$ may contain as IInle as 25%. 11'1. remainder being lime Or s;lica based stone. Olhe. type. of 0<8 CDnlain i,on Carbonlles. Ind a .ery abundanl "",ree Is Iron Pyriles mos~IIV i.on tulphide and seldom uMd in the manulaclure of iron di.eclly, I,on is ",,"acled from the 0", in a Blast Furnace - Fig. 1. Even in early limes Ihese we,. I.,ga Sltuclures. 001 ladav Ihey are huga. The "hearth" al Ihe bonom is 45 feet across _ and lha stad 100 fael Of more ln heigh,. whh anolhe. 100 feel 01 "lop hamper" above. A medium sl. ad /u,n&ce will COIllaln 50.000 cu. feel of male.l., .fld will "ma ke" 9000 Ions! week: Fig 2. Tha 1.,ge.1 furnace In this counlry is designed lor 10.000 IonS per dlJY• • od keeping I1 led wilh rlw ma lerial. i, a major parr 01 ,he pia", O(Ief1ltOfS concern I Thew raw mal.,,.I, are iron 0<., <:Oke l,he luaf) and limestone to ltel as I "'lux" SO Ihallhe slony mine, in the ore mlJY be su/ficienllv fluid when meiled. These malerials. blended and sinlered ;nlo e uniform sl.a afld composition • • r. fMf In I1 Ihs lop. Prehealed eir is blown In at Ihs bollom. Ihrough ,he .. Iuye'e .... aoo this air forms by far Ihe I"gesl mass 01 mllerlal
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luelllU. BV ,h",ime 1h" "burden" r.aches
Ill .. lowe, part ol lhe lurn...,., Ihe Ilu> and stone ..,ill begin 10 combine 10 form a slag
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used. Though nomin~11y ··fr... •• IllIn to be compressed 10 from 30 10 45 Ib/sq.in. and hee,ed 10 .,oun
""p.moll. "stov. .'· to achieve \ha ,equirMl lamper"l,,"" Combustion 01 1he coke 81 ,h" hnnll
which melt. and runs down through 1he coke. Slightly lower down 1he iron also melts. B01h slag and iron collect in the
hea'lh ..... ith the lIIag lloating on top. At pe.iodic intervals Ihe slag i. lapped olf Ih,ough one IIole and the i,on /,om anothe •• being collected in .ail ..... ay l&dlus. the /o.me, being used lor road metal or cement making and the iron eithe< casl inlo "pigs" for lhe foundry or taken, molten. 10 the Bleelworks. Outing the final pan 01 .h;' pn:>ce-S' Ihe molten iron Is in dose conlact ..... "h very IIot coke and ..... ill absorb up to 4% of cafbon. (This m~ not sound much unlil I lell \'<>U that. chunk of iron 0)1 22 inch cube will conlain IS much car\xln as I sac~ of cokell The importanl thing 10 apprsCiete al Ihi. Stage is lhat lhe iron and carbon lorm a sO/ulio:>n. jusl like the wge' in \'<>Ur lea. Aft.r passlr>glhrough a paSIV stage whit", cooling the iron $Olidifiss at about 1130· C. end we r>OW have a so/id $Olulion 01 iron IFs"itel and carbon . bm wilh $Ome of 'he carbon r>OW combining 10 form an I,on carbide. How...,., •. 85 lhe melal cool. funhe. It. capacily 10 diuolve carbon diminishes. and $Ome '·Ir.s·· carbon appear, .1 Ihs grllin boundaries as graph;'e. The final sla,e does depend some ..... h.t on IIow 1...1
the melal ha. <:oolad. bUI ,n. "gray" cas' i"'" which we use .... iII appear under I;'" microsCOpe I. small agglomerations 19"insl or iron carblda and Ferrite Cl"{S1I15. surroundad by flakes of graphila. (Fig.311f Ihe cooling is rapid then more of lhe carbon .... ill remain as carbide and lhe metal .... ill be while. and harder. Henc, lI>e oc:usional "'hard spot"" al Ihe cor"". 01 a thin <;IIs,ing; the malal hes cooled too fu,. I"'" in th's form is very useful; il can be o;8SI Into complex Shope. and is vary S\I'O-ng in compression. Bu, il is less Strong in lansion and rather brill le; II cannol be' lMnt or fo'ged. It is useless for edged 1001. and for many m8chine pans. Very early in I"," history 01 metals means ..... ere sough,
10 render "'I"","' mOre ductile. The ... led 10 'he manufaclure of W~OUGHT IRON. using a procass wl>ich remOVad moll of lhe carbon from tha Iron made In the bl •• ,-furnll<:a. Pig"ron was melted In a C081 0< ool< ....Ii'ed furnace !Fjg.4J lined .... ilh male.ial ~ontaining a large '""",nl of iron oxide. A cenl;n amount d' o.ide .... as also charged with Ihe pig-lron. AboUI 4 c..... l ..... as maltad " e&d'l n..! and ..... han molten .... n. 01 course. In Intima'e COntll<:! .... ill> Ihe oo.idel- The
flg."_" ",,_ .... _ .... _F, '.' _ _ "'","._5,"",'. . _,· ,s.." ...... ' - _ _
--"''''''''*_."" ..,,-..., .. - ....- _ .......__'''"-_ ..........''''-_ .... "_.c ......,."',."Stoo/c _12C _ _ _
result. In .. high tamperalU'" and 1he producl;on of cerbQn d/(J.ide. This lane, reacts with Ihe .... ry 1101 coke ~nd is reduced 10 carbon mono.ide. This, In \urn, reacls wnh th" "on ,,.id,, on 1he Ofe 10 ,,,mOve 1he O'vgen content. When the gases reach lh" 1"" 01 the fum"". they will contain about 27% catbon mono.Kle.
,h"
" I"tle hydrO{lel'l, and 'eS1 is carbon die,id" and nitrogen: i1 i•• very uRtul
,
flg. l 5 _ ot ___ ... , - . ..... "'... "' _ " _ _ _ ot_",-
,
The be .. '.om ,he hammer were CuI In lO con",ni.nl leng lh. ,nd bounOWn ., "B ••f" w,. mell ... l>ich had bHn laggo,ed twLC" Bu t"' from flggoleQ --BeST Bet"-, "B,," bars would have a tensil' ,trenglh .Iong .he grain ollh. '1811 of aboul 23 lonI/SQ.in. whilsl ·1'.eblu Best millhl r.ach 2B 1<>LV",.ln. The tt •• nlllh .crou Ih' fibrn would be abou ' 15" teSl ~ IhI: process c.nnol complete", ,Iimln." .11 IM 51.g Ind ,his fmm. , fibrous 1I.....:lu.. within the m"eri.1 u ..... ,he mlo"ody- 01 lhe me. ,I" pu.. Fernl • . Inl-..-' • Md wilh baond.oI5IlIIas '"" in Fig. 5 Wroughl Iron ..... 100 soft for u,., .. , cu"'r'LQ ,001.• nd from lhe .aLl;'" limu • Mw "..1,,1.1 . h,ving • c.rbon con •• nl midw.y belW,," w,oughl iron .nd Clot i.on.. wu m,de hom besl QU l llt .. " l/OOled ba ... Thi. w lS (;IIlleQ ST EE L. .nd Iny re f".nce '0 metal of Ihis na me previou. 10 .boul 1 B56 muSI be alllumed 10 epply to Ihi •. ,nd nollO Ih. "mi ld" ,,,e ' _ know lod.y The AP"CI"ty selec led
It"",.,
reM"""
._1Ied
,.... _ _r_ . . ........_......-
' •• • 'L!: _ __ ...... ". . ... _ .,"'" • M_ _ ' ......
fum~m.n .... ho
",ItbIJ·ul'· o. ,Iif,ldlhe INIth wnh .n iron 1Nl. IWsperdeon o;on lenl. wnh pig melting al .boul 1130 C ,nd pure i.on al .bou t 1600. C. As Ihe cerbon cOOl.n. ' ell. lhe ... O... p.tty m ...... ppeared in Ihe mell .nd lhe.. clung 10 the end of Ihe puddIe.·s .. bbl,. Wh.., Ihis "bill" was u lerge .. he eould hl:ndle M extrllClld It from IhaI fu .... c:- .nd immedialely ,.,1 il undeL lhe !UP 01 • meeh.nicel hl:m",.. (Fiu.-5,) The hl:mmerir'LQ d!OY1l out most of IM tllII In tM: INII .neS It IhaI ..me lime fo
,
.Imos,
' It. • n ......... .. " ." _ _ _ _ - .,. _
. . . : ," • • 4
d,
~ .. 13 In. wide . ,f in. Ihickl we,. hell""
In ' bOX co.u.inirlU chl:.coal for periolll o. 8 10 to de,.- " • IImp"flIU" of ,boul ,000 ·C. OU.inll ,hi. lime . h, i, on ~ c:-tbon .nd IS lhe be ... were rellr liVIIV Ih'" Ih'- absorp,ion IIghI through . Mu ... w"e fo< """"".wino • 1"'.0.. !mm lime ID time • "'US gl~ir'LQ' erudo: 'orm of Quslity conlrol. lOP 10 15 Ions 11. time could be trllledl l1M u rban con"n, could be r-ou""ty r;>oruroll"" by !hi "nolh of ,he hell, 00. if 100 . hOf! .h. ""neUllion w ould be In<:Ompl . ... Carbon con'ent could ","ve. be below . bou. O.s,,;. bUI could easily be ,.h.", 10 1.5" for le.g_1 lhe mu king 01
pent""'"
"",..:6ed
.-
Th . p roc,lS w.s c a ll.d I h. "c.m.nlllion p.oce"" and lhou"" h wu , ffective lhe IIItticulty WIS thl:l,he Cltbon conlen l v.rled ' rom bar 10 b;I. ,nd "'.., 8Iong tM: llnolh 01 • singl. b4r To owrcome Ihis. Benjamin Hunts"..n In 1744 found ...._ of mehing !hi bao,. c:-ment,lLOR. (11 ... ift be appreeialed !h.I' ID mlk •• eruc:ib" w h:ch would .IIneS up 10 'M leml)l<.'u ..... n.. 'ied was very difficult" Ih., . i",.). f unhe,. M uwd only pIg-l. on .m.lted uling ch ••COII I •• fu. l. Ih u. ,limin,,1ng Ihe impu'ili .. II)hoSphoru$ .nd IWI"h ur) erising horn cok. luel. Alter ··""menling" Ih. wroughl iron In lhot ulW.' w' Yhe mell"" brolr.en UP 114,. _ .bout 50 lb. " • time - in lpICial cley crucible .. This looir .boul 5 hou ... The contents of IhaI cruc:1bIe _ re lhen ClII lruo p,, -he .."". splil. ellt-I.on moukh ID ' mm bars. S,eel made by tl>1. PI'OC . . . w i t _ and is - kno ... n IS " Crucible S,..r or "c.sl Steel". By ",,,fully ..lecting I'" tn':11I1 CI""nl'" bell _ tnd. . . . ",11. ulir'LQ p'"e. from diff....,1 bell made In IIifferefl, MII. ~ .... '" unifoiewd. ler IU:iMlrior ' 0 lhe old 1
.h"
wellktd Iwhh some CI.e) 10 m.k. l.rgtI' m. fm very large objKU. _ " I Cruc:ibltrl casl inlO ...... (sand) mould. The l1eel COUld. 01 COUfM, be """"'''''' (in lhe I"hion Iller ID t.. described - u..f' ....... t Ih .. bool is Iboul l) but l, ...u ,, _ _ .Iy uMd .. mply as • lough. .ILOng h mly _m odd tmrl _ .... , meb , m"lfill hIgtt In Clrbon, u- ... movor mo.l of i,. and Il",lty. ecId carbon '0 produce m" ..1I1 of lhot ."""Ired _Iysi •. bul • li" I, .enaclion will allow IhI:,.a eec:h '''P Ilso IIfiL>l'd Ihe i,on. 10 som, e. "n. removing Impuri'iu. and lhe IIn81 l1.p inlfoduced ,he cl rbon in the fo.m il was n,t-ded. Ih' p,oceosl, 001 I t Illogic.1 .. il ... m •. The MUnlllfltlln c",clbl. process w" In uN until Qui" re<:enlty • • nd lhot .. mly be , lew &m, 1I phln .. still "",,"lino· BUI the "ce.1 Ileer- (or. 10 be mor. clilirule . I':lgh-c.. bon sleel) 01 lodey i. midi _,nty In .Ieelric fumac ... and lhot Cltbon a
P_.
_,...-I,
• ..-c''''''
"
SPECIAL STEELS - high alloy. stainless. ...cl .., on. ... maoe IJy mel lOng "mikr SIHI In .n elac:lric .re Iu...- .nd. 19";". adding the alloying .lernenl. 10 lhe bem. ~""Ihe firsl model engi .... rs Md bul 11.... I."ou. maleria l. ,,,,II,bI. - CUt iron. WrO\lllhl iron and ""HI" - Ioday Ih' choic;e I, bewildering. Ind ......, ca$! iron may be had in dozen. 01 g,ade•• nd
--
For _ pr_nl P"'P'1I .... howto ..... _ .nt COi ....m..t only w,lh wI>ich a .. .. nkad a. "ceobon ,001 .Iee"'... In geAlf.' • " M ,'d" 11••1 will conl.in lram 0.05% up 10 0.2" ca,bQn and "M .cIium" caobon "HI Up 10 pe,hapt 0 6'IC.. ThHe lasl c.n be lougt>enMI by heat tt•• lmenl. bu, not haode,*, ... trocie
1'-
(!eta"""'" I .... .. nalu ..··.) Above .tIout 1.71f, carbon COilt ..., lhe ....1101 wi. be • 'call iron-. A general distoncllon mar"'" be found be_n~ln" cerbon "HI whlctl <;Onl'i"' •• a ",le only carbon and . liWe m'ngan,se IS "Io~lng ,'.m.nI5. and ""Ioy" carbon 51•• " which will include nlctal. chromium. and 0' .... ' .1,m,n1$ IIuch ,s vanadium ,nd moIyI>dee effect of the carbon. EY.n in Ih' c'" of t.... " high f4Hed" ,001 . ' H'I - "1oVI 01 iron, lungs,...,. cob.Ilt .nd ca,bon _ 11 is I.... pr'Mnca of c.obon which provid.n m .... V of lhei, propen .... It is • Hkltary .. flection lha. OUr 01 rr....a engtn,,"ng d'p,nd, .ntire' y on Ih' m""I" found in .he core 01 YOU' IUd pencil I
iron-'
.'Ioys,
..-joy""'"
CHAPTER 2
Principles of the Hardening Process Hardening hlgh-clrbon steel is easy _ people have beln doing it for ti'toullndl of Just his, the metal to che,..,.· ,eej .nd qu.nch in cold wate, and 11>1<. I, 1._ hard! H.......... ' . lik, the horse (which i, , noble ....""-' bu l doll no, "w'yS do .., . ... ") IhI, cIoH nol .lways work. ,nd • little knowledge of what IiJOI1 on Inlida .he metal will both mah failure 'ea.lik,'y. I nd " SO give .."", OcIea 01 whi t 10 do when I h. occnlonal a w kwlld lob ~ ThoM who lind thal """" ...... , "do ..," .re wrprised how ...... i, _ when _ _ who ~ .tIout horses t&kH O'IIrt Th". is. they w.n IIV. noth!ng difficult Ibou t It - vou jusl ....cI tO unden;ta nd the 'nlmal. It Is th."me with Iteel. No.hing difficult unless you ,re ICIUe!ty msking the stuff. and ,h't PIt! Is dooe lor uL You m.V h..,. • alight l)IoL l. ,n wim .."". of t .... .._ word." U - J wm ,.pI"n H _ go 1Iong. bu, yoo, will ,110 find • I;', 11 IhI _ 01 the book to which vou C.n reler if ....... be.
Y"'"
.'w.ys
Ihat really. but we ere nol concerned wilh lI<>mic theory. JUII w llh h.rdenlng , t...1. This .... Is ~I Of n_ty soIit:lified Iron. ...cl It-. will .Iw.ys be nine lIomL _ . , .actt come, of • c:trbe .nd ...... ;" the cent". ,t IM 1• ....,...IIUfl . It .. c.lted . ' BodV-cen.red cub;e"' QVlIat. Such clVI"" he"'nd lhe" in lhe melt and I . new ones lorm th.y grow on thoM ""ady there. Ih' Iln l. grouPl growing larger until mer m..., nelghboo.>ring group. Wh"e !hit "-tong 000;:_ I ...... wijl be. disconllnUlty of thegrowm , SO that whirl •• is pit:l , IooIr Ihrough the mic,~ wlM _Ioo w g ..... areal wi lh line ~nes round them _ Fig.7. fThe cry't,l, thelllNfvH , .. 100 om,11 '0 be ... n
nge.....,.
'P9'II"
,h,i,
CRYSTALS AND GRAINS
• , or , .,
.
" "" 1_
"
- O f ,"" ~ .. " b
•
--
When ""Ill Iron
.toms ...., .
."rts
to solit:lify the
,~.
in • _iN g . ' IItricaI ~!lem. IS shown in Fig.B. I have anown t .... ' Iom, . . lill" bell, lor clwity _ w. know lh't they don'llooio; lik,
---_. __. _-
_ _ _ or _ _ _ _ ..
F""' A~
"
Th. mel.1 now cool ••1111 funher. ,nd wh.n _ re,ch 1392' C In odd thing h'p(HIn" Th, In remperl lure Is •• re.led lor • Ihor1 whi'-. ,Imost .. if lhere iI • IOU_ of he.1 wilhin the ..... laI, (Fig.B.! Thil is. in f""t, lhe u .., for the •• iI • change I.king place in the cryslll sttuc:lu,e which ""IU.1Iy reieflMS hilI', (M.llllu
'.11
--"'---'-"'-"-"
rlI·71 ...... "'. _ _ _ ........ _
-_
-
through ,n ordin.,y mk:roacopel. Thu. .r... the .. g.lln .... AI • rule. the "",lIer Ihe Q"in. (within reason) th, bener. ,od ~n of llIe job of hUI unt· menl la to .. refi ..... llIe mel,l 10 ,educe gr.in Iill. Pur. troll (F,nil,1 l.nd. IO form ... 1..... I.r9'lI'alns.
A --
B.'
1)92
I
I-"\b ~ - --JJ/ _____ "'_ --_ .......-"'--"' .._--_ ...._..._.... 0
"','A'~_(
_"-
,. •,•
~, ••
"---'_ " flt! .• ,.. _
...... "' _ _ '
.... _"'" , "...
--..... _
suiltble equiomenl you would _ Ih' crysttl. re""'nglng ,hem..lvlI. ""Iu.'ly dilinlBg'llil'lll .nd ,.forming in • n,w 1>I""n, It I••, 111 "cubic", bul Ihis dm. with .n .IOm In ..ch OOfl',.e, .nd one In IIIe cenl" 01 ..ch f.e•. 14 In .11 - Fig.9 . Thl. ia cllled • "FACE-<::enlfed cubic:" cry.1I1. Ag.'n. Ihue cry.lIl. for m tggreglle. which "-I .llhII grlin boun" d.ne ... ""'1 tuCh. ch8n.ge Is possible may Mtm IUrpriting. lor lhough the mel.' i. lItnge i" oh.ptr, Thiogl; would _m VIfY diff.re..., it you were _ of llIe ,toms I E""" 11 won.~ temptr .. ture the" would be _ dilllftOl betw .... you .nd lilt ""xl _ ,nd ,I Ihi. high I.mptrrltu.. you would find you had plenty 01 room, Whit .P!M.... 10 UI I1I "lOIid" I., In fl'Cl,
onoItly Impty SIlK'. _n w ilhln Ih.
CfYIlaI : It la lhe lorces which I'CI between !I'll IlomI which give us the SIInsalion 01 ~,
NOI only Iht!, The .toms Ih.mMlv.. .....,.t ,t.nd 'bit. Trut. they unnot ch,.. ..,..t .. they do in • liquid or I " ".. but IhtY do vib<.1I aboul Ihlir me.n ~Itlon, Un fKl. It 1,Ihi, vibralion which genera t.. lilt coIou,ad l;g'" we .MOCi.,e with hol _"11. In wch circumll.nc:es it is nol 10 .... rpri~ng thll some of \he "om. un d,lft .t>oul • lillle, They do Ihl. 8111h. I;ml.t high lem~"lu'n. •nd 8t this "cnllc!oj" IImptrflture Ih.y c",y oU I • complete ..,n,ngem.nt As Ihl ....111 cool. lunhet we meet Y.I -,hllr "I.. esl point" . Ih,s time 11 9 I O~C. ThII hlt.Id •• ch'fl\II back to tile orig,n,l Body...:.nlfM:! cubic shtpe of F;g,B, ThiIl '" Ih. "b'ighl "d" .nd .bout Ih. ttmpefatUfl we IhouId normally u.. for Iootring. Cooling down "iP fun"" IhI" is Iound In .mll1 poi... again. ,I 170' C ,.....,. la no chtnge 01 e
,"ht,
11<'_
1I which Ihl ,rflSl poinll occur Is very slightly 1I11t.rem whtm t.e.ling lrom Ihl! found wh.n cooling.
EFFECT OF CARBON ,.". IIcI ;1 does nee
"
,'ona."
fd-- _
/
I
0
0
.
t iSlsb
,--_ . .........-...........
'ill, 'OC"""'OI,_"~''''OI_''_''''_
,
$011 <1 _ •
w 'lI_m,d, ice-lolly I. an
~-
The urbon . ,.......... Iound .Ctu,'1y within the ferrite lthey , .. much .....,let than 11>8 ferrit. Iwmlt I. &hown In Fig. l 0. The numb41r 01 dlUOl.-.d .toml w hich can be accommod.,ed in \his way cIoel de~nd on lhe " mptUltu",n in 11'>. ClOse 01 Iny liquid .olu lionl 00 1 1\ also daperKII on ,he !ype 0 1 CryllIl. ' 00. /Thil h..... IrfI90rtInl burinu on the herden· ing PfOC...... _ sn.1I _lall,l. Funh ... .' lho\Igh they at. a.l .... ~ w,thin "'" cf'/'SI.' 111t_ \he carbon ,toml aon dritt or diffu .. jU11 I' CiOn the "0m, 01 iron. Dui 1hi' dri ll c.on oceu, " .ny HmI. not 1"'1 .1 the .".., lempe"'u",. W. "",11 ... I.,.r lhe\ the iron .nd carbon .tom. can "10 be preMnl In 1he form of • -CompOUnd"' _ ifOl1 ca~ - but rh;' .....0 not c;onUm \1$ 11 IM ITI()tnenL To ..,urn ID our
UV-'"
"
Utinlng c,rbon -'>own in Fig 10 The
_ ,hi' pI,e.'
cut !l1lQ
.001.
IRON .. CARBON MATIONS
TRAN S FOR ..
... t uS now IoIlow Ihil O.S" c.rbon ".el IS ;. cools. Dui with"",", .II,n.iofI '0
..!>al i. haOPlnlng .0 lh. carbon Ind .he Ferrite .hi. , I",.. solklllica.iofI Au • •• ni,. I1 • homogeneous IOluliofl of bOth tub$tlncel. How......,.., '1100I'I" ,he fIIeI p.oUII lhe ."..1 POinl 11 aboul 180-C arrd ooofIlurthot<, o:I'oe composrtlon oI.he AuSloni,. sIowIv wngu. un.~ " abool 735C 1I con"in. 0.8~ CI1bon Ih. mu lmum 11 eln hold II Ihl. f " , l ~ r"A.'_"F¥ ,._~.. _ ........'~,, • "'·f "-,, ___ lemperilu.... It cln only .ch.ev. Ihl. __ ,_.. eonrichm.m 01 ,,pee. lhe P..rlll. ",,;OS to be .....oun .. duto to . In lhe rela'ionshIP of .he ;nes w•• h 10mB of iron .o lorM Iron C.,bidfl TIt~ 11 FE,C . cooled lIowly N.lu.all y.• he ,mount ot Pearlit. will depend on the Clfbon contenl Iond comai .... 'bOIII 8,1" ca
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D;aQ.Bm", whkh sho .... s the efie(:ts "I bOIl> carbon an
"Sle ..r' I1he f~1I
dlov
no,
bur th er. '5 a ....lfY clear one in E!>CVclopedi. Brillnn;Ca. in Ihe seCtion ~ "Iron and Steer', This can be looked a' in mOst ~blic libra'; ... I have shown ,he 0.5% Sleel we have just consIdered B$ 8 venle,' lonll. The uppe<' I"esl po,nL or CHlieal lemperaIY", Is shown by Ihe lone ABE, and Ihe lower by OBE. You will notice Iha. 'h ..... coincide 81 'S"; we will have a look 811his In • moment bu, bafote do,ng so. lel us loOk a l & Iyp>cal ,ool-steel. wi,h a carbon conlenl 01 (say) 1.2'l(,. I have sllown a venical line here also. We Slart wilh AU$I,,"II' u befo.e. bUI 'his lime ,I co.n,ins mOr" lhan the 0.83% which is lhe ma. lmum which can be held in toIulion 81 , he low~r c.i, icDllempe •• ,u.e. (This Is ebouI 720· C in ,h .. case). As ,he _Ieel cools below Ihe uppe' crilica!. which la at aboul 900 C, lhe Austenile finds itself loo .ieh in carbon Ih'5 lim ... whereas the previous • .,mple waS .ich in ferTile. So. 8S Ihe 1empe.alu.e falls urban i. PfO\Ilessively r.. j.. Cled. bu, il is rejeculd in ,he fo.m 01 iron clNbid, (C .. m.. ntlte) fo •. unlik. Ihe Ci" 01 Cat, i.on, Ire .. carbon cannol exisl under 'h ..... condiTions. W.. find. the.efo.e. ' hat tha g.ain, 01 Aus, .. niT. Ite now being surrounded by /irSI. sl.eaks. end Ihon grains. 01 Cemenli1e: Ihe'o is no fr"", Fe.riTe availabl ... Ely IheTime ' he s'eel hn 'eached Ihe Iowa, ef ilical' .. mperDlUre hhe line BE) ,he Ausrenile has again ..." ,.. d down wilh 0.S3% d,ssolv .. d carbon. " belor.. AmI. as befor.. Ihis Iransfo,ms 10 Pearli,e .. Ih" m.. ,.1 cool~
foe.
'4
~
..... ", _ _ .. _ " , _
C_IC_"" ..' through 'h8 cn',ca!. We now find g.ains of Pu,liTe surround .. d by a.eet 01 Cemenlit8. (fig. 141 in contrasl 10 .he p.. arli'8 a<>CI FerriT. 01 Ihe lower carbon steel. Now look al .,ul with 0.S3% carbon. You will notic .. thal .he two line, ... p.esenlonll IIle upper a<>CI lower c.iTical lempe.a.u.es (th .. "a".5' poinIS") now coincide. I1 is. ahe. a 18Shioo, a " Euleclic" solution. simila' 10 thal lovnd in solders s<>CI bra.inll alloy,. So,h 'he crys,.11f8nlio
"
fig.
... ..
"-
11 ",. _ , " ' . -
"'''-'''' '', " _Of,,,, , '_
/~ T ENSILE
STRENGTH
frIIoRDNESS
!tun
0·.
0 11
." CARBON
r.,her confusing and are difficult to .eproduce. Howe".". by e xamining D Sl>8Ciman Ih.oogh lhe mjc,OSCO!>" .n expelienced melallu'gisl Can easily re<:ognise the ".a,ious constituenlS of Pearlil8. FelTile. and Cemenlile. and by noling 11>8 p"""",ions of each can mike. lai. eSlim8!e of Ihe ove",1I carbon o;onlent ol lhe specimen. To IWm up; we would expect 10 find very IIl1le Pearlil8 and a 101 of Fe .. ite in a low carbon (mildl sIeel ...... ilh Iha pr""",tion of Pearlite inctoasing as we aPl)r'Q3ch 0.83% <;;Irbo9 case. Fig IS. 8uI I must emphasise Ihstlhe ... con· sideralions all apply only 10 !Ieel which has been bOlh healed and cooled SLOWLY. so thal 11>8 li1l1e al""'l have ,ime la find Ihei' .ighl places. and Ihe cheml""l changes al lhe Iowe. ctillcalline have I;me 10 cornp4e!e. 11 is wpical of a
o
"
"hol ,oiled ba." Which hu (0' $hould have' bften no.mallsed when vou ,ecei~ it from the me.chanl Cold d!1lwing (e.g . Brighl Drawn Mild Sleel"! ..... ill nol aller lhe type of struClure IPearlile-Ferrite. or Pearhle-Cementlte) lhough il mav altel Ihe me<:hanical strength. and eSpeciallv 11>8 ductility. because lhe fo,ming p,ocess has diSIOtIoW Ihe g.aln •. The stfllClu,es found wl>8n the .,eel is cooied loo quickly for lhe changes la occu, .,e Quite differ renl. So. let u. now have 8 lOok sI Ihe effect 01 Olher lhan slow cooling.
EFFECT OF COO LI NG RATE Lel u. 8gain consider Out pie<;e of 1.2% csrbon sleel al (sav) 800' C. which tempe.a!ure has been reached eilher by slow cooling Or "0..... healing. The AUSl8nile will ha"" partly transformed. and Ihere will be Au.tenit. grains su.rounded by some Cernenlite. Wilhln lhe AU'l8nna mOSI of the crystal. will COIlI.in one or mo.e r:arbon slams - Ihe "solid solulion" COndilion. Now lel u. reduce the lemperatu.e very Quickly. Theft will be no time I", Ihe alom. 10 rurrang.e I""mselv". no lime for cryslalltensfo.mation.
.nd inslead of r.nding Ihem",,'ve' In , I.nice for ma lion ..... hich l&aves Ihem plenly 01 room Ihe cam.m 810m. are trapPed inside Ihe cryslals wilh inadequale "","ce for Il>9m. In addition. Ihe ""Sl enit' is compelled 10 relein fa. mo.e ""rbon Ihal It can normally hold at Ihe lower lemper.ture. TI>8 AuSlen"e crySt811 .'" put under eno.mous intemal Slress . • od Ihi~ is JUSt Ihe C(l(Idilion which is associated ..... i,h hardness. In addition. Ihe Cementite which Is p.esenl is unable 10 QYslallise normally. but InllBed Is constrained inlO a needle_like struclure (known 8$ an Acicu lar" formation) which i. very hard indeed. In f.et. it is Ihese "needles" which help In Ihe formation 0/ 8 good cuning edge. This new SlruClure _ highly slressed CryStal5 assodaled wilh acicular crysl,ls of Cementite - i. given Ihe name MAflTENSITE. and is Ihe basis of.1I hardened carbon SI ....1. I have already .eferred 10 tile need to ~t Ihe melal slowlV. partly la en,Ure Ihallhe v,rioos U8nslo.malions have lime 10 occu •. bUllhis i. also ne<:essary 50 Ihal .....e <;;In be SUre Ih81 Ihe mel81 is hol righ/ fhrough. It does lake lime la. the heal to ,,,,,vel through to the inte.ior. A similar C(l(Isider81ion 'Wlies w""n cooling. When cooling .apidly I"quenchlng") ..... hat about lhe met81 in Ihe middle ol lhe workpiece' The oolllide has coo~ fasl. 11 is I,ue. bUI h Is clea. Iha! (wilh la.gB Spe<:imen. &speCially) Ihe COte maV not have kepI UP .....ith Ihe tooling of Ihe e~IBrior. Wht! Is lhe effe<:1 0fI Ihe melll? We tan besl answer this question ..... ilh anOlher diig,am. Fig. 16. Th is shows temper8!u" on the ve"ical scale. and lime on Ihe hot;"onlal. Because melallurgistS ,"d engIneers nead to uamine cooling 'iIles wlIich maV IUI hours Or days IS well a. IhoM which 18ke only Ihe odd second or ... lhe lime scale it compressed _ il is. in fact "Iogarilhmic". The diagram sho ..... n <7
,elaleS 10 no panicular .t.... l. but It I. Iypical 01 most. every speclfi""lion has ils own "S-cu"'e" like IhiS. It isimpo.tanl 10 .ealise Ihal. so fa, 85 .....e .re concerned. il musI be used artlv 10 illuSlf'ale 11>8 elleclS of lime/lemjMlfaIU'" changes. Det&iI inl",prelation 0/ lhe dlag"m 11 a matte' for e~penl. looking at fig. 16 YOU will see Ih81 Ihere are IWO "5" shaped cu",es. On the left ol lhe line A8C ...... have a zone where lhe 51eel Is AUS\8nillc (in a slale 01 solid soIulion) bUI 11 is "unstlble" - 11 has nol yel ltaMformed bUI is feady 10 do so. On Ihe .ighl Of Ihe line OEF ..... e have the steel in ils final. 10tally l!1InslormO'd State. In Ihr. 'rel. if we were IRlking about the 1.2% carbon sleellhere would bft 9,.lns 01 Pu.li" lW.munded bv Cemenlile: if 11 ..... ere th" O.S% .tNI we looked 81 ea.lie. lhe.e would be gra,n. 01 Pea,lile surrounded by Ferrite. In bftlWeen Ihe IwO "S" cu",es lhe SlruCture is unde'90ing the I",n.fo.mation process and will consist of " mixlure of Cemenlile (",,!bides). Pearl,te and Ferrite and. of course. some 01 Ihe o';ginal Au"eniIG - c a,bon In solid s.oiulion. The neare. la Ihe line ABC. the mo.e Austenile. whilst close to Ihe line DEF more of the Olher constiluents. At lhe bottom ollha "S'·. IwO horizonlallines are shown ckltted. At one. markMl Ms'· Ihe hard Martenslte slarls 'alarm. and bftlow Ihe line "Mr Ihi. change i. comp4ele: lhe melal is all In lhe hard condiliOfl. Fat "silver sleel" Ms lies 81 aboul 150 ··C Howev",. Manans1te CIInnot e x;st 10 Ihe righ ! of the line 81 'F" Now. conoid" a piece of hlgh-csrbon st .... , ~I Ihe painl ·0". It Is at .bout 780 C. lilt cool. IIowly 11 wrll follow the Una OPT "king pe/haps 24 houf'i 10 cool down 10 15°C. The lina panes Ih.ough bolh 01 Ihe "S ·' ~U""". Indicating that tOlal !fanslOfmalion la Pearlile and Cementite has laken pinta. The material i.
.u,,,1
,
",nnnled" _ th' .t.~ h •• Md tim. to go thrt>ugh .11 the ch,,,,," w. t.lked .bou t ...H••• Now iooII" tM h.... OR. The .... tal hu cool.d through .n 'dentic.' t.mpe,,,tu ••• anw-. but this t, .... in no more Ihn one uco;"ld· AI no poin. _ ; 1 cross lhe "S" CU""'. 10 tht no Tr.nslorm.t..." 10 Pe.r~" Is p<'''ibIto_ But ;, HAS uO"sed both lhe M• ...cI Mf line •. indicaling th.t to"'I"n.rorm'horIIO M,n",$ile
hi' t'ken pl't" Th l. umple i. ··ha,dened··. T..... I f ' Pimples of the two .. lIow.nd rut cooling. on lhe eII.g"m • line You will _ -as . which JUST louchIs ,"" """" 1'1 ,he left_hand . S' Cu ..... This Is lhe sklwUI '.,. _ tM --c.iliclr flIl' - 01 cooling which will .chie". , lully hardened Mltt,nt"1c CGnd;"Gn. (The lociItion 01 I"" poinl '5 will depend on
".m••.
·c
[NOS
tM IVlIfI 1'1 '''el;;1 mighl Iypically be2 Or 3 MCondIJ The q""nch shown by the li .... "OU--. however. ~s crua IM " S" Curv, ABC, at 'V' and ·W·. In and oul agaIn, Betw.... 'V' .nd 'W' :some 01 lhe Aulll"l'lil. will "ansform 10 P.... ite. bul I. ,'''' cootlng CIJ .... only Ii... 10 .he right 01 the line ABC rnon>enlMiIy the will carry on down OU 10 form M'flent,t" The final ,t". w~l. the •• for•. be m.i"...,. M.n ...,it' but with a linle P",lil, .. well. It will not bt .. h,,,,. BUT. the pch lIOme 01 the ,lIoying II,mlnts 8rl .dded to modern ··c"bon·· st ... ls Is Ihe Imp,ovI' mInt 01 the ··Ih.ough h.,dlnlng ·dI ... c"ri.~I«; the .11oy modifies Ihe "5" curve. A pI.ln. un.'~d .... rbon .tlll I1
._.;..0..
··NoI. t"" "
10 1'101 1< I'i& for _ but In ............ ,_~ .. t ... del .. " .... I10W MUCI1 ....... ,. will !loO' "" .......
--''' " -------
DI STO RTION QUENCH As _"
~:>
_- _._--
'""1191'"
,..17". __ ~\ -, .. <---~ ... ....... .... c.L-_ __ . . . . . . 1000 . .·
DURING
THE
hardne'l$ _ ... hequtntly conctrnld wilh Ihl SIt'PI 01 thl wotkpiecl. especially when mlkong g,ul/I' or lorm loo1s. A li\\ll .hougf1t will thll there is likely 10 bfI, dimen.ion,' eh.nge with alllhe tfansformatiOns within Ih. m.,.' .nd Ihll, in 'ddilion. Ih, highly '''eMGd C~lal$ will "IIe"ect" JUII 11 .ny .1f..Md membe' will unde, 10.(1. Not only th" - the very act of coonng CluH•• Cor1!flClfon .nd in • "q .... neh" this COfI"Klion is suddotn in the •• ' ...... e If the wor1
"" "'
.... _
"
. ...
not tOO ~ in this r1!splCt BUI NO Ihick IfICIIon 01 steel c.n be h.n:ItI....:l righl through ........ ""'... alloys _ MIdtd For ··Sit..... St"'~, which COfIt.f"" , ~tlle Chromium 10 MIp mll"". tht Iim,t 11 5(16 inch lhick. though tht a. 01 ha
It
The higher .he cooling ra,e .he g rea.er .he risk. In cases w~ere "sh~pe" Is imponanl we musl usa 8 slower cooling ra.e. even though .his may mean .hal .he quonch line for Ihe centre of .he work may CtOSS Ihe nD$8 of .1Ie ""5"" curve momentarily. fortunalely .his I1 no. SO Important in ar1 icles not intended for me'ai-cunrng and ,n SDme caH"S can be an 8""anlag8. expecially for .0010 subjecl ID shock loading. The risl< 01 crac:lul .hey do n"*ld proper temperalure con.roI. The .imple•• method lot uS ,S.O quencl> in oilin51ead of waler. The risk 01 crack'lljj and dis.ortion is considerably reduc& 11 can also be abtein&! carbon s.eel. bUI is adequate tor tha
'''''1
I>UI)lO$8.
TEMPER) NG JuSt as.he ""Good Shepherd " lempers the wind .0 .ha shorn lamb. so the prudent .000-ma ker ,empers hi. ha n:J steel againsl shoclc Ioeds. A hj,gh-carbon .001 s."t
•
PfOptrl y heat treatee quenc:h oroduces Martensi" - hillhly stressed Au.tenile crystals in.erspers.d wi.h needle-lik' Cementite. fo, some purpo&es. however. we need high $1 ... nlllh and resilienc, 'alhe, .han hardness 85 such - .he clas .. c ca ... being .he lprinll. There i. 11<) reason at all why a spring should be HAR O; the engineer e_pec.s .hem 10 have a htuh yiek! sir .... and high resilienc •. InduSlrially il I. possible to achi ..... e .hl. direc.ly but 'his doe. need s~ial equipment. (And. In any case, commercial sprin{lS .re ... !dom made from &treighl carbon tool-51l1ell. The ,,"IV way open ~ o mOSt of us is .0 harden ,ighl 0<11 (preferably In oil) &nd then ""mper ba.:k"" ~ o the desired condi.ion. We re heDI
.". pert""". 300·C - "blue". A. '~is rampereluru the ne&dles 01 Martens"a c/l8nQ41 Into li l1 le ""nodules" end, of coutae. Ihe crys.als e.a completelv . tleu .....oeved. The SlBa l will be "hard" relaltve to mild 5.....1. 001 nowhere near as hard BS • ",l1in{l'ooI. To sum up. we can modify .he 8tNC'u'" of our hardened 51ee! 10 sui •• he purpose we llave in mind by 8 secondal'! hoa. " ... men. BI comparativelv low "",plttl'u",,,, I shall be covering .he detail needs for various Ipplica.ionl later. bul you should bear in mind .ha' '"Tempering" serves Ihree putpOH"S; to It .... relieve .he "tigh." crystals and so ,..;u.ce Ihe tisk of cr,ding; ,0 improve .he 11'..... size . loO ,h81 you can gel a keen cu.tlng &all, in • ~"'r chap",. deal wi,h Ihis In more detail. npeclally in relalion 10 lhe special nnds of I~ol'! tumer's tOOls. which musl be btough, up to a vel'! fine poliSh and sharp
....
ALLOY STEELS S.~ .n,y -odd
yea,s ago. wl>en .h, ··Slandan:J Practices" of model en{l,,,"rlng wer, beilljj established, ca'bon 11881 Wh just en IlIoy of c,rbon end .... I. True. I1 w outd con.ain a few Imourtties, for Ihe days of charcoalImelted iron w ere over (.hough Hoit:apfi,1 was •• ill u";ng Humsman crucible lool·steel made from imoorted D.nese
1tI,. _
alloying elements. The diagram Ifig_13 on P"ge /8.1 is drawn for Hplain"' carbon sleel. bill each alloy will ha"" a different characteris, ic equi librium diagram. some \OIII'! e<>mple.oc indeed . AlmOll' all carbon.oo1 S.&ell those d.ys contain about 0.35% of Manganese . lis main purp05e being to coumerlc, the effecls of Ihe Impurilv Sulphu,. Al tl>i, le\Oel,he effect on fill. I 3 and henc:e on .he heal 'reelmen' is negligible When pruent in higher amoun,s - 1% or moreIhe steel ne&inll tempera.ure i. $Iightly dillerenl. Ihal is all. These steels are eSHn.ially ""carbon" steol. wilh eddir;ves to imp,,,,,,, performance . tu .he elloy con,ent r'ses. however. and . mpre e$pr!Cially. wllen a combination of alloying elements is used. then ,he equill~lenl diagrams I" figs. 13 end 15 become very compliCated indeed. (Chromium, lor uample. lorms a very han:J carbide on ill own!. When laced with a s.ee l con.aining mo ... than about 0.6% 01 any of th.se elemBnts (and .hey can be Nickel. Chromium. Cobalt. Vanedium. TUlljjsten. Molybdenum. nIBn;um and Olherl) .he answer '0 the heat Ireatment problem '5. fo' .ho mod.1 engineer. "" OON'T"I A nice piece of 3% nickel 0.3% ca,bon 5.eel will (if you are it is EN 21) make e.cellont connec.ing rod bolts. !>U. un)e .. you have t"" euc. heal 1(.ltmanl d ale i. is best left in lhe "80 supplied" .1&1,. Even more SO 11 vou come ecro ... any of .he higher ,lloyed ste.ls -
"If,
.nd .... n _
·ev..""
110
~.in
if il has com.
the Sa.p'· H•• t I.....".,.nt of t:uch. without propel ~II .nd equip.... ne. .. likely 10 W dl"'Pl'Oln1ing if not catllUaph;c. (Ho_r. t l1l'i.11. in " later eh~PI8r. dui w llh 1h. h.lt Ueat"",nt 01 110_ 01 the medium carbon " ' HII . .. hich Cln, .... hh c .... be tr •• Quill efI,cliYelyl, Fjrqlty, (Ion'1 forgel thl1 brU'ng. •nd 10 ,n .... n e.o.tent. .. elding, iI. lann 01 .... lu.. 'men'l
from
,.d
lI.n",
SURFACE HARDENIN G There Ire m.ny situltionl. balh ,n full·si .. end model _i.-rlng. wtl... • hard· _,ringsur1ace is n.. n pins ... u,mples Th. usual IUV\IHtfon made by .. ,It... of ,r1icln in Model Enginur Ind -, ...... h... is ,0 UN SI""". St"l. hardlfl. and then "mper back. This iI nol • very ~ lOIutron 10 Ih. problem. f irsl. lhe l.mrMoring t1Iduces \he "'rdne... 01 the _ .. in; ....-fee. and. 1ICOnd, l&mpered Martens,t. is nol IhI lint m" ....1 for • 10ld·beatlnll comPOnenl. Ho,su 10' cou,..,1 A 8uII'tti Iype 37 cIoel nol make 'h' bell 01 lown CI"''IIes. ,nd vou would be h.rd pUI 10 i, 10 m.ke J.n '0" gauge
loco on an , 8-inch looI·room !.Ihe. no how eeCIH.te It .."The Insw.. I, 10 ..... mild or mediu," carbon of lpeCiflc,,1on Ippropri.,. to 1ha Ioedinll c:ondition •. ,nd Ihln 1< modify 1he .... .-faca It ye, of lhe m.tal .a Ihlt il c.n be hl'daned. You .. " remember lhal lhe earliesl me1hod I>f m.nuleel.. re 01 high Clmon lIeel invot-.", ots hlI1inO in Ih. "".... ne. of arbon. rh, took • long lim., bu t if _ arry ....1 I~ N .... proc:ass for • sheI. lime .h&n ,h. c..ban .. ill pen,,,,,. onlv • Iho" dl""'ce. for mod,l. we onlV need. Ih'" I.y ... - pertlap. . . ,m,1I IS 0.005in. woule ..,..... - and Ihi' " whal il ;odIieved t>. 'CASEHAROENING' The ••• re v•• lou waYlIn wtlich il an be done, """'" wtl" don't Involved Mlylh'ng ""'" IIIIn. bIov. I,mp and som, SPecial compound. bul ... QU'" "",clic.1 lot !h. model.ng,n ... Onc. !h, • ..... rll>C. I.V" h•• been ca. bu';,ed the Cln be healed aM Qu.rn:hed and. In motl Cite •• cIoe. no! need InV !.mPlfitlg. The ....It is I CO'. which it SlfOfIII and I .... gh .• nd , ..... rI., which is .Imosl 111.... -111.(1. F.. r1hI<. " iI n.I obIa.• nd " is POIIObl 10 h.rden S&leeh.... ty, and even 10 Cl'" OU t m.chining on one part 01, component alte •• noth" Pin has be~ tuMee. hafd.ned ! give mOf' det.ils of lhe procedure on page 64
m,,,..
"eel.
p'"
""OCI"M ve..,.
ape"",,",
CHAPTER 3
Heating and Quenching in Practice heel It ., musl be tor some I.i,l ... import.n, pUrPOM, How ....... ,he,. 11. eu"s whe .. ma!el of """e Of le.. known prov_nce un be '1ICO'CI.d, .nd if you ••• In. lighllPOt Ind cannot gel new "eel. lhen the IoIlowiog t1bl. m.v "'Ip In "'II\I'!sling!n. prob,bI • eafbon COnllnl o t old 10011 IIC. I emph8S i... Ih. word "Old". IOf Ihu. d.yl ....en lha humbl. COld chisel m,v W m,d. from a non·temlMfing nickel .llov
JM M . , ...i.L The first _ .nd imper.' .... _ T2 ' Iy it 10 llKide wtlll m.t,rI,1 .ou ... herdening, If you a .. nol tur' lDOuI tIois - if 11 it JUII I piece 01 ~ lIulf \'0\1 hltYl pk:hd up from Evan. 'he SCrip ~ 11Ie" my IKIvice Is "Oon"l"". I have by m, " I wrile Ihi' thl SAE 1051 of steel. whlcfl MIGIfT be I.... nd in • scr.p mol",.':', ~ dart. If typed oul on paper 7 inctl.. ..... !hi ti.1 would be se,a.,1 fMl long lea thin one liflh ... ""pI'in" a,bon "",s - a l( lhe ..11 ,r, or !.Q highly IIIovwd - .nd 'V'" .1 you knew Ihll you, PIe<:e ....85 c •• bon "eel it hed prob.bly b" n hell " .. ,ed .I,eedy Ind would ......... ""001< 'Melling wfor. rehar$n. In$. The cMnc;H 01 rll\ding "'w ,,"I ....,. 10 IIN, treel on • K .. ~ap these <»YI ... llim. Ftr be" e. to nln wllh • new 1IIIcoI of stock; aft .. Ill. If you ,r' going 10
" Carbon
to.
"""''11
.m
'h'
rrtOf'
,.
"et'
In this chap'lr I .hlllI ~eal with Ihe prlCtl<;.itl aspecll 01 Hea, T,eelmlr1l. but I ... IeIvin\I dellil dllCUssion 01 Ihe eelual dn'ieea I" .... , Fo< lhe pUlP''' of !Ius crntPll'. therefore. 1 sh.~ .......... d\ltt YOU' 1OU,e. of he., it. like Ihl e"", ... 01 your RoIl,. Royc •.. tdequ.,. for ;\1 IIIIIJIOM·'. I IIO'nll '0 I.ave ton· tidI'''1on 01 r.mp,ring 10 rh. c:hap1l'. 100. la Ihi' ia .eallv quill I MPOra" is_.
n""
Type of TooIzr 0.1 CfOWbI",; Picka.2tS . Screwdrivers 0.8 lI'\IfI M.sonry thistls. 0 ......,. 'O<;~-d"".; Wood·l!lfll1ing Wedgea 0,9 Cold Ch,..Is; Shea •. blad..; Black,m; lh . hol seua: 1.0 S .... lte, Cokl Ch.sels; Old wood. WO,I"II\I m.th.ne ""u... : Hanc!Nwl. 1. 1-'.2 Eng' ..... 'ecutr"'llloois , O.;lit. R.,m... .,c..
12-1.3 Files. , .3- 1.4 Ruor •. Engrlva'-s lools; S .... lil ... 1 4 up W ire·(j,awlog diet; Cold S ....... M~ny
01 In... o;ould be m~ from hlgh·lj:l"d " .... but !his tin ,asily' be diSTinguished by using the '"Sparl< T. .,--_ _ lhe Modai [n9_·. HandlHHJlr. In .ny caSl, how ....... lhe mlle,i.1 .""..,id
,
first be .nnee led (S"" pall/! 7 L) and a small lest pioce then sawn oH and t8Slhardened wilh 'he e.,imaled cerbon conlenl as a guide. Heating We have already ...... n Ihe neod for slow ..... ,ing. and I canOOI emphesise Ihi. need sufficiently. The queslion is " How ,Iowl"" If PU' in' o a cold muffle furnace end healed up with loo muffle. Ihis will .... lfree. Wi,h the aver&ge muffle. in fac', 'he work will ..... , up slowly enough il PUI intO Ihe furnace when i. i. already 8' t.... herdeni"", lemperalure. (In $Oe ordinll)' blow ·llmp Or gls torch SOme care IS needed. 11 i. all loo easy 10 overheal Ihin pans localty. I find I lake about five or si. minules to bring a small I~ - about i inch. 3 inch long - up 10 Ihe .rresl point. and i't.ke' a li11le longer to climb the ,emaining 60 e C or so. This gives good result • . and can be laken as a guide Bener 10 be 100 slow than 100 las •. Al Ihe arre.1 poim there i. a lemplation '0 lu," UP the gas. as the met.1 seem. 10 be making no progress. This Is juSt Ihe w,ong thing to dol The hllle atoms are In proces. of m(>\ling house. and W(".,., welcom. being hurried over tha jobl K.... p heating ar" s'eedy ,are and when the metal $latlS 10 colour up funher vou are Ve l)' nearly at Ihe right te mpereture Overall. I~ short answer 1. 'hI! '(DU must use your judgement. and II)' to get Ba much ellP8rience n you can. If 'fO\' rely on 10tCh Ot tilchen /ire hu ti"ll. For the odd D-bit that will be used once and Inan scrapped Ihe heating ralG may !lOt be all th .. tr;tical, bul '(DU MUST pay ~nention If Ihe 1001 Is en Importanl 0118. likely to be used for yea,s. Once "" to tempemture you must hold the ...... for SOme I,ma. Again _ "How
"
long"? You have bo,h 10 ma ke suf8 'hal the mel al is hol right to Ihe centre. AN D give .hose 8'OmS .ime III dtift '0 Ihelr new >pol. ForTunalely in this ca"" tha lmSWer is quila rlefinite; mel. llurgisls and gener. ,ions 01 blacksmi thS over a centul)' 0.mOre h.ve established Ihe rule : naal fOr ONE H OUR PER I NCH Ot THICKNESS. once lite t~ is up to tn . hardeninlltamperalure. This means that i linch thiclr. 1001 should be healed for about 20 minu.es. Yes. I knowl You ha", never held Ihe heat for as loog as Ihisl I am SO'I)'. but .hat means thst you ha" never &Chleved Ih. ma.imum poSSible hardness, elt~rI JUSI 10 persu&rle you I have sel up speCiallv and hardened lour pi""es of carbon steal f,om the ""ma bar holdir.g Iha temperalure for one. fiva. ' e~ and fifteen minu.es. lhe la,,' berng "'ighl for the t-inch stock used. The hardness maesuted on my " vin'8g0 " Shore Scleroscope came OUI at 74. 7B. 78, 8 n~ B1. 'especIJVely. Th<>se who know th e" Itardne" numbers will rellise ,h.. thest figure. are all low ~ but equalty . thB'\' "'. 'e,lise 'hat th. "Shor.·· i. 001 ""itable lor such small speCimens. A subse-quent ' eSl on lhe las • .speciment showed 8 hardness 01 above 900 Vk:hrs. 'nd this i. abau' righL The reduction In hardn8$$ 10< ,M &horler heanng limes Is quite evident tha "one minUle piece" i. softer "a< hardened" Ihan lhe .~ should be wh~" tempered. It is quit. tNe Ihat our lools a" relativelv small compared wrth tho ~ formarly used in industl)' - 0, today. for Ihal man... Thev don', con"in mu"~ mGlal ~ but thei, surface are. i. Imall. tOO and Ihe RATE of heB! 1Ian,mil8;o" needed 10 gel .....an a t-inc~ 1001 to full lempe,ature al ,he cen". In 15 minules " vel)' high. Clearly 10, the odd OCribe'-poi o' it isn·t all thel Importanl. but for cUllinll 'ooIs i, does man.r. I shall. I"ar. be lemnll
fCIU about the u$8 01 • mohen salt-ba lh for healing. and one of Ihe gre8' edvan.$ , of ,hi. type of fumace i. Iha' 'he .,...1"11 TIme can be reduced; Ihe ... Ia of bill' t ..... fe' i$ much belle<. Selling the ~ In a ookI muffle furnace and lening It ,.., up w ith th' lumace is good praCli"". Il10. Ior the muffle heating "18 il abou l doe same as that 10, the metal. You <;.IIn ....... the haating lime in ,hi. way. Right Temper.ture . At first sighl It llliglll be aS$Umed Ihat we need 10 lake ttt. metal up to .bove the uppe' critical tempeflllUre ~ the 11118 ABC of Fig 13. ttut thi$ is not tne c ..... Firsl (for high ... t>on I~ .... teels. lh" is) we do need _ "Free Caman';la" when we quench. and this does nol eppeer unlil Ihe melal hIIS f~lIen below Ihe upper critical c.mpef81ure. SOCOnd. a.perience shows Ih.tlhe grsin si •• is more favo-u'able 11 the mOllS ! I. Quenched f,om a lower ...,pe... ture. As • general rule stee ls IIavlng 1% carbon con"nl Or mof8 are Qll8nched from below Ihe upper crilical .00 lhose below 0.9% I,om above il. Thi$ ill. ··gene...r· Nle - there may be SpeCial re"no f.... de p.rting from it ~ and one o:on sequence is Ihel .he quench Ienlperalure does nol VBI)' much ova, the whole range 01 carbon Conten •. NOla Iha. ... haa! treating OTHER than lor pure har· .... ing Ihis mav nol awly - see Ch.VII . The fOllowing t~a is drawn up Irom a ""mbe r of " authorities" for $l8e15 all 01 which conlained about 0.35% manganese - whll today i. regarded as • ""might" ' carbon Ileel. The eJ
n-
Th8$f! lemperalu,es a,e for quenching in water Or bri".. For oif-quenching the melal is besl healed perhaps \0 ·20 ~ C highe,. bul I do not ,dvlse going above 800 e C, FILE STEEl. usually 1.25'16 carbon with 0.5" chromium. glv.. maximum herdness from sooe. but It mUSI nOI be heated much .bove Ihi5 figure. In all cases il is muc!t bene< 10 0l:na1n Ihe COfrOCI quenching temperature Irom Ihe manufaclu'e'" Of lhe .,ockists if the beSI 'esul,. Ire 10 be obllined. You will 'lOt go la, wrong wilh tha figures given in tha lible. bul SS is always Ihe else "Perfec'ion dftmands more care" . If the EN No .. Or the newer numbe ... from SS 970/ 1972 ! which . Incidentally . inCOrpOrate Ihe carbon conlun, in ,he spe<:1Ilcation numberl Is known. then reference '0 .he 8ri.i$h Slael Co'po,ation may produce Ihe 'equrred information. ll00k in Ihe telephone directol)'. Or II)' BSC. Smnden House, Rotherh&m S60 3AR ). 1/ the SAE number (Society of Automotive Enginee.. of Americal is known. Ihen del. i5 gl~en In Iheir handbook.. which shouk! be avel lable in the local refe,ence lib",l)'. This gives almost ALL sl.eis made to U.S. r.pedfica· lions. and they lIon't differ much from BS 970 ; manv h.~a 'he sama number. In Iha case of 'he oil-hardening g.uga sleels The p8 boys I T.... oldlimar. could eSlim8le almoll 10 a degree
"
Ju"
by looking at the .,.... 1. bu, 'h .... w ...
herdenlng ..-rt>on I'''' aU dly long. 11 vou ....... a g'l Of ell<;tric; fumace which i. ~tted w.,h I pyromtIl.' VOU I" In no d,ffic .. lty - prQ'lidld VOU dMd< ,he ~ •.." 01 ,he Ins,,,,men' now and &g'in. U' I1 hU no P'l'tome,,, I g.ioA 101111 hln'. on making one on P89" 107.1 W"h g81 0.- 11" "..,Ing hive 10 "lyon 'he cokI .. , o. metal. Now. make no mi."h; Ihi. I, In EXACT m....... o. ,emptt'"u" _ In l,cl. one 10'1'11 01 P'I'
,1Nl,
w. ,h.
'h.
1'111"".
700'C 750°C 800C 825 C
850 'C '0(>0 l000 'C
Dull Red Blood Red
0.....,'"
Brigh' Chany Fled
'"
Brigi'll Fled
Y.I_... ed
The bell thif'lgto do 15 10 find lOI11eon, who 11. . . m.. to. fu,nace wilh P'I"O .... , ... or '''Ing' I elub visil '0 ,he loe.1 Tedoniell Coiloge •• nd hive 'um.." broughl .. p 10 the v"iou. II,"""rI'U"I'" the, VOU ..-n _ whll il ,,,11y Ioob lik•.
,h.
(Have. piKlmba<). There is no subltitu,. '0.- Ih,s type 01 'operien<;e. How .... '. '0 help VOU I h.... liken 101111 coIou, p1>otog«:al lent beSI 10 .eplOduc. lhen on pagtt 33 As a lu"her guide. I IInd that ,he I.'ger boiling ring (one 01 'he ,pI'll 'vptt) on ou, Cred. 90R .leculc cooka •• eached and ,~Iised ., 78O"C efte< runf'llng full on .'" 15 ml~ wllh no pan _ It : .nd Ih, li.ebed 01 • Coo.1ie< Type 8R ' . . . d s,ove burning ··Phufnae", " (the Itgg ..... ped things) lay b e _ 'OOOandl,OO 'C ,fie< 'boul 15 m""'tet d,.w;ng "P Ihe /i ... 'he r,.ebed being obou, 7 i"ch",
don·'
",,,.
The...... 'ew o'her guides. Thu lowe, crllie.llempe,.'u.. ;' In ·<.rrul pOif'l\"' "
which the colour will ...m to hang back This is .., Indielllo1l 'hit VDU . " wilh,n abou, SO"'C 01 'hoe _ifed Un passing. IIfO'IiOtd you ' " lbov. "'" "'UI poiol VOU will get ....... haKlenong ,Heel. but ...,.,. I1 VOU ... be_ Id V,,,, nea. '0 ,hil I"Ht pain' - WIfY lIigh"~ below - lie. lhe ··Curie Point"' " whoch lhe 5'",,' ee.... '0 be m&gnetie, You can keep checking whh • magn., or. as I ge< It is '00 low. and 1I sI>o
'empeflrl"".
wo'"
.,.. Mine ... made by .he ·· M,"'all ~ ·_ ... ~nf)""_bul available hom a.ve< Choemic:ais ud. Richmond. 5 ......... Of from T,P HIiIdIInd & Co. lid. FI.... Kiln Lane. "1Z~ng. B.rks. for .... in m .. toe lumaeas withOut pvrom"ar, Ii'll w.lI · known .'BeIII" Cones'" twang'" Ltd. ElfU,il. SlOke on Trend e,n be uled. Thtose eull over I 1 'he 'op whin Ihe righl .mpe.llu,. is re&ehed, .nd .ra uled In pDtIlfY kliM, whe .. ea"f..1 tamperllure CIQtIlroIl, equally impO.... nL They h.ve the I ~.. n t . tha' I....... e... be .. sed only . . DnQI. so !hI! VOU need lhem by !he I r. • A "1'1" 01 propottlo1l mull be main. l ll-..:i In an ,hil. n in .11 01 hea, _ ,menl . 11 VOU make 'hoe odd 10.-1'11 '001 Of puneh onee O. ,wice • Y"'. 'hen th. eIII" on page 36 Ihowing ,he healing coIou.. wlil meel .11 'fOu. need,. And. '0.IIn lmpo .. ant lobs. p,ovlded 'he . 'opa1l'U.. 1181 be,_ n the criti<:al IIOing ILa. for Si ...... r 5t.... be .....·.." 730"C Ind 83O -C) vou w~1 gat SOME ~ efiacL lhough no, VIf't' good I! .......em... I!VOU harden ,0011 l.irIy he...... ty lhen you w!ll ve", I0OI1 develop . . coIou, sense which will ,n,ble 1'1:1" to __ by eve; If'I any C'H. VOU hmve to !udal ,he colou. under ~r wo"'&IIop OCIndilions. no •• haM ol.n IndulUial heal _,menl shop. 8u,. It you m.ke .11 VOU. _ tool. Ind ~uges .• nd a .. herOef'lino,j "-1010"", pens .. Will . ...... VOU ....... Id ... weIllldvlsed '0 look 0111 'or , ueond· hand muffle-fumace (0.- even I new one!) or look e, ....... 01 lhe olher ...,ngamants 1.....11 in I le.er chapter. '-1in9. This It 01 1111;' ;mpan,nee in a Itthe 1001. as IT mUI' be ground in Iny CIte, but 11 it is I ' orm·,ooI. wh>eh has 3 IWoIIIe which CIIlfJO' be lormed on ,he lJI~ iding wheel. 1, ean be I n.. ltarw:e. It no, • dilr.. ulty. 11 uling a m .. ffle !he se.llng
.-.w" '"
5
,
'spK"
'wo
eRn be .educed by ""ing' lew p·,e .. 01 /fry ehe.CM1 It the mouth 01 !he m ..!fII. just ag.inst !he door. This any o.ygen Irt !he m .. tIIe - or " - , 0111 .nd 'edliCl Ihl! ..... d.bIe to 0IId0.. !he mlt,L lOon' . un coke 0. eO.II. Alllmlllvety .he..... .".". """,I--ecale p.inl." ,vlllabl., These Bra uled bv ce.amic en.mlllle ... bu, .re eQually ,ilK· ,Ive In proteeting " ....1. It It painted on work Ind is .IN<:,ive up 10 ,round BOO' C. I ..... it very .... eensful.,. but .Iso uN I IlUbltitUII, ThI. is Dron "eel) aIongsode and prQYtded VOU ........ lhet both the worI
w." _ ....
.h,
QUEN CH(NG The.. ." ,hIM quenching mediuml '" common u.. ; pl.ln WI"r. briol .• nd 0'1. Wlter 11 ctlea.p .nd easy to ob",n.•nd will w",e .lmoat .lIlh, mod.lang)n"'-, need .. 8r1ne gives. s.omawhal bell" d.nlng a Hact end ..-n !live 1'110" ,vln cooting _!he "lUllS a .......... unito ..... 011 ;1 .... n' ••1 wlMn quenching comol •• WPH - lhe sllghl !oH 01 ... rd ...... is
h.,_
"
accepted as a lair e.change to< the redu<:ed risi< 01 distortion aod cracking. Tha ac,ual cooling proceu wi,h the three quenchams il dillerem - i. is 1'101 juSt a case of dmare""" in d~gree DI quenctl . Wilh plain waler Ihft inilial effect is Iha \lenera,ion 01 s,eam all DVer the _rkpiece. This cau",. an inlense arid sudden cooling effecl. as ,helale"t hUI 01 vaporisa'iDn D' waler is very high. However. Ihis resullS in Iha _rkpiece being blankeled in a sleam jacket a'lll steam Is I vary poor conductor 01 heet, The cooling rata would drop drama ,lcally if Ihis Insulat,ng coating were nOI remDVad. So. the work must be &giI81~d In the bath; if Ihis Is t;kIne, then cooling proceeds a\ a 1."lv rapid aod steady r81. until Ihft approach 10 lOO· C.IAs we shall 18ter. onee ,he 'emper.tu" has lallen '0 al>oowev",.. Ihe r:ot:>Ilng rate (wi,h lhe same degrea of agit8lion) ;1 ""IV linle diffe,enl from Ihal of wate,. Balow 400· C. however, Ihe oil cools tha work vary mucl't llower. Using" ,est rig. It was fouod (wilh slill, unagltalad
"*'
Huids) Ihel water would take aboul 3., secOodl 10 riKIuce ,he lampemIU,. 01 a standard probe fmm BOO ~ C 10 420 ~ C , and oil al>o
' 00'
72 5~ "'di<~
of _ I t__or",. u.,;.g . J _ . .... . _ _ ..
-.,,-',-~.
Q"""'II'_
~
""'.
'50·
"
I'h"''''' •""*,,,,,.fo
... ""P'Wi,-" ,_
~h~'
_ 1_. 1itIW,K
",~.
""' . ... ' j "
....
._ b' . _ -_," . '_~'
225"
i iI
I
11 245"
I
I
255"
I1 ,
I! I
,i I 295"
305'
I
h n
juS! fl081 in it, bUI you can euily me ke up
e simple test lIydromele, il you want 10 be
. ",.
A plastic tube Is weighled 50 IlIal il
fIolIlS wilh the lop about t incll aoo..e IlIe surf"". In pla in w atet, h is IlIen calibrated bY sening it in brine of dil/etlng strengtll$. If you slatt with tile Quencll balh 81 8%, and let it down when it tOps 10% you will tie within the not very Impatlantlimit$. Deca,bu . iu t ion , Occasionally one find. • tool Ihal ha, been p'O\lerly Ireated , .... erythlng a. it should be, bu l somehow it doe' nol seem to be lIard, A lile can "touCh" it. HOW1lver , any ."emplto saw It In tWO .esults in a s.aW ~8de with no tee th on It I The cause is su rlace decarbu.isat>On _ the ou le, skin 01 the metal ha. "'st some of its carbon content. and it is not herdenable s teel any mO(e. This is the origin of the okl blaCksmith" rule "'Iorge la'ge and grind small". The tool was always lorg&d oversize . so Ihal any decarburised surface wauk! have to be ground off. The problem ill nol 'cul8 lot rhe model engineer, as he ill not heating lools Will> _nks up 10 • r:oupl. 01 Inches lI<1uare. bUI It can happen. It is caused by lhe aCl>on 01 oxygen on the motal, and tllie is one ,eason 10' .... oiding IIIe use 01 O, y-gBS lleating flames, It ciln also be caused by scale: yOu will recall Imm Ch.l. Ihet Wrought Iron w as made by the reaClion "I i,,,n " . ide with the carbon in Ihe clSt i'''n. ~ r8mlldy 15 . "I c"u.se, I" 8,,<>id scaling in Ih. firsl plac •. U lugge5ted above. I have very little lrouble wilh lools a'''und ~ , 6 1(1 :VS Incll $Qua ,e, but the few half_inch nne. were all made delib.ralely abGut 1132 Inch """size al IIIe pr:Iinl I" pe,mit SUfficienl grinding dnwn. Ovlt
youi Lr>cal ove rheating i. almGSI inevi table if " ' y-acetylene i~ used, and I ""Inlo Ihis in m(lre delail lale •. This tVPfl can be i.reparable, with ". lde inclusions "'.minog in the lI,ain bounda.ies. rendering tile steel usele ss I"r anything but as a m;ssile, ~ common"! difficully. though, ~ w"h Wrm tha lape' and IIIe paint by grinding altar he8t I.ealment. Fo. mhe. cases - e.g .. wlle.e there is 8 5m ell prot",soan (In a Is'ge, mass - Ihe remedy ;5 I" fll a "'heat sink". A p,ece '" !!Crap "HI with a IIole In I1 (not 100 la ' ye a IJlece: ",,",ething in p'DfJ Ihe mein mass "f me,aIlIS!le1 Ov,r the delicate part, and the wllole llea ted up as one. The slende, part is protected lrom Ihe di,act heat (lI the lIame. and w ill .each Ihe P'(lpe. tempe'8ture JUS! the same , bolh by conduction lrom \h. main body and by .adiation j'"m tile shield. The p.olecting shield must, "f cou'se be .emoved bel(l.e queflChmg. N(I prOOI .. m arises, " f course. with lu.nace haating. Metal which i, (lvemealed will alm<>s1 C8'lainly c.ack on the Que nclI. The beSt procedu,. Is t(l .rOll w(l,k, anneal Ihe piece. and st8rt again. It ~",wev8', the sleel h8$ baen broughl up bedly (lve. lempe'SIY'O . yellowy-red. 10. example then I1 will need rel"rging before it will be eny use 8l/ain. If il h8. IIil Ihis mav Include s"m e s ludge , wlllch mlghl Interfe,. witll the Quencll_ In industry alewate m81hoos are used 10 keep lh. balhs clean, bUI I"r us, simpl" methr>ds a •• Suitable_ For water, JUS! pr>u, It away
.nd ..... Irnll, Bri... m.y be kltPl longer U" pI •• ,1C conI ......... no! m".1) ..-d l!>en fl ... shId - . . Itl' "nk wilh pl,nrv 01 w.t,r. It Ihould IISI , long lime '''\''WIIY Oil I. more predo......-.cI eOllly, bul • .impl, '''einer ca" be used to r,mOve the dirt. KHP. lid on the oil-beth when not In ...... I Il.-.cl Ihat even .fl" Iwo yeatS my own oil-~th ..Idom I'IHdI cle'nlng. 1.-.cI I .... 0;1 n'IOnI Ih." mosl model er9neers. The ",ope< oil should be uled it " ,11 POMibIe There VIlioul IJI"ades. .nd .ltCh oil eomp./lny .... It, own. I use fI.P Que.-.clila An". though Ihe'O ... el'd,l. 19" i. "mOSI as good .nd eheeper, h 1$ u"'onun.,, Ih" the .. oil' ,r, no longer supplied In lhe old one gallon lins. bY! • 25 I;". (about 5 gallonl drum can be sh"td bitw.... triendl - .nd • 400 litre drum could be che.p.. l1ill lor club purell..., failing 11 1PtC1" 011, • good ~Spindle Oil" of .boul SAEIO 10 20 vlt.eoslrv will serve. flul NOT mOIOr oil, whic:h ~ blended fOf quile dillerenl servic. and chlr,eteri.,ic.. and mOSI """"'I~.ny NOT "used' II'KIlor oil This .. downrlllhl dlngoe«lUl: il can corm,;n up 10 25')(, of the tlNvi .. IrltCtions 01 peuol end can Il.sh 011 ;"to. furlOU' fire if used lor quenching hol m.lIl. The .1.. 01 Ih. Quench balh muSl lICCOtd wilh the si" I.nd qU'nlily) of the work p....sing thr<> of hot metal 11 0 ~t~gllo • ....,;d und ... t'mpe'.,Ur' .... A h.II_inc;h ,001 5 Inc"" long w.;g/tl about O.J5Ib. for lhe odd I;In", punch and ,imila, small cuu,' iolIIl kelP "~arge "GOIcIon SY'up" lin. " 'h'" hev. good lids. bu , fo, serioul wo,k • plastic "builde,', bu<;k,," doe, vI1'\' w.U. lThey can be hid wilh 1Utl. Thi, will hold up 10 two g.al1ont end It varv lObuli - it will ....... wilh'tlnd lhe occuional rtc:e:idwt1t with hot met., on I"" ",,,,lcl I have.
.re
"
Ia'",r tin for oir. wtrich """" held ..... ul';"" paint lhit hH • lid, bul I em sorry ' 0 find Ihll pr_n, <»Y paint 1101 hili' very poo.t<>\M. Mi... hold •• bout f ~11on, which ;. quir.ldeQua,e for ,11.he work I do. The iniri.1 rem~ralu" Ihe mr , h should not Dft too cord T'ue . V<> some Pea,I, ,, f",m"ion. Quenching TltChnlque . Thi' doU requi,. lIOme .ttent;on. far 100 many peo~e Ht Ih' WOfk in wller and swirl ;t abour .AoIen11v· The recommendllion i _ _ books ,l>lt the wire, ;n lhe bud .. , be ... r In rollry II'KIlron II me .... 1h8, ste .... will lorm more ",ach", on rhlt sid. end it will be under q ... nclltd. The.. iI plenlV 01 m<>1ion t< di""'cI Slelm 11 lhe front. end perfllPS
/
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" lhe side', bur very little al Ihe back. Oistonion illn.v,,,bja; il"ldeeod. s killed fil,herd.ne.. UII Ihis phenomenon to ..... ighten • filt which hn ben, in the hUtingl Th, pr.f'ffed method IS • "'IIIvtIv SLOW ci.eula, motion of .....,n.. combrned wllh an '!
r'"
the middle p.n of Ihe quench 0, the vapOur bI.nk" in rhe caSl ot oil. With 11 very 1..11' o~jeet yOU mlY hive 10 move it more. butl1dl genu." to.void hot oooI.nl. but cItr"ly a larve p',,, n&eds • large< " .... ncl> 11..... end yOU should nor try ro get away with .n inadequ31e volume 01 coolant. In Indu.,ry. of COUrN. el~borlle lV5.em, 01 p'<>\Mlle".. underwater jels. 1.-.cI so on •• r. uSl made by lhe rhouasnd 5till ha.-.cl quenched in b,i ... , There Is JUII One po1nl lbour rh. oil queneh which mav be helplul. I find Ihet • deepis/! ~rh I, bene, thin one 01 1"" " .... voIu .... bur "faner' n... me.ns thatt'" t'f1'IoI ~ which nlads an oil QUench can be moved ..-e in • ven;cal di.ltChon thin 0'~1 .., In m ......
t""I,
10, .X""......."
r'"
- a,.
"
elSeS I lind 'h" no rol ..... mo,ion i. nfI
a'
Sleg. Qu.nching n,. c,i, ~.1 !)In 01 , .... Quer.ch is 10 g.1 'he work reduced In 'emperalure !)ISI 'hi k..... ohh. "S" cu .... (Fig 15, JUII ID remind youl) Or.c. past Ihis pOinl Ihe cooling Cln be Qui" , 11<1 1IIow.... - Mln.nsill wiU 11;)1 lorm This being SO thef. would - ' " ID be no "HOt! wIIv wl .nould nol .. mcv. I.... work lrom lhe belh oncrilll. IIIhiS
"4i!'
Tt",.
P.ni,1 QUlnching I. no nHd ID quench Ihe whole of • la'Ue wo,kp,ecl (nor nMd tP heal the whole of It lp, Ihl1 mallll') if only part nellds h"d eninu Alte. Nllorging Ih. end 01 mv pichxI, lor e~ample In .CI which w,1I hi ••
.noullld 11. 11 Itwo forgi"lllempefalure ;. aboul 9SO·C _ I haa. up ID be.ween " Blood" Ind "Che.ry" ,ed and quench ju., Ih. end 6 in<:h'" Itwo painl .. Ihen briskl~ rubbed wuh, brolPOnl i, clean ' hold 1110 ,he light uOlil lhe colours ,un up 10 IIm"". lhe poinl. ThuI ,he poinl is hem lrod ' emperlld. bul lhe main bo
fi,,,
CHAPTER 4
Tempering
"".1
"mpe,
The nlld 10' IImplting hIS beln discuHld In CI'I.II, ,nd 10 some ..lInl ,he !Mgr" 01 lemper 11110. BUI wIIil., .'" CIUIfI'Ch "n'l9If.'Url is f'irly ....'" mJoed. depending m.in'" on lhe Glrbon OOnll nl 01 Ihl ,t . .L tI.. \lmplring lemoerllure depend. llmesl enl".ty on tII. UAI ID which the 1001 will boo pUI It is nol - . . suffiC""t 10 fly" "Lal .... TooII·' flW the lem"", needed (say) for IU'n"ong EN 1" will be very diff.renl lrom 'hll Ipproprlall 10 • 1001 10 an chmld el.I ir1)n. no. effsct. .. wl h,ve ,Iready "en, i, to ImpfOye Ihe .. 'oughn ..... reslllIne. 10 ,hock - " lhe upen,. of IDmI of Ihl h"dne ... A tOOl rrol sublecl ID shoe:'-. .uch .. I flfl . mev rrol be tem"",,,., ., all. whil • • IIlflng will be lempered almost to tIof,. It follow. thlt conside" ble pflt$Onl) Judgemlnt must boo uMd. if onlV to tlk, acoount 01 ,he work _mllly done In Ii'll shop. 0 ... reason for uoing elrbon IIHI looll In'''1Id 01 HSS (Ill'" I
-
ha ""e"", booen m",lionId. ilul t ,how I
lougtvoess " • ,elalivety low lemper ), mUll be 1IId. 100. TtI., the loss of y be more Ipp."lnll"'n ...1, Ind i, dllfocutl ID pul I numbe< 10. tMud. lhe PQinl 01 I lI1hl 'ool mly well show • v'rillioro of lWO points oro the Rock_It IClle ""'" lhe ourface. (Hlrdneu I8Iling number"nd Iheir delerminllion Ire o;pn. 1ide<..:Iln Ch.B) There 1, I funhe, poinl •• nd one .. hieh I bel"". is oh.n O'IerimenL The ~mle, model engi ...... ing d"b. 1I ,h.,. ItI. ,hi ··Society 01 Modll .nd EIlP«f-
lu""" diegf.m in Fig 19 I mUll .. ,""'"'" IMoI lhe ttclull m.". 01 lhe will 'I ..... from 1lee1 10 . t .... wiTtl . I •• m I . Il1O""'\1' pi
m."I"£ngi .......~1 Tlmpl<.tu,... Hiving uId.1I thet I w~1 'ry .0 give IDmI help in .he form of \Ilfldelina in lhe tIbIe below. I hi.... run
de",
The chlngl In toughnetl .nd hlfdnels
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published . American Ilrms wD.lled tMI. ~Ir... 'Ith.,. Mrd8<,h,n did In the uobIe I have Ified to ;,on oul these $ff.. but whe<" in doubt I IMv.
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Into QII'" • difficulty 0111< Ih l•. H diffe .... nt
.uthoritl.... diffe,ant It"'ma~e,.. and different uN" Quote ~.rying tempe" fo, the pme tooll. In PIInlcull<, Am",lcan "",e..ce book' ,,"m to give 'igu," 10
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..,.rn .. ' .. tools.
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to 15°C higher thin do Eu",pean ones.
Thl. m.y
~
specification. but I I
TEMPERIN G TEMPERATURES FOR VARIOUS TOOLS
-.,- ......- ... .--
200'C
...... Cu
I '10 .......... ,» , .......... lto-21O 1(J..
c
or
~c:.. , .. ""'"
C, . . . '~ 0100 '$
"'~ouI
NOTES ltl •• Soo
0 . (0._' OriI/Vory_ ~,-
OriII~'
,~
1 ...._
no-zoo
H...... _
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2U.. l2S
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14_'_--
",. . Go .....
="'..~ \1'1_ ...' "" ...... _
11. _ _ ...............
_od"' ...9'.... _
-,. _. '" ,. ,'" ,-200' C
"1:' ' ..
25.!1·27ti' C
U0-100
'
2»200
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nO·2$O
2»2$0
=m
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So .... i....
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5I-i
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Si • •
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The.. tempe..',,_ .... tt..:!i11Ortll11y, " . x:I"..:I Wllh "T&mpering eoIoufl",.nd
"""w"
_ publications $imolV ,,,I .. , to or "blu," ;!\Slud 01 quoting ,he actual I!9Uf' In ·C. The 100IOwl"{l Cln b$ uHd .. • gu,,", but again, !he., .... slight clllllflncn helW(tf!n cliffa,,"! publl ... • lIon •. Th ••• i, .,SO I problem In IfIle!'P"',1ion: wh.t son of .,.8w lor ... mpl,'
...
lempeft wa have been Itdvised to UN In thl p ..t ... fBr loo high. When the KCIII'ed ptlClice ..... e,"b1ilhed cerbot\ "HI ,00II we .... un~11y uNd, bolh by ~ anglnee" and In moUllry Toot MCtions _ .... '''08 - • 3'" inCh Bril.nni. was daslgMd !of hlll·inch tooIa - .nd .... uMd in
Ii",
.n
,
2' S·C
lJgh\ Purpl. 275'C
, ... Str.w
22S·C
D,rk Putpl,
28S·C
Su,w
235·C
Dark Blue
295·C
D,rk SIf.W
2 45-C
81 ..,
JOS · C
P'-81 ...
315°C
G,ev
Abov. about 330·C
_ _
Reddish de'" SI'lw 255°C
8'ow'.... e(!
---
265·C
The.. cojours "e &$ vi"w"o in davllght or Strong tungsten lamp electric light. fheo,o will be Quite at fault il judQitd under • ftuorllCent tube. We shall look at tile u .. 01 colour-tempering in more deteil I.ter In .". chapt.. , _ _ 1., CIO .. of I.th. 10011. First. let u. tNnlt ag.in abou, wh.a, wa ..... doing. The WlJ II:I 01 tempering is '0 incr.... 'M IOughnea - ,eobll..ce to shcxt .nd chipping - _ lhouQh lhis me.n. • -'lght toM 01 ",,,:then. Clearly In • -.rr.-punch 'M risk 01 damage "om bIo... is conoiderabloo. BUI in IM cue 01 ll1M 10011. WHEN EMPLOYE O ON THE SOAT Of WORK ~ONE BY MODEL EN GINEEAS, I would Ougg ... ' Ih" Ihe
M
Now. Ih, cuning adge I, ",bjlCI to h .. nng. We can use a highe, cum"g
lpead with '"High Speed St"l"- ,Imply ~nu .. I,. tempe'ing lemper.ture lies belw"n 600 and 700°C: som. lI,ad.. wlll lIill cut when ,""·hol. WI UN low .. WII
tightly - juSt suffiCient to eflect a linle grain refi""ment and 10 give some '!rep reliel 10 lhe crys,,1 $ltuClura; Ihere is still some marked increase in lough"" .... I firsl temper the whole rooJ 81 DeIW""n 1 BO·C and 200·C. and Ihen ··Ie. down" Ihe shank o"IV 81 around 280·C whll.t keeping Ihe 1001 point cool eilher In a bath of water Or by uoing lhe ancient device of sticking the business end Into 8 new-dug potalo. This gives excellem "'8UItS. both wilh "Silve, Sleel" and wilh a straighl 1.15% carbon &Ieel. I use en even mOre refined me.hod for my Ivory·turning lools and Iho5e 10< slid .........1 work when "o,n,mentally lurning" in exotic wOOd. end Ihis is dealt wilh on page 74. Temptl,ing Procltdu, •. To be prDll"riy affective Ihe tempering p'ocess muSI De given lime to _rk and we are also faCed. as in the ClSe 01 heating be lore Quenching. wilh the need 10 De sure .hat the loo! I, hol righ. th,ough. If we have 8 tempereod surface with 8 b
CO
Tempering should tllke place u .oon as is preclicable ene' Quenching. The 1001 should, of course. have cooled .o nOt more I han SO·C . and cooling to .oom !emper8!ur. is $lifer. The reason fo' thiS expeditious tempering i5 Ih81 lhe melal is unOe' in.ernal stres. from the quench and if, n is mOSI usual Ih' workpiece has a "sh_" a. 0PI><>5ed 10 belng IU'1 D block there is risk of spontaneous cracking arising Irom di ffe.enllal conUe<:lion D. well. The'e i. also a risk of "crazing" ~ lime cracks: Ih"'" can appee. if ' 1001 is lenloo long in Ihe "'Quenched condilion. This ""ed lot "has"" i5 one reason why horologisls and gunsm11hs like Ihe " blazing olf' p.ocedure - Ihe lempe.;ng I.kes place as soon a5 Ihe work cornes DuI from the quenching oil. I1 !o< any ,eaS<>n tempe.lng must be delayed lhen It may help if Ihe work is se. in boiling waler fo. 8 '1ua"e. 01 .n hou. Or SO before ""\ling il .slde 10 aw,it Ihe final Ire81menl. Heeting for Tempering. Firsl, the "easie. way" mentioned abo>re. Go end look .! .he cook •• in Ihe kilchen. You will .ee th.1 il has a Ihermoslal on Ihe oven if gas Or electric fired. or 11 built_in Ihermomeler in II if fi.ed by solid fue!. Vou will , I think, find .hat the .hermo"al {108$ up nurly 10 300·C - clVtlinly 10 250·C ~ Or 10 "Gas Mark g ". (Degme$ Cenligrade _ 140 _ t 1 times lhe gas ma.k aPllrDJr,mlllelyJ So. you have 8 good Ihe.mo.taliCIIlly con· trolled. ot al lust ··.emperlllu" indlca.ing" tempering furnace on .ha premi...,.1 The cookery book will give yo
Irish stew 2h 'Tempering Oil." which CIn De used 10 8,aised pigeon. 4 Sm: Ctrsse.oles. lemperatyres 81 high BB i. normally 2th: le5l81"9" of .oasl duck alc. 3h, needed. IQuenchlng oil i. nol witable). However. you do need a substantlaf conRoast chicken 20m/lb: lasl $Iaga .oasl beef. ISrnI1b. !liner Ihin one may O\Ie,hnl t'" oil Cottage pie, 1 th:Mincepies, 25m locally - and if using gas healing. ' genlle Cheese Slrsws. ISm. bma. not t hl son you would u .. Ior Yorkshire pudding. 25m: mOSI pts., brazing, 25m: First stage of ""St duc~ or The Sa" 8aln i. Ihe normlll me.hod 01 turkev,2Q.-3Om. Ilmpe,inl! used In indultry. Tempering Scones. tOm; B.e&d. 30-40m. $lilts ere Quile innocuous, bfting a monu" Flflil slage of .0Bsl Deet 01 Sodium Nilrile and Pot8s.sium Nitralo. or pork. 20m , (Nitrile. and Nitr.,e! which melts al l60·C. Again, you need a subll.anlial conlainer . and t use .he oule. v8s.sel ' ,om In addition. you probably have a deep ~ an old-fashioned glue-pot, Fig 20 shows frying chip-pan, Chips a.e cooked I1 Ihe selUp; Ihe old boiling nng I picked up lto·C !Of 5 minules or so. and then a. a sale for a few pence finally gave up. Oliowned" &1 t9S· C. bUI the oil enn Ind you ..... the pot here on 8 replace· llfeiy bft laken up 10 abou, 2OQ.-210 · C ment. Ordinary mercury the,momelers. an an el""tric cooker. (One has 10 be usually nitrOgen tilled, are available which ClNfu! on gss. as unless the oil i. f.esh go up 1o 400·C. and Ire nol e.pensive IhIIre will soining and some vapoutl , lhey can De had from labo.a tory &Gulp11 you compa.e Ihe above wilh the menl $YPIlliers, 0. o.dered Ih.ough your ..... on j)y the liml oon"""'ion il 1$ WOtTh nOling thaI' 1001 Ihls book Is publi.hed Ihe usual model which ought 10 bfI .empered a, 200· C is englnee'" suppliers will mar1(e. Ihem ;n alten beller trealed if il I. "cooked" for ils .a.he . s maller quantitoes . 100rect $Ypply "" time al 190· C lhan if merely "heared t,om Vaughans may involve • "Club • the colours run up" . The Irying oil , purchase"). There .r• . 01 course. a numbflr tlpecially, is u",,',,1. u Ihe heal Transle . is 0' brands. bulthe only SO" I hl"l uHd I. -..lIent. The only caveal I would enle. is Ihe DEGUSSA type TSt50!ASt40. h IhIrI 11 would De p.udenllo use an oven or COmll. es a powder m the consislency of ~an Ihe.mome,er , as the !hermoslal domestic ... n, bol must bfI kept dry, as il ort domeslic COOkers CIIn gel Oul m can absorb moisture lairfy quickly. It is CIIIIbr,don in lime, non_loole, and lhe only .... ious haza.d is Y"" CIIn, of course, use "'rying oir' IS a th.I, like some weedkillers, If absorbed IIInpering oil In I~e wotkst>op, and you inlO woodwork io. vour overalll! it ...... slill be able 10 oblain Ihe wecial
m
a
,.e
...._"" ... -. ........... -. .,." . ."._ .. ""'. "-'-' ..,,,. ..,'.-----_....... ,..20 .. _ " I
---- ~
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ri ... IlI"ln - lhe,e i. nol. IS a rul .. '". nMd 10 incr ...... tha he'ling rlla. la.., the work in loo th .. pr .. scribel Iwi ' eh I,om lime I, Ilm ... but If It I " VS Wllhin • lew deg'"' ,1>1, will be suffid..m piece can I .lIowed 10 ,;'-<:001 .Ila . ,"" hom .. hi 1,1, IheOtlroneod 10 lhe ,ize oIlhe wOfk . ¥' IIfIfHf abou, la.b of Sill loo on .. Ib of lilt< b\>1 it i",', critical. You mUll. of eO'UJe .emember Ih., th .. lide will ,I ... when !' work \10ft In; don' l fill lhe pO' ' 00 1< Fintlly. a dell~ po;nt on heating Wt>. cold . • eru" will lorm on the lop of ,''' selt- Inill" healing m ... st ha and II ot Idvisabla 10 applV just. litlle heal 11) lilt outside" the lOP oIlhe pOlIO gel. litll melt around the crust. It lid Ihould a/w.,"J be in place when reSlarllng. Silt pol
n...
IUPport. combustion" I deal wilh "S.fety·· in hilt trealment on PlIge 102. 1ft(! 0<'IIy mention Ihis now to rllssure you tltat we fre not ,.,king lbo\It mlleri&l which is pOl_ • . The g ... at ldYantage of thiS me.hod (Iik, tha' using the OVfInl is thlt voo haye c:ompl .. t.. control of the ,_pe.alu •• 10 I, no Ilfoblem WIthin I degr" or.o. WIth "time" - you can le ..... the worIr; in" long Is you Irke . And the K tu.1 lIme can be. bit 51\o<1.r... t'" h..., ".n~fe , i, very good Indeed Th .. one thing yr>u do have 10 Wllch is Ihll ther. i. no oil or w .... in lilll, holes . .. Ihi' would be d.l'IgIfous. procedule is li..,IO bring Ihe bath UP to ,he wor!cing temperaTUI'. The worlund will se"", Imme.se , he m .. laI slowly: you w~1 nolice rh .. the lampe'"u .. ,.,1 •. bul will sIowlV
n.....
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n...
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C " .. T..... peri"". This is lhe ...... Ihod __ model
eng;.-...... accustomed '0.
CJIIorIoI.I5IY. """" 11 you hava I Silt fu.nace 11 ~ 1",'1 wOrlh filing il up if III Ihat ;Oil ~, " I"!"" is I "h •• dened SCrewdriver _ I...... I f.. ma"", jobs In lhe ."orhho p for w hich 'Ollhlll!cl1 .. d 'I"''''''' Ire nol ~h whi ... 01 COUrH, if ,... he" .. no 1I11-bath , and Ihe 1,1 ... of dDfMll lc Oven Ind chip pan I" danied ...... , ..... you mult uH "Iempe. colou •• ' D ItoodiUII the lempe."u.,. I1 caNlO' in _ _ y be disQained IS "1>eod lI.actlc ..·· , \1101 me.hod MS been U$ad lor unturies. lot ~I and plk.-huds in Ihl days bIfora th... we •• any 111n.lools. The colours I,a IOfmld by • film of QIIiM which is very lhin ind"d...cl which .... Ihlck•• IS ,ha temper.tu.e inc.uses. II:would ..... m Ih"lh .. coIou. ch.ng. is, in ,.-t, due 10 ,he lighl "lIec,ed /rom lhe ~ ol lhe m.IIIItHII PlI ..... ng ltuough .....lfI\I I~ of th .. oolda. Cerairily tha a . act coIor.l, does ~nd on bDd'I IhI I';'l)e 01 mll" Ind IhI surface IIniIh. The differenca ha,we .. n lh .. colouI fA ~mlld" .,eal .nd hl\lh-catbon .,. ., is -.11. but 11 Ih.... .. Is 'hi d'ffer.nce Mlwe,,, Ihll 01 qu .. nched and 1MQu.nd>ed carbon 11 ..... Th .... ffec, is 10 gIw • v,ri"ion In tempelatu.a 10. lhe ..... e $h8
aver.
~
befoN I It cIoII help 10 Ita.... piecl of cold -""'gl-de loo COtnPllrison If lhe PlIlel1 .'raw is !he IIm As lOOn n ,he coIou. I, ""ght" ' ,he IIlec .. musl ha "uenched _ In 011 or WII .. , to pnI.etlt Iny hi" STored In Ihe .... nk of the ,001 from taking il tun""'. The ~ _ _ no IlUrpOM IJO I., .. ,'''' act ....1 tempe.ing is ~med. The worl< can be helled In. bJowlamp. u"fIg • V~"Y 10ft fl.m ... bul when.", POI.bIa I USl • Spi,it lamp It hi QUlle ldequll .. kif ",.,.1 ,,,.,. of 1001. and 'hough il lal<. . . .,he, longer Ih.~ • gas bu.n .. , thi5 i, ail 10 Ihe good. We I." nol in • hurry I It prOYidel' very clean fI ,ma. and _ which does nol Inlerf.,.. wilh coIow /ofmalion. I:",n 10, It is nece ... ry 10 'eMOVe lhe WOfk f.om 1"- fI'm.. 10 00.."" the eo:>lo... . . .. it will not develop properly in Ih, P'.Mnc& 01 burnltlg luel. lno:a.d. it is posa.bIe ac'u.lIv 10 .a""",.. lhe coIou. with I 'edueing II'JII of Nllufllly, you mull keep the worlt I'I'IOYing .bo\IC In , h.. fllme In order 10 g. , even healing if you.re IImpe,ing 'h, whol ... Obiects whIch .... of ;".gul. . .hape can be difficult. The hell should be 'PI)IIad 10 the he....., PlIrl of lhe lIC'ion. Ind you mull keep a very c.,etul lYe on 'hing• . Fine corn... mey '"I.ke oH"' into ,he blue befo.. Ihe main body hn ,..ched Slr,w. For lud'I work I .lw'VI u$l the Utlt balh
"'ry
.'ee!
n.ma.
"
and to expo'" the wo,kpie<:e 10 the . adiam haal. tumiog il about Ih, while. The higher tempering tempe,atu,es mav need Ihe plale 10 be red-hol. You can do e slmila, thiog wilh a fi,eb,ick oven; jusl an80ge a few fi.ebricks 10 fo,m an Open box. ha~1 Ihem wilh a tOfch. and .hen hold Ihe work inside wilh IOflg5 - 8galn . lumin.g i. aboul all Ihe lime. Manv u ... a ufld-ba tn. A lray of dry sand I, healed from balow and lhe wotlc eilhe.laid up on It Or !>uried, the und balng 'umed asio:!e.o in""",,1 Ihe colou,. from lime IQ lime. HI helps 10 have a thin pie<:e of simila, me1erial laid On Ihe surface of the bed in Ihat ca ... , 10 eclas an indicatorl, The sand muSl, of course, ba kepI well s tined whilSt hUtin.g, '0 make .u"' Ihal it is a. an even ,empe.eture. I would no, recommend sand lor tempe,alures in Ihe "Pale Straw" region. !>ut fo' deepe' colours il wo,ks well : 81 lOOn as you see a ~Ie colour you kl'lOW thellhe othe.. are nol fir behind. Transmission T8m"".ing This is Ihe - cla»ieel"' way 10< 181h e lools. bUI ;1 Can be extended The 1001 is heated al thn shank end. and as Ihis lurns blue. SO Iha pUIPle _ dark straw - straw - ~In "raw colours run lowa,ds Ihe point. As soon as Ihe i>lrle Slraw reaches Ihe 'egion of Ihe cunin.g edge Ihe tool is quenched , poinl down. in wale. The vlnul of Ihis method is, as I have a!ready suggesled , Ihel Ihe heat lravels down insjde Ihe melal . and we can be lalMV sure Ih81 .he ,empering Ims ,e&<:hed Ihe centre. The difficully is
..
th.t lha temper is uneven, from POint t>aciul nOI ,ouching) the die 10 prevenl 1101 air turrenls from hea "ng .he centre par!. The tube !Jansmi•• I~' heal 10 Ihe die from Ihe Oula' perime'" and Ihe whole is quenched when I~e CUl1in.g edge. ,each Ihe tight 'empe'.'ur. Again, Ihe healing musl be gentle. The
fill. ZI "011-_ ....... _. _ _ _ _
........ -.. ...
_".-oi.-----"'--
,..U TI, ......... ""' _ _ ....... _ ..._
..... ,"".......
~n •• ge her. is Ihal tha oulside of tha . . (whkh &<:15 more or lass 8S' spring in
..,...;cel is ho"er Ihan Ihe tunin.g edge 8l'Id SO more deeplv .empe.ed - as it be. I doubt If many people make Ihei. own jIIItIlng saws these daV5, buI similar ob/e<:" can be ,empered bv grippln.g ~een two washe," on a Dolt, held by a nu\. The hes. is applied by he.tlog Ihe bolt, M.ny olher e. amples will come 10 Mind, The objoct i. Iha same in all cases: Irat, 10 heat from Ihe pan of Ihe tool which need nol ba h.'d, tow/lrd$ the cutting edge , and sewnd, to arrange flings so thal where possible Ihe h8at _ I s .hrough 'he Inlerior 01 the too!, lWChing Ihe CU1l'ng edge f,om wilhin . lNPioll Off. This is ePfl/icable m"inlv to - " wtttch has been oil quenched. A. _ as it Is ",moved f.om Ihe quenching Mitt Ihe tool 0< component is held over a _ll h me until Ihe residual oil ignites Ind !>u.ns eway. The heal so released !the - " is "'ken from Iha I""'h or lamp IameJ tempe's Ihe wo, • . For large, pieces "the books" sugGeSt binding some iron wire rou nd, 10 hold more 011 TIm "'Iheory' is Ihal lhe temper lemperature • ellSOcla'ed wilh Ihe Hash POinl 01 Ihe 011. This is non ... nse. The IlashPO;nl is --..Iy en indication ollhe lemperalure al which lunder very anjf,cial condilionsl oil wIII"fIn to ignite. The e<:tual temperature _had will depend on the mU5 of tho ~pie<:e end Ihe amounl of oil relaineCul ~ wll( have experimented a great deal 1Itd, rTIO!It Important, will "'know Iheir oil'", "-truclions In old books were lhe rnult
""""Id
""',need
\, 01 da<:ad ... if nol cenluries of !fial wilh one oil - from Ihe sperm whale - bul wilh 'he v.rillV a".lIable and used loday I would not care to give .nv inSt'uction el all "'CftPt 10 "'Experimenl fi"I'". I. woul n.....ds • little "i"lend e xperimanl to judge Iha .rnlS accurately: Ihe lempertllureS wlll then be within Ihe "Ioleranc,,'" 10. Iha 1\1l8 01 work wa do. The aClu,1 deg."e 01 lempe,ing needed should be conside.ed, bee,ing in mind Ihe. m051 of Ihe re<:ommendarlons rn Handbooks etC ere 10. Industrial condiTion•. nol loose of Ihe mo
"
final poinl: In some cases we do wanl a surfBce 10 boo of muimum Ma,dness and al tMa uma tim8 to nave a fine grain w ...lng and ",bbing pans "a cases. It this Is so. tMen il Is worth trying a temper
at IOO·C - iust boil the part in water lOt h,'I-en-hour or so. This w ill not .educe Ihe hudn .. " at all. bul will achieve some lI'a'n ralinement. For ··fine grain·· cunlng lools I 50.1l1li""' , p.ocedure on pall" 74
CHAPTER 5
Heating Equipment TlwI Open fir ... There may boo a law model engin&ers who OWn' blacksmilh·, hearth. .od pemaps more who hava inMe.ited thMn from en ea.li". generalion: il seems to hllve been an essenllal pieca 01 equip.......1 in the earlier times. I do hava a small one with a hand-drh/ton fan and I"""gh !t ~ used mainly for smi lhy work .• od Ihen only .allly. I have hardento
""""t
!i.abed. but where you can saa 11 and obse",e the colou •. I1 musl be lumtogs lor Mi. firsl SlUm engine in
"
. --"----'. --_.._' •• 23 A,
,....
hi' ~1'Of1(I'I flt.pla",,! The ordlnlry open g"ll will gl! hol """"gh 001.,. Ior .... all wonc , bUI a...., closed SI"". wuh I ptopfl' air oonltnl can boo uMd for ,nYllllng lluIl will P'u Ihrouoh IIIfI ItOOI fintblrL lf lg 231 Aa wilh the forge 001<1 or " PhutnICIlI" CIll III "sed, I h .... IIId no .. pe,1tnce using In!lvlcill. The mull fitsl be dlt
YfI'"
g""
fi.,
""I •.
g"".
"
."'_"',
a'
•
p.oblem I lind il 110 . unlike IlIe h... tlh you h.... n, posilive 10 adju l!' menlS I i, flow and va' h .....0 Inlicipl" ct>angas in .he " " of bulning. N'turally, \'OU musl I'~' 'ccounl yOUr ... ,roundltlQ. 11 IS \'OUt hearth<"" lIt.r Ill ! BUI IhI m'", otr,'I<""," I have' the use 01 lhe o;Iomestic lIOW> 10< h ..den· Ing is thll lha fronl blr. prevenl 110 UM 01 a pi"". of pipe. How""",". w,.h 110 . cw"ed .lOVe there I. litde problem 'Soa king"' : ooel Ihl fire hIS r.ached it. 'Imperllu" It I,nd, 10 put' I" QUill long ~ for Ih' sile of ""0" norm.11y cIonI, It i. u..""1o< anne . 1"9. IS the p·n. can III .1Io,,'ed 10 coc willl llIe fir. OYImlliJhl E""" il lhe r", nol "OUt' In lhe morning Ihi.;'; nollmpt>' lint I1 will h .... cooled IlIrough the critic.1 tinge ... '" "owly and cln be M' the ..hpen to lini"" 011 Some books ""liI\Illt l l>&tthe,e mlV D< a lendlncy lo"""d, bolh scaling 1 ,-.1 dlcatbu,i'ltlon wllen uling Ihe smilt, hearth. bul ,10,. need nol cau"" us 1<" much c:onc.m, I1 no trul Ihl1' hlatlh "",'"
'It
"span..,
g'"....
",,1tV
YfI'"
.... 13... ... _
'. ___ · ,~
... .. .. ... _ S/,....... 1>9<00
• Pr , . " .
Itn blnl can dt-cltburi ... bUI ""I ,r, not dI.llng ""ilh lhe Sll 8 of wo.-k ..... mallv dontr by the old bl,eklmllh You mav need 10 like u,. if Ih. hllllng lime i, h," an hour or more. bul it ~ ooly • Clse of .. oidOng direcl impi"",,,,,nl of !ha IIInl. Some KaI. will be formed, 01 course. bul 'alt ... Ieu wi.h lhe deled .1..... IfIlIn VDU INght imtgine. The alrnosphatl lIIIil1r;" the IIrIObed 11 mainly carbon mono.iCe of scal. no ;mpOfl.nl lhe wor1< Ihould be prolecled FOf .... emighl InnealIng • good W"l i, 10 il in fi"",ley !NOT fir"""",,"I) "'nlo< pICked wilh r.ne with . fillll chltco.l m .. od ""ith it. ' !owllmp, .nd 10fch. .. MOll model -..ginee.. will have SOme form 01 PI •• ffin 00 ,,"lo.ch 10< use whin brazing and it is ",*,u,,1 Ihat the.. should be .h. fitsl "' AI when hlaling 10< lletdtnong I will
_.se
'""':' ,
I.rongly you NEVER. .xcept In IIIe mOSI dlr. n",,"I11"/. uM O...,.-Acetyl.ne lor O...,.-Inythlng .IMI lor Iny lorm 01 "-rdenlng ape.lllon unll" lhe use 0I1Uch equipment no pen of yOUt dliIv ~ E..... lhen 11 is risky first. lithe gell 100 dose 10 lha ~ ......, 10< • lI~vnd. IMI poinl will be ..... _.Iod decatburlNd •• nd .Imos. Cln,intv !tom o.oide ptnetrlllon It IhI gr'in bound.rill. Second. 11 11 VD", difficult to gel evln hnUng IS 110, M81 SOUrCe i, SO COt\cenlrtlod. Ilthl flame i. adjusted le avoid Klllng 110..-. I. lhen risl< 01 UCIU Clrbu,"'I"," ""hlCh would ,esul l In er.ding 011 quenchIng fln.'Iy. It le I YI<"f' ..pen_ ..... ""Ihod of "-.ling. F_ peoj1II ........ 10 ~""""1h11 though n.. hot IndNd lhe K!.uII hilI ""/pU1 It '''timely low. In IICI. lhe 1.'1111' noullln 1"- OUtfil I uMd 10 u"" (10< "".ldlng 1 inch "eel pi".t g .... ou. fllh..- lau he" ,lIln did my .... '".S1 p.raffin blowI.mp. It le I call 0I11or... tor coutsas; 10. ill purl)OM OO"I'-lCIlyltne lorch 00" ill WOf1t VI..,. well IMUd. bul Ihlt WOf1t il nol hi" If."""nl 01 "HI unl.... VDU own a
ft,,,,,
""If"
"ame_ v.....
"
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''."........... ....
.,",
_.too ___ . . .. __ .... _ .... J. r_ _ oI .....
•
~·:7
_
-~-
I
...
.. .
...
PO
~-oI-~. . o$. ,,"'0<1
'·Sho
nog to .. 9.... the urne .pplled
to
,umar~s
Can t>o
the paraffin blowlamp flamr.
The di fference In Ihe luella nol imPOrlI "! - the "'";ng yet ... pe. pour>d mass 01 fu~ 11lquid o. gill I1 very ne.rly the Jame .• n~ , he p ••• lll" 'ke'OI.ne in USA) v~,-.d belofe burnlng, $(I ,1'1" In. n,me ia In ,11 _,0.1 •• ~. 11."",_ Suo flame. wtIl appe •• I. shown in Fig. 24 w l,h • cent.. ' ~ surrounded by. 1nOf' Of lul dilfuH outer curtain, though • K IU-' Ih_ win doopend on the ,"", use
.or ....
the In.... cone ..Id the heal .,lea' c.u... dKompalillOR of the ,est 01 \h 1....1 QII. Tllue fuel const it uents burn I
the OUI.,
.nve~pe_
using any exces. I"
Ple..nt w'thln the Ilame and ." draw n in
•
from outl>de .. well The ;noar cone I.m~rllurl will .. lOOm UCfled t tOO ' C bul JU5I tM,oond It.. lip 01 Ihe inner con. lhe l1IIu" wrll be rn excess of 1600 "( (The theofel,cIJ muimum is highet n bul Is nol r.ached beeluse no burne< 'l l*1ecl .-Id In Iny ~II$. lhen! is coosidp IbIe rldi.1I0n of heI. from the If.rM h"lI). 8.~ond Ihl. point Ihe II,,,, ~ IImperll .... d,min,"''' egain. 15 ....... e in It.. "",lid\. It i. nol ,t w ,~. Ippreci"e
a.. _....... • .. 7 •. "" " ''''...'" _"_,, _ ......,n IC_F-"' .... ZI
",CROSS the flame. bur Ihi' is the case. 11 ther. I. , lonO inner cone it ma~ be th'I ht'Iino w ill be mono efficient it Ihe IIlml Is I,id Ilonfl'~ !he worlr .ethe, thJn be doreclld . 1I'lOhlll 11 n.. gtnfI••1 lorm of the ~amtl Will be the "me for all l..ell!. I)f!tnaPl some in <><>Iou, ,nd some f..... wrll ""'" • "sh.tpe<" cone l!>an Othen. bul Ih.rl i. conside1lble diffe"n~. In CHARACTER of lI.m. berwHn .hoIe ..hicti come Irom • "self·bIown'· 00 ...... -..ch ,. lhoIe norm.lt~ used on Pr~ 0< BUll".. .nd lhose which h ...... Mpt<" .. ~ COl'1l1olled .ir supply dll1ived from • fin or blower, There i. tome "'lOnebl~ wide control of the ,iu 01 Ihe bm. with Ih, sell-blown I~pe. but any che"ll" In char'cte, leg. f,om "bushV" 1o "~I'''I 'lIQuires " change in burner heed. With Ihl .i.-gas IOfCh there i. compIet . conlrol 01 the name, bolh I . 10 tile (wilhin '.Ioonl .nd ch"eell' S
dItI_.
u...
qu."
do need ca,eful all"n.ion bol" 10 gl' p._u,. end 10 burner head J.election, And th.y do need clea, ,,;r round Ih. bu,,,., head excepl 10< Ihe speci,l on" ...nich hive e . tension tubes beyond .hI .ir en"""'menl holes. Whe n uHd In • 11'ltM'id "c."," the lI"me mull h"'" _ 10 ...... top or.rlside the entrlnat 0< 11 w~1 "blow IIMIf or.rf The !>a•• lfin (k.rose".) bIowt'fI'III is " the< more fle.an one which. lhough _.JIy "pawefful" tin 1•• _ 01 hut rlle...1is long end nlld.. ~k. With lhe li"gH type lhis .eq";,.. only lhe menipulttlon 01 ,hi conuots bul wiTh lhe lIIf-blown IOfCh lhe burne< heed mu.. be ..Ie<:Ied ec<:oodingly. detcribed I. ,·btoId blowlamp" lie usu.11y the mcHtl
n.o.e
.pprOpri.I •.
ApplVlng Ih. lI.me. Hell ""n.f.. from
"
----_... ...---
----". ,
... ~I be .... l1ed more .... enty. And. finllly. ,\ we have _ . , pitcH ID h.,(len ' .... n_ Cln ....... corl·~e .. bIa amount 01 illS The "uve" ill ,pity fu,n..::e. The intelligenl uSl 01 firebrick wiD bot' ""'''' 01" and .""''' mor ......... "".tino use \h,. . type .. First. ordinary fi"b,iCII, f,om I to 3 Inc..... In thidness. These are ,ehaetory ,,,he, ,h.n hu, ins"lato,. Ihev ... 111 ... llh.,.nd verv high t.mp.,.,,,.... Seeond . lighlweigh t "lnlWl.tinog B,k»" , 01 ... hieh "Fossaki l and " Fol ... in" ... tvpic.1. These i0oi< ~ nd feel lik, con. Ind .re inteoGed lor .... at inwlltton behind will, of Ii'ebrick in fuMIC ... They ean IHo 11 lOOO·C., 01'>1 .nd .nd deed cold I1 , .... 01 ...... _ and . " ..... bablt In I............. ail" IS firebtid. 80lh IIfIbndt Ind insulat ..... bricks can be hid ffom most builder. men:h"n,$. The third tyf* .... " HOt Fac." bric:I
lot of tNulng m ........ 11 h.&ve one of I.... old '1JliII·· Il •• · fi
Flo.
21" _ ... _. ___ " . .... _
.... 2... _
T...... _ _ _ ..... " .... _ _ ... ...., ... " ...
.'i""
ft ....... to WOttpiecI ill ve.., POOr i"deec1
On IUI . • ~ of "HI .boul the sil' of • 5116 Inch IQ 1.1.... 1001. I.id flal on Ilrebtid. 1001< r.... mlnulU ID brinog Up ID 'h' h.,deninog tempe"IUfI _ somell>inog lik, 1500 unllS 01 heat hom lhe burne, utnsf."inog onty 10 h•• , units 10 the "e.1. NOI a ~Iry good .,orI18y",lIng ~p • simple "e.v," like Ih.t in Fill. 27 the hutlng lime w . . ,.dueed to 105 MCOnd.; IOouI 500 h •• t unit .. Not good. but bener thin t..ior., You Will. of QOUTSe. quoll mv own ... ord. al'Od "'Y I"-t !he five m,nut" 01 t.... firsl .... mpla is I.t ...... loo fut fo< t.........1.Jng-uO ti ......, ~I'Od VDU would IHo quit. noghl, 8Ul .... have 10 HOLD I.... ttm",",IU" for ,boul .not.... of ... hou, .I'Od jf ,hill ilto be done on I.... 0j)etI fI,ebflek the bu"", muSt be kepI 11 full wonl. 1hI ...t>oIo: 1.Jme. Using 1hI - e ...... 11 can IHo Ihronled down, Moreover, .. lhe ~ will be heated la,geIy by radl.,lon from hot Ii'ebtick it
qu",.'
"
... , , "
.. br,"ong he'"h. heal t""menl Ihoo. end melhnog !umICe. They " " 51ill ..... 11_ tbIe. modjfied fo, use on North ~, 01" , !!'om AtCOll Lld (uecling "" William AIIdIy • Co Ltd. SIOUrporl on Sevem, OVI3 SAPI bul .. I.... ' eostly_ I'm ,h.id. ButlOf tfle .. PfKtition.', who ~ed5 tor ,11 .he P~'llOSl5 mentioned they are. I belltrle. I"" best small II'lnefll PUfPQII h"tlng "nit .v.ilabl •. The onlv cIr.wblck i. I"" lack 01 lemperatufl lndIc.hon. but il VDU us.e hea' wffieient 10 jullity t .... COSI of I Utile 'f"OU ... ill be Pfl1tv • lfMt111 r;oIou" tn'yWIV· Thet, .,e two fumICII on , .... of whictI mly be mll1lel whicll , """"'h looking 11. The I1I1fI .. Slmo/Icity k">dlld - lhe Ak:ost ~ Expon ·· Pon.bIt Forge. F'og 2S Intended for " .. by 111o .... te f...... IbroecI. il an filCh up to 11 5O°C Ind i, very in ""ating up . Onct up '0 tlmpe,"ure the supply can be I"'UC'" - Ihl lull hut output i5 Iqulvllenl to .bout 1 6kw. The,. i. no pv,omell'! Ind tempe •• tu,. must be Judged by c:okJ
h." ,bov._
,Iou.
"",11
'now
,,,pid
'. nT.. _
__
. __ •
....
,r ....-
_""I"".
..... H OI'I-fi,ed kiln Is used by ma .... ted by lhe FI,mel,S! Co . •• lheir kUn \VPILHIOOO Thill is 10 rud1 8SO " C In 10 minutes Of lID. and"";lI n.on up to l000" C. It i, filled with. Plo",n".. and ""nullity conuolled firing file, the
,,,,id
m ..,mum being equ;".len'lo 3tkw. TN d>fomblr ;. .bout 7 in • 5 in x 7:i in .nd il can be fi,ed on N.Su 9i's. P'OIHine, or BUllne Fig. 30 The,. I .. olhers. of eou .... In vlrying olllOllhll1it8!ion ,nd si.e. Anvo~ ... ho P..Clls.s Ihs I" 01 en.mellinll lor IIDm. tvI)eI 01 pa"'ry. IOf th., matte,) will hi'" I\>Ch • lurn,c. whic:h cln u .... ltv be
dog,,,,,.
_, ,,,. T"
_ ••• "" .. ..." . " ........ ' r'l .. _ _ _
I
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IC_ _
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"
:MI '''''lM
,.
_ ..... ,10<>""" .. __ ..", ",_._ >""''' ,
_ _ _ .. _ _ _ IC..,
At;U ,.-_·, _ _
_"'_.0, ,
, ,,,,,,,e~
'J'
.. _ _ .,, .
is n _ . They do lakl • I, .. lime 10 he .. up. bUI once It Ih" ope.aHng ,""'petlIU '" UM .... rv liWe POwe. indeed. All e .. lined willl O\'o<.rbl,1 song som. lime .go. DuI ev", new OM' ,re nol p.ohibil.velv upensivI - about the ...... eOll . . . g •• Ilred one. Mine hIS e chamber 5 in ~. , in • 6in deep .nd I1 "110:1" l000'C .....Imum. ,hough mosl todav go up to H_ ~ lng"
I~an
in""'llng" Ilmesl BYI He Ch.lX. Tu b40 Fu ..... c. M051 01 mv own wa,k 11 done Ill"" In In old ,I.cltic muffle 0< • ...1'1 bath. but 1 do make hlMluenl UA of I rigged up ~ ..r"ed l uboo fu,,,-, shown in Ppg. 31 The tube il"" il • pi,,, 01 '-I inch UhlU11 pipe, relic of !h, dlyl w!>en 1
u5ed "p.ope." 11 • • ·'vlntlg.··) mOlo0< ~'ivial er.ough ~o Itull to of .ngi.... ring _ i, I, nol )UII , caH 01 dirK' helti
1200·C Unlike Ihe ga.·fire-(! type. il is rel.t0<1'1'1,1 PtltCl7utionl when "'eling wilh IItthal mains ...oh~ .. Ready·-.oo mutfIn ......,il,bI, I.om wch fI,ml as G,llenklmps. G.iffin , George. and oth .... I.borllorv equipm,n, suppller$ lthev Ire P"IS lor Ihllt
w."
I\lndl.d •• n\ll' ,,' mullln! .nd !!>eM need no more than encasing In In&ul.l'11 acM~1 01 11>11 elemen, .... ppli" .... early In 11>11 ptojecl. Fig. 33 show. I hom.-m.d. lu.nace which I, supplied in
'hi'
--.
f ig lI A _ _ _ . _
"
"
hki f ' form by K.n th,1 EI,,,,,oh. . t. Inver.lmond. Penh PH 1 3EE. """"'" .. shown it does need IIU.nb filli"ll ov.r Ihl • lltCtrlUI conne<:l""'. S,lt I have .lrllKIy ",te rred to Ihe 1II1t_~th for tempeIor1de to gMo the ,.qulred tt-mal chlrKtefisl1c:t. The type whit:l't I u.. 10'11""' C;S660IWS7201 m,ln " 6 70·C Ind "an be uMd up to about I OOO'C: Tt ;5 obtlln,bll Irom Ihl ..m. IOU'C"" the temperl"ll ..lts. Ip, 4 S). The ..It i. mllted In • wekMd IIHI -pot", In indu'try the .. m.., be IIfIIe and helled by 1185 or llectricity - uiRJally the
e,tht.
Iorme, _ but lor the model eno""""" t.... wntCtI . *lrical tube !u,nae. he,ung • pot made lrom 'lee/tube I. tI" most con· wnlen t. C; .. heating "'.... nl. CI"lin probl.m. 10lh e' Ih.n Ihose ahndy mentionedland an .~ct rlc h .. tl1 is eula, to control , The siz. of ,.... pOl depend. on 'he wor1< \'OU want ' 0 do of course. bul tl\lt shown In fig J 4 .. qutle .cIeQulle The Ictuel pOt is aboul J in. ;"terNI diamlt" .nd I. 10 in deep. with th" sail bath ilH if abou , 7}- In. d,.p. (You mult • IIOW 10< th' "Iide to rise" when lhe wo'" Is PIlI inl) It I. In fact.' sm.1I home-made iab<>I"OIV !u'Nee. ,nd I give det';l, of the construclion I".,. It Ill. P01 salt as thl .i, (or, wor$l, "'PO,,,llrBpped In the 1'>011 "!Hnds.. The pile, c.n then be set In ,he bath. wilh , wore "handle' It need be. lA lob lik~ I fill or _ _ can , 01 cou.... h ...... , he ling protruding I""" the su rfacel, The jmmMSlon 01 I.... wor~ will
f".
loO '"
_'f ___
....... c_ ......... " r
....
A", " ' _ Wt·,..
.. . _ _ '" _ _ .".
__SOt<' _ _ .... . , .. _
.... '
'
...... . . -
• ..,.,.ari!" red~lhtt",~1h temperalure. ... th«I .. no •...-. to IU$l the conuoll ~.
shoUld rKOWl, very qUi~~ ly.s tM" is cl uldenbl. 110<. of hell In Ihe lu,nac~. (IIoce there 'he wortcoiltCl un be letl lor . . p'.",.1bed time which. for. ",It bath. &Ill' be HA lf THAT NEEOeO fO R A .... fFlE fUR NACE le. 30 m,nU' " pe< . . . of thickness. This III one 011 .... IIrel1 " n tlll" of lhe sail ~th _ the ot .... , ItIIo"II thlt the "".,i"ll i. bound to be ..,Hoow.v" ~oll.ct in the ltIIItIom 01 .n olf beth aod th,. muSt be • ... d OUI .. Int.rv.I • . As 1 hevI .... id. the .... i_If I. quite h .. ml .... (when cold. . . is; moll ... ",It muSt be " •• nld wilh ... AmI ,espect IS that ICCOIded to I11III1," me,,1 - ... Ch. 10.1 Ind r:lebris c.n .. di5P" leould not be used .... Iarge tOOls.. The Sltlt IlvII should not be ... then tht"--Qu.ner. lull nor thould It _ more th.n en inch lbove the top 01 . . hell'"", el8ment - Ind eerulinly Ifaould not 'Pl)rOllCh I.... top of the po •. In _ sen . . . I"goer di.mete, .od short.r dIoth would .... Ip in this r'lj)IICt. but Ihe toll of t.... t\>be.nd heating II.m.nl then becolr>ll r.thet high. S.f,1'/ precautions ... de.11 w,th in Ch. 10 .. bul r wiN ........1114 _ poinl now The ...... id is "'Or... hot I. molten brl.... Ind \'OU lJiould ~ w lltlnll proper goggles. ~ee,. ""... 11. and. cap OCN'lry to rID up" • ..,11 POI; it mull be properly
w.,., ..
CONIU\lCt\ld Ind be IONd enough Ind .....'" """'IIiI not to tip ...... , for the hot lilt will set the !loot on firl jUll . . would hol metal . Fum.", Conlrol . The .. is no method of control of • 111" fi,ed Iumae. which ~ reuonlbj, In COIot than "m.nuat" 11 ~ po '!>Ie 10 obr,in modullt."II IIame bumers w.m If,.. ,,_tits but the COIoI Ind complic.o lion would be difficult to JUllify "" the model '''111,,",. Elaclt~ lum.~ea c, n. however. be controlled ,ulomllk,IIV. ;" two w'vs. The ..1I"'t ,nd che'P
0"""
""11'
"
,,-
tr.nIt/v.' MYiI found Ih" lhe only problem
I IIIIy ... the end 01 • 3132 in. dI.m" .. rod \IQ It wHh my Ine'gV COntroller Iype is Quenchi"9 "",perB'u" Quile h.pp, .... ' "forgetfulness"! ! ~now preUy well where w armed h9VI el.eadv tef.rred to Ihe USI of I IPi" lhe die! Il101 ID be MI for .nv p ..tic"!~f I .nd on no I.",p for ,,"'pe.i"'ll. For lienbe<' pOinlS'" . w,,1I ";11'1< IempeJlI"'". but I h.v., on mote th.n one ...,.n Imy boring 10011 the whole PtO< ; ocasion, been ellled IWIY from the-"<>P Cln be c.rried 0\1 1 wilh Ih .. r,1Il-e1e11Qo.o.whe.e ' lie uN of "pile •• ' Ind forOOllen 10 cIleck lhe tempe,"u •• Handling . ~'lut.lly. you hi.,., 10 be , befo.e 'uvlng • 110' Ih.n i.Ofl wl" Cln be 10 hold lhe hOI mltll I hlvt1.'teldy m. ' 1) make • lI,ndl, Pflssing ,..1.. fInaI '0 Ihis from lime. Spiril Ympe. from the "'bli.... to the .... deod IhtoI.ogh • hole if lhe., .. one ti ..... In m.ny .nide. I " - ...d ridiculous? By no m ..... ' The humbl. . . . Fig. 28.1 R.membet ,h" when II>e .Ul...... hu m.nlionl"" lik, ,11. link of, ch,ln eln he ,lipped 0 .. · .-:I 10 use. quencll link 01 "'Ch dep' h TII. h.ndlll 10 IIoId 1l1li noM closed on ,t·. . . 1'10 l1,rring la needed, lhe pan"';lI fall ~ Sucll pl1ef11 or longs come 1ft "'. • iIIe bol1om 11 • " .. which '!fipa ,I 01 st>.pes, bul Ih" Ihown hi !lie "-I UI'" I am or V'pQUf, The hell contan' of for h ...1 '''llmenl. For sm,lIe, wo.k Ih' "'I,bora,o" . . . linv p.". 11 so smell Ihll th, "Ind'i i. almosl I"""nll_s Invw.v. s/iowrr In Fig 36 lie"", lhe 5<0 ..... ..., Un be I,POId lrom lhe boal 10 lhe P'I'IXH U .... IIy mid
••,,,Id
PfI'",
.,,'+>
ctJ.......
-,.-....
,ong,"
-, .............
--
"
......
D.
PrOOr.m .... la "OCCIsion.Ir' The ...... hell -,rCII should cover lhe Med. 01 .nnesllnll. Ind b .. ~ing lorehe. ..e adequl" for "open hearth" c'lIehan:len· ing ,ef'''ed to in Chapl't make. 101 01 speci" 10011. whQu work i............ 1Il10 h.n:leni"'ll 01 j;g..nd or who me ke • p<.CtiCI of h.rde
e. n..- ""'" oe....
h.... .,....,.,
.-.QU''''""""
"
' ... 11 ._ . ._ .,' •. ' _ "" '."" ", _ ~1., _ ..... , .a-_ ""_ _ U <.
__--
:::=-:-'" , ' .-. . ~,*- ...=. "'_.,._ .. , .. ..._,.,"
CHAPTER 6
Id . . . . . . .
..
,, ~ ---
Casehardening So IIf _
I'>awI bHn concerned ... ith WO
..
,he carbon Indultr;'11y the time il ~ ,1111 • CI"'"II of 'OPreQ.ble thidtIa. 1/16 lroell or moough .... ma. I.., ,he surface to Improve ,he Ii.,;sh. W." thid ca... Cln be , dimentiog surface and I.... se'lw ,h'"ds, If mid, Irom sil~e, 'U·' 'h .... threllds ... ould be dead h•• d unl!'
,her.
"",,,,rid. yet if they we •• tempered '0 the MI, ",'dness ' he wee' ."il1D""" of \tII pin will be f'1!duced. pe.h'pI unaccepIM*r' The Pin sIIo .. n is. In lact. made of """" .oened mild •• eel. At "," ,he pin I, lOUgh m.chined .t,1Ie ends .•bout 1 16 k>ch ovI,sizl, bul ,"" be ••ing ,urface i, Inlshed. AI "b" it liDS been c •• I)u.i$ed .11 ove •• nd IlIen IM case turned away from !he ends. down finish..... One IlIreld halt been ......CUI. AI --c" lhe pin is seen 8I'ter rehe";ng M1d q",nching ... Ii·saol. paint wl. used, Finally. II "d" YOll see tile th' ead Cut on tile ollle. end lehe • q.oanchif\g) and Ihe whole cle,ned uP.nd polished. 80TH thr',," " ' solt. despill !he lact thll one ..... CUt befot, M1d the CICher ,ft.. QUenching ...... ' the belnng .. rfece it deld hard, and tool< t"" 'eelh 011 IIIe file. The hard skin W85 sub$eQuen . !Iv me.w.ed .nd found '0 be belween 0.003 Ind 0005 lroeh Ih>ek, Thl.e III o,lIe. .'tultion, "''''r. caseh.n;lening Cln be used to Idv,n'age For ...mple. ,complex form· tool ClIn be midi from mild 1lee1 end carburised Ah &!' hardening il will have , SYriacI ha,d&!' ,h,n lempe'!on steel. It w,lI not Stan(! 'egrlndlng. by. till ,001 life will be IIIlgh,1y Ionget and il t1 I1 .0 be used only the onctI saved • lot 01 ,-""", m .... iaL Mlde from ca/botI 11" , . pivo' oin or a lithe cen". will need 1(1 be ,.mpered: c'seh,'dened _ tMre Is no need. end Ihe wll' ."Illtance will be
• •
11
'0
-
w, ........
•
••
"
11,..1.,. )n ANY "llllllon wh.,. lhe l>8<1" lubl"1 10 shoc k lo,dlng 0' w h.,. 1<>lIgh...... 1s n"dMl for Olher bul • 1 The "n'III tin'lll r...."nee 10 we ... is requir..:!. ~1IIt>.,tlening Is the .nswer: \'OIl ~ \he Iofd bHring co.. in • JI,I. to lake ,nd the surface c:onditioned 10 ......1........ C"bu,i.; ng . Th." If. Il'>r" m,in n'IIIlhod& In u". _ 01 wtlicll. lhe Klive Hit-bill'>. i. nol sultabl. 10f model .ngi"".-, Il_ .. O! In",*"" molten cyanide 11115. which Ir. let h llly POisonous. In IndUII'V lhe nul most common method I, BOX CAR BURISING. Thl, Invol~" Ih' seuing of Ihe wo';; In a he . ...... w,1ded .1.. 1 bo~ fi lled w ilh • cafburlslng mllerl,1. lhe lid. . . . sealed or ··11,11 ..... w;lh fi"d.y. The comPOUnd used 11 SPK!.'1y /otm .. I.tlld, I'rgetv chlreolll. b .. 1 w ith addi t ives 10 in~"ne ill IfIK W _ Hut1ng limes 'f' 01 lhe 01'" 01 sO. ~ 01 .0. For OIIr sm.U parU nolhing 110 elabor.1I 11 needed. , hr
"'SO
I'" "'""
bonall) Illhe mOlle..11y ob1,inable. Ao~ .boul 1'1(, by weight 10 1he ~h"co,1 • ..., mill 11 thoroughly Alteml1ively you C... add SOma 0 1 tha " Open H . . " .. comPOUnd. "K"er>il No. 1". whiclll be mtnllon,"8'"'' 5" "";11 sutriCging up lhe temperllure Th. box I, IlIowed 10 COOl. Ind th" Can be ou lSld. the fu.nace if no 5Ubse
"""or
. ""'JI
le"....
_n
_.pped
",,",lied
,'Iow
"''!.' Th is un be "he. led and Quenclled
!." ...."'k thlt sutrrcienl h .. rdn... hIS been
I .. se , piece of fOIlnd bar .nd :pId 011 lhe .oDe ' 0 Iom> • flat ,ft.. ~,r>g This ill w;th 25" nitrrc _ in wal" .nd. as seen in Fog, 38 lhe _Ih of ca.. iI Q .. i1l visible. 1lIiI .. 01 magnified by lhe "cln:ul"ity" 01 ". 1IPKimen. the ICI....I Ihickneu CAN be ca\cllleted 11 you Rke. but I .m. IS • NIe. ;tthe tl5l shows the c... 10 be "adequller' Af"/ " pan-machining'" can _ be don, . We nUl have 10 h. r Ileal. This m.y h.~a CIIIHd tom. , ... ,se<>Ing oIlhe gfain n... .... nol be il !he lime wlS .n hour Of ..... bul !l1orIger it ~.., be wonh .11.... dIng to. 11 lhe boo wll heated for 3 hoIlf$ Of mor. I would ,lwayS W".... the ",M before hardening. This .erming is *"- by to a tllfTlJ)ll
.,ched
(IOU'''.
COfI"'"
_iou,
*'"
h.I"'"
"C.rbon Tempt'.lIIre · C
"'" '" " '" "." 03
11,,, lor lhe rlllula, "one hour pe. inch of thlc:kn ..... and Ihen Quench In oil 11 tbOIil 30" C This I, NOT • h.rdani"ll _ ... bul solely di.a<:ted to ,educing 1ha gorlin $ire oIlM core. In IIC!. with """ mild IIM11lbelow 0, ' " ca
The comPQnlf'l' is lhen btoughl IlP 10 7eo-1SO" C The hel1i"ll time is short . .. _ ... concemed ontv w,th the c ... , I t.w mirllllH is otnOUgh . nd Ih. wor1o. I, w alet.qu.nched. I h.ve ,lready rwm.
"'n
F"ntdy, thIs Is lotaltv unfltlCl"arv fOl ~ ... of the thickness we ""ad and ..Idom kw thlcke, ones - bul it IS tound _et."", lhal ...,,_ c'llIng epp.a.. dltring lhe lI"ndring operat...,.,. and """""I ptKlica is 10 ""'98< 11 tbOIil 150° C 11 e.rtpIrience tnows lhal IhII is htiWy Opan·hHnh Carbllrising. Oculi boo ~ .. bu.i$ing I, seldom naeded for model wo
"
Nalurallv. il iOlermediale mactlln'ng is ,equlred it is nece""", la allow Ihe work la cool. Th,s ean be allowed in ai', bul I usuellv clap a piec .. 01 n,ebrlck on tOP to ,eduee lhe Clue slightly It is ""t critical 3t ell indeed. Ihe ... is linle Ihal is cri'ical abou t the whole PtOCU$ IMugh nltura lly Ihe more care fully the lemperllur91l are observed Ihe bettar the resulTs. An occask>nel problem i. scaling. However _ 8re dealing with 8 MILD (0< 81 moSI. medium carbonl sIeel and Ihe,e is "" need In Ihi~ Case la hUI slowly. When carbur!sing it is onlv Ihe s~in IhBI i. .Hecled anyway It is ""1 possible to use anti-scale paint. ""r a salt-balh. bul forlunately Ihe compound itself does have anti_ocale prapenie.. It I•. 01 00<1 ..... . only l>"'Ound - on I rltch81 whe
"
be pro.&Cted from Ihe action ot t' .. compound by wr8pping wire or 5l'Iim 5t~. round it. Tapped holes can be plug~~" with. screw. and plain holes by insarl" , plug .. And. 01 course. if all you oeed harden is Ihe tace of. tappel or the end "I a tool it i. e&sy anough 10 devise me8n~ t" restrict the appli<:allon at compOUnd 0,,1, 10 thl! plnicular SpOI. StH ls lor cuehBrdening. Any "5tr8'gl" carbon steel can be tartluriJed - you (;/Ir il circumstances 'equi'e it. c,rtlurise sit,,", S'&el! As, rule, however . the process normally spplied to t.. a low·ca rbon "m,ld steels or. al most. to tho ... with cartlOn ContentS below 0.3%. Free·cutting s.eel. can occ3sionally Plasent Ploblems - !I'~ inclusions which ptO\Oide the tree-culling qu alities may cauSe surface cra~'ng 1 would ""I advise boo carburislng Ihe ", mate,i als. bu t have successlully surfael herdened them by the open·hean h method. Steals speci licallv designed lor Ibo_1 case"ardening Bre .y.ilable. TheM USUally con'ein about ''lI) of Nickel, Ino object being to reduea the g'ain growth during I"e prolonged .. eating. 5"3'11"1 carbon Sttel, intended !Il)8Cifically for casehardaning by either process afe fr (080M , S in 85910/,9721 wh,cn 0.,5'" carbon. 0 .8'11) mangana .... and Er 21 (130M,5) w"ic" i. 0,15% carbo '.3% mangana": somewha! strong.er .,1 40 ton/Sq,in tensile S"angl". AIIOV .",,,Is should not be casehardened withouI detailed hea' "U tm"nl &peeilica' tions Imm tM makers. All such steel••'. "heat Irealable"' and you may well 5el "p ,(!verse condition. dUfing lh ~ carburisi' proces. if you do not get the temperal"" righl. Neve'try to caseharden serap Ste' or oHcuts from Ihe mach1ne·shop .k" They may be ilnylhing. from Iow g,aM sleel for making decorative haodr.il. I" c h rome· nic kel.molybdenum -titaniu ", alloy! On lhe Other hand. wrought i,""
. .slly identifiable by the spark tesd ~hardens beaulifullY, and YOU CAN CP8harden caSllronl Obviously you must .,..,e ,egard to tM shape 01 the castingcornPl(l)[ outlines may crack in Ihe quench. ""I hardening the end 01" plunger or even • v'l ve·roc ~ er prasent. no problems. Exam ples . Fig. 39 shows a law ellamples. t"" l!lit il a ball·joinl made to ' e place !he carburettor conlrol on an ancient molor~ar. Bright d,.wn hexagon bBr was used and finish machined oomplalely bel e , e hardening. T"e Ihre.d wu prolected with thin iron wira and w"itenIr>g. and onlv I"a ball and w3S dipped in la... nit No. L It was quanchad direct Ifter Iha second application. Centre IOP ;5 \tie cranksh.II lot a mO
pleled ,nd pan ed oH. altar wttidt the H'nged end was finishlld. It was then rahe.led and quenched. Th",e wu no d ifficulty 81 all in rivating the spigot on assembly. Top r;gh' is 8 differenl Situ81ion. This it. 8 tep needed lor finishing tile ,nlamal Ihreads 01 the boxwood chucks used On my Hollzapffel lalM. The cost 01 a length 01 silva, sleel thi. size would be pro .. ibi_ live lor Ihe amounl of work it has te do. Funher. the,e would hava been some risk of cracking ,ven if grUt care were taken. as the lh,el!ds h.ve sha,p roots and a line angle of 50°. 11 wa5 made 01 black mild steel He. hOl rol~d. not brighl drawnl 50 thal there Was no need to normali" il lirsl. It was \I'ven, sifl\lle treatment w ilh IC.oonit No. , and quenc"ad direc,ly . The cuning edges Wefe ve", lightly lIoned allerwl,ds. It has servad it. purPOSI! wil" no diHi<:uUie •. Bottom lell is a drilling jig for SOme cylinder coverS and Ihe associated cylin_ ders. lhe numbef I/Oing t.. rough t"e shop IUlti/ying the Use ot jOgs. It was made lfom Brlghl Drawn sleel wh>clt was li.S! nor· malind balo.e machining. I1 was
nc
, -... - ,......-_._"---.--...... 3. e......... ,,,,It. """""'-
.....
'::;""-
,
69
Clrburilled IOf 30 minurea In a robacco rln u"'''II • mixture of chlfCOBI and Kaseni. No I compound, Th" WIS r:Ione 10 emu.. ,he Inne< 01 ,he holes ",as hardened. Botlom Cefll .. 11 , .... g'oo.,d illw lor 11 d'illing vice, wllich was caseh.n.t.n«t ··open heanh··. r.... P"" ~ng lekt, 1_ down, In I r.. y 01 compound, Th ... de .... _ , ,pplied The.e "'I' 11 linle oc;.hng on , .... back. Ind juSt a litH. dislortion It would have been .... se. 10 no<",al,H il tlelOf' "'achin· ing (BOMS wu ulled) bUI Ihe IBUIl waS nOl sullieien l 10 wl".nl rhe making of anolher, Bonom .ighl Il,n '''mpl, 01 . spe<:ial Inrm 1001 Thi. ""1 made f,om mild 5'HI 10< no Olhe....son Ih.n Ih'l I lIad no high--carbon 01 I .....Ighl ......nd only • limlled slock 01 • fill w!>;ch could be maehined down. n.;, W" fili".., doses 01 K ....il No. 1 allowed 10 cool, and then and quench.cl. The compound was awtied only 10 IhI too/lip. The 'HUlt was ...."'..ndlng. The Cl"" was Ihod. enougll 10 pe"";I lighl Ilomng of ll1e '00 1_ 10 givl. shall>..sg.. •• nd Ihe peri",m,nc
,h.,
..,ri_
"8'"
,,,,,,",d
.... ntion.1 tool IIHI. And conl'B,), 10 ..PPQSllion, ..,ch ,000s hev. e he,de, tir,,, lu"'ing theM "Olic wood. "'..., wh~ luming menl melals, lor llIe on .... I'O -..-.d, 01 C..... H. no cooI ... t c... be used Conclulion . c.~ing is not. sub· SlilUIl !or ""...."" h,n:lening wilh a tNg Clrbon Sleel. bul. ptOC1llS which e",nl i, place from 111....., nt!"'e W. can design a comporrenl in mllerial whiclr PfO\Iide' Ihe s"englh, latigue reJistan<:e. 0' olh~, proplrlv needed .nd lhen surface ha,den it 10 give Ihe ,oqui,.d wu' resl'lallCO! Th. nalU" of llIe p,ocess is sucll Ihl! .elecl"" h.rd.nlng ean fe~ilV be appl,ed. and Ih. risl< of ClIcking i. very much l'8duced. UM of Ihe 0pe1'I heanll m!!lnoo giv!!s quil .. .d!!qu... rhickn ... 0' un to, ou, pu'pos. . .nd i. much "uick!!, 'hsn Ihrough Nrdtning. Wilh lhe III!ed for sub· MQu.,." tempering ..:Idjng ' 0 lire .ime la ...... Al the tam. t,m!!, ClS!!hardl!ning CIII be uMd for.uoch .lIi"ll$lI5 tilhe 1001' if C"cu .... llnuf demand. 0 ... /ine' polnl Is worlh ma~ing. Th .... ;s ohen no ,ul n• .cI '0 h.fde". rubbi"ll surface, br., ~ 11 IS hardened Ind poIi ........ I.... I,icl ion 101, will be 'educ.cl. The .lmO$l glaos lIe,d lurl,C' p,oducld b'I cI.ehartlen;ng il' .eal .dv,nlage In.1I such .poIicalions
.'c.
CHAPTER 7
Other Heat Treatment Processes II I Anneall"\I< No,malis;ng . anI"e·
...;ou..., hlfdened, whether by he.t " ....
......1 or by cold worIr.ing NotmMiling'" prOCI" Whell r.... in.em.1 struc'ure of rhe .,... " IIIIOf.cl 10 '·"",mal" .ft... $OM!! opIfllion - $aY forging Sr'eu
""'!eN'
'''''''in,
R.o.t Is. IS lts n.me I.... , ....se of 11,..,.. whreh mllV ha". be.n Iockld up In Ih. 61HI, !!,the, bv he" ,."atmenl or by cold forming 'T,mperlng" is. SPeCi'l form of "'015 'el ieving, We will dui .... "h lhen proe'NIS In '"rn, An""a lin\l. The .I.el will be M.rlenSl1lc
In IlruClUfe InICes'8,), 10 change rhl. IQ on. OIIfI,.ini"ll pearll" and ,ithe' lI<,ill 01 c.me"'''e. 8S ,t would h,ve been hid .he " . .I been cooled sIowfo,o I.om Ih. Inill.1 ,uste"'''c IIale, This mean. Ihat_ ""'51 fi,.t "'ing It 10 a tempe,,"u,, ho(Ih MOugh 10 en ..." 1"-, the sleelll 1'1;>0'" lhe Ir,nslormllion templ!r.,ute, and ,hen COOl i, I1 • '"l 'hat w~1 ,11ow ,he I.."'· iotma' ion '0 ""arl;le
'"
0305
In Ih. CIS. 01 low ca,bon .nd mldlum c.fbon lIeels (bortow 0.85%1 'hi' will be abou' 30·C lbove Ih, uppe, cfI,lcal, bu' for higher clrbon """ten' • "mpe,,,u'l IO/nI»hll abovl .h
lUfficIo, The ,ecommended lig .. ,. . . . . grrven ;n ,hi I"'" bl!low, (See allO fig 4 II In .ach ease .he higher lempe"'UII ....11. . ,0 ,he Iowe, carbon con',n' Nor>e is cril,c.IIG w,'",n ~ 10·C, The m.1I1 muSl be .... ated oIowtv ~ Ihln "Io.ked· 11 'h • • nn •• lln\l tem"","y" 10' one I'rou, "", Inch of Ihickne.. In lhe caS!! 01 recl8ngul., seCtions the ,mal ler dime"!ion is IIk.n, 11 Il>oold Ih'" bor cooled . . .lowIV" ctn boa COII!';ved, l! heated ln a mu lfl e wi,h • good heat In.ull1ion '0 Ihe ch,mbe, 'I m.y bor ,I!owed 10 cool down 11'1 lhe 'umace, OlherwiS!! ;1 mu", be n' in ho, a.,," or - " . 'im!hr, "'1I!eri.! which w,ft .."in I.... helt Thin. lIal saclion\l can be (0111. d belW"" rwo pre-lIl1,ed 1nsull'''"II bt~ The highe' the CllboI, conrenl , .... MOre imponanl is ,he slow " .. 01 oooI'ng, F... '"mild"" IIHI lhe piece mlV be coolld in ,i, once It has dropped 10 ..ound
C..bon. "
B.lowO 1 0 1-03
05-0,7
07_0.9
Abmr.0,9
T..... p.·C
92()"900 81()"830 850-800 B20-7BO BQO.780 790·760
Sihr.. StHI' 770·C
"
n.... mull be lIk,n righl up inlo the lu lU"eni lie rev'<><>. Fonu"., ely 1001 I teel ultlom _i.8 ..."....Iillintl. whid1 " n elded chilltV to imp'ove Ih ~ mlchineability of medium IntI low carbon (.nd I lIoyl SI •• I" The following tabl" shows "comrrntnded tempe,-,u.es.
., "'" "'" ,.. •• '" ,. " "'. " '"
. 6
02
'60
08
f ig
40 , _ _ '" ... " . . . . . _ _ _ ..
- " ............ , d . . . . .
4OO*C, but il f' inadvi ... bIe 10 quench 11 ......, f,om • Iow le"-llu,•. No,. Ih~1 WOtiI be fully .".he.led belo<. imm .... ng in. ul" bIoth ro. .""""rong. An ....llng high spud s,HI is. chencv bu ....... 10.- ,he ~m"eu, . Upeci~lIy as any .ubgquent ha.llening m.v wen be beyQnd Ihe capabilities of ,he equipmenl ....,il,bI •. H ow~,. il wch .n opetalion muSI be can .......1 the pleao should be healed VERY slowly- to 850 " C. held lhef. 10< one hout pe!" HAlf-inch of MClion. ~nd coohd ......... slowly Ind....:l, , muffle fu.lIft. I, all'f'H»' _n".I, and the cooling Cln b. b . . , etteCled by prog.eplvely taducing the power Input unlil it hll '11!en 10 .round 550" C belo<, lurning I, oH completely Notmlliling . Aher !orighl--dr'wn , To reform and tefine the ",'in Ittuclu'e il is .g.in necE'Nry 10 ,&hUllO ,bcMI lhe cr,lical lempe<.Iu", bul 10 • .llhet higher deOtH Ihln is . . . . - 10< ,nnllbng. _ielly 10< lhe high catbor'l "eel..
nw.,
10·C
'"
'00
up or down f.om the . . lempe"lu,es will terva. Tha temperature mu" be m,intalned, " in IIlI Cl50II 0 1 1...... ling, 10< one hour PI< inch of IIIClion. and the eooiong must. again. be
....
Fig. 4 ! $I>ow, , he .nne,ling Ind no, m.lislng range on Ihllron-.::.rbon diag,.m Sire .. Relie f, Cerllin rnanufKlurlng "'OC"5oII1 induce conside,able Sires", w O/h,n Ihe metll, In ~"ticul.r col(l dr_ing Ind w !tlding The Io
.i.
.. _-.,."
. .;.: " • . _...... .. _ .. " ... ,,"u_;_:::.':::'::::.;;: ,___• ,u....' , ... __ " '.;'. :"';, •.___ (I em referring to the smen pin, uted In model •. not to home-m. de bfiI
..,.
11) Scaling. In all the ,bovft O
toma surlace Kaling is to be e ' PlCled 'nd This c.n be. nuisance. It CIOn be pt'e-""nled by lhe use of ~n l;-lIClle Plinl.
......",...
binding with wi" Ind ancuing in whiting. or by the UN of ch8rcoa l ln Iha muffl8 if the la n " I1 uMd. However for am.II,.."11 ;1n ingenoou ..... Ihod is dellC. ibed In some e ....... boob. The ","s to be "'''ed I f a Nt in a ba. "lied with 0IIi1kl(! lime fbuiide is broughl bac k inlO Ihe more deeply
,
tempe.ed '-Vlon. Thi' applie' ell>8<'i,lfy to W(jE I)Iy TO .. ldarftt tools IS well. When this III.,pen, tll.,. is no oplion but to ,ah .. d.n. It might be thought tllel il would b. n.cessa,y only to 'eheat . Q.... nch. Ind tempe' Ig,in, Thl. Is well enough with "COiYse tool. mldot f""" ,eill""eIy low carbon IIHI; I Iteet my P'C.... , _king ba., .nd ..... ;1.. lools in thal W.V. But it.,.,.. I.., to ,ena,detr I lIigll. carbon ItHI tool In thi,I.&hion lhe re""lts wm ... bII.l. be di~ppointlng ,nd yOU m.y IInd the t lhe tool ctlekl. WI must '"'Ort th. m.tel to thl condiTion It was befoi$ mU .... 'lilt It Ihould be IuIfy .n....1ed IIrs•. 1h .... " 'Iady dotalt wi.h the JIIl)CeH and lhe", hi no IIHoII to repel! 11. Howe ... ",. I COIn MId a .afi.... • moml. If The 1001 01 som. ImpOrlance is 10 be "herdened I1 will pev 10 ,,·tempe. 10 abouT 300·C t)e/o', commencing the .n.... llng ptocess. Thi, will ,flacl an .Imost complete stra.. to the struClu" and I he ........... , hid. 1001 Cf.ck wheri this hes bHn toIIowed. I recommend ;1 llrongfy fo< those tools lhe.. la conside,,," dillerenc. betwHn Ih. lempe. In Ih' ,h.nk .nd in the pplnt h I, only nacusary 10 heat up .... ry gently 10 "blu.... lllow 1110 coo! iuS! 1 liu ... and lhen 10 proc: .. d wiTh the lull ........ inghe.1. III Hlfd ... lng Orn.u"...1I1 Tools. The MOm,menlal- 'u,",,' h •• , JIfOIl'!m nol mat with in most othe, typ\II 01 luming. The In compri .... the CUl1,"9 of lairly deep p,u,.nl on the surfac. 01 work pr .... ~iously lumed by no,mll methodS to an ecc""t,ble .... pe. The linal ,H\lCt depends • nt" ..... on the ,eflection of Iioght I""" lhe multit ..... of lleets so Ioo",.d -.nd willl well •• lQjled won. llmosl cIIullng rwfIK· tions COIn be seen on , wood lite Ebon'(. M
"h'
1I'"".k,..
wh",
"
HI. prOblem hi IWOioly the Indsed dacorl!ion COIn be polished. suriac. ",usl be ,eftactivI witll "tool IWsh" This ",rface lini-" COIn ""''' be bell.' III.n Ihe fini ,h on Ih' 1001. and tor IlIi' fla""" Ihe .1II'Plning of Ihe 1001 I. ta~en 10 wllal might 'ppea' 10 be exl.,me limits, Afl e, forming wrlll nQlmll g.lnding melhod$ ,nd I fine Indi. lIone the surf_ os "rough poIisI>ed'- using ,,",.d " " " " .tOM. 1'" 1001 being held in • ~;rl jig It'" "Gonio$la l"l which ..., .... ,es tllll both t'" CUlling .ngl. end tll' "pelletn angle' ere Iccuralely lorrnrtd. 1I I. than lapped uslng the Iin.sl oilst_ dust on • bra!lr l.p. ,nd finlOy POIislled I.,ill u:ling the goniOallll on In l.on I,p witll J_'Ie" roo,r.ge, Pfoblem hi ,11" modeIt llIe 1001 mull ,.m,in &ha", Ind t.enc., III,d OVer , long penOd - and 'flY Iou of sharor- c.n be 1.1.1 10 llIe ,IIICI"'-&s of the won. 'fhes.e lWO rlQuireman , s. !!nUI g,.,n ,ill .nll ml.imum hardneu. c,nnol be .chl..... d witll Ih' norm"1 carbon 1001 steels lend , ... ,n IISI 10 with IIlgh-lOll
n..
n..
lUbseQ ... nT t"",pering should be .. mild IS POSlible 11 ,he point - I do no mort man boil in wit .. fo< half In hou' for
cuning "Ime 1001•. but sI"'-tll1 1000S muSt be tempe,ed .lleest to s \faW in Ihe &hank. Altematively. wilh "511 ... " SIHI" • lI'ein •• lining p,oee.. Cln be CI,rirKI OUl_ ,nd tin will glvI Quite satisfactOry IflUItS _ wen il the purlstl will SI'( "SI~I nol .. good IS' genuine HoI'18pffel'" After "'Icllinlng the pie" 10 Ihe requl
w,
"wild) conditions c:ont.isl' of grlinl 01 pe,l1il' su.rounded by I ... is COISlthe selaclion oIt'" beSt lempe'8!ure is the matt Imponant pen of Ihe 1".lm.... T Th. ml. tu,e 01 lempe,I(! Merllnsite and ferrlle crysl8ls Cln be edjul1rtd TO give lIigll •• atllnglh. high yield point. bene. ImplCI ",isllnc•. Ind 10 on. Fig. a I shows IIIe eIIacl on a tn>iCeI 04" COIrbon 11",_ .nd .,.,.. wiM notice 11111 ."'" hi I dill In ,''' Impacl resi'''nt4I Ilrod Impacl Telll In the middle tempering range Tllis need nol vou 100 much. " it is SliII constde.ably lIighe • than 11111 of Ih. unllea,·treated lIe.l . To givl'.n ..,mple. lel ul conlider OUr old friend ENB IOOOM40 In lilt BS 970 1972 nom~rel In the 1>OI""lised condilion ~I ~ies would be lB TiSqln. VTS 27 T/lQin 'I"..Id: EIong •• ion Iduc lllityl 2B" Ind In I.od imp'CT IIs's,.nce fig"" 01 15·1 11t.lb The metal is Austenised by heating TO B30·BSO·C fo< 1 hou./inch. ,nd !hen Qu.nclIed in oil. The IImpering temperl1u" mul' IlIen be selected ..:con:Iing to ptOp8r1ies _ need. For mui",,,m tougt..-.s Ind the mosl .rdUOUI f., igu. Ind sI>ock loading condillons Ih .. would be belween 550
.0""
wor..,
t'"
and 650·C and then air cooled. (Note that lemperir>g salt will no. opera te at this ligore and tha worl< must be daM in 8 muffle). At 600·C the UTS woold be around 4 2 T/sq.in. Yiald point about 28 TI sq.in. Elongiltion perhaps 29% - not a great che~. But the impact res.iStarn:e hn gone up to 80 f1.lb - around lour times as grea l as belo~. The 18tigu8 rlOSt.tance also will be improved. 11 we tempered •• 400·C we woold ,oisa the UTS to about 50 T/sq.in. but bath dUCtility and shock ruistarn:. would be IIOSS though s.iII ben er than that of the nor· F".... 4.2. , ... ",
malised 51<.al. For completion. the normalising temperature is B40-S60· C. bill il YOU have EN8 whlcl1 is b'ight draw n Irom the Oil Hardened and Tamp",ed condition 10.H.lH . in the stoc ~ holder"s list) it is , in lacl, in about it~ tougheSt condition. woth a yiald point 01 around 46T/ sq.ln . and an Ilocl (,gu,e of about 60. You are oot likely to ben 8l' this. However, mOSt ENS is $Oppned to model er>ginee .. in the br>!iht drawn state with no heat uaatmant. and no,malising mav be prudent be lo re WO
, " . ..... ' .. ' ". _ _ _ _ _,.' .... _oI~, ft'_
~,
n
70
_
_
... _
.......... _
!lOD IMPACT TES T FT. L B.
sa 50
.
ULTIMATE TEN SILE STRENGTH TONS /SQ.1N
.
:
-z
""'. "
1\
4 300. 500 200. • TEMPER11\G TEMPERATURE- 0(; .
ELO NGATION- "I. (DUCTILI TY ).
6 00.
Similar trealmant can be ca"ied Out On St all •• eel w ith a carbon COfltent • 0 .2%' BUI it i. MOST impoflant t you know e • • ctly what matarial you ". trfNItir>g and whet traatment 10 9ive 11. pnron unat . 1y mosl lI,ms now send .hei, ,..orI< out 10 SPecialists and published data "h.rd to cOme by. 11 the sleel can be """tilled with ~n ··SAE number"· (Society ., Automolive Eogin ....",. USA) then tllh e, Iha SAE ·· +1 8ndboo k·· Or 't!Iachinery's Handbook·· cen give some guldanc • . Th. probte m 10' Ihe model -"Ill".,.." Is in selec.jr>g the requi,ed ..... pa'lng tempera ture. It Is on thi •• rat her ...... the inilial quenCh . that the linal "OjNlIies depend. and if ~ ,ang" 01 ",",p"ring tempe ratures is offered this ...... nt5 a puzlle. Perhaps YD
-
Handbook·' end in App.l. ,nd I would sltor>gly recommend that )'OIl start uslr>g thase new number. - 001 least bec.osa steel Is jusI not be ing mttde to SOme of the old EN number' a ny more. ('Thll includes 8 faVOUrite 01 mine - l% Nidgslrom wire which is aheady ha,dened and lempered. Th. act of coiling them round the mand,el sua5S8S Ihese beyond the e lasUc limitlthe IIPringmaker"s term for thiS Is ··scflgging·· ') and Ihis actually improves the strer>gth 01 the ma'a,ial. Howevar. there are occasions when this i. just nol possible - .he gauge 01 wi~ i, too .hick for the diame le, 01 the mand rel. In Ih.sa circumstances it is necessary to solten lanneal) the wire. wind th' spring. and than harden and temper 8g8in. Unfortunately wa seldom have delail, 01 the Sleel CIf which Ihe wi re is made. It may lie betwaen 1.0% cafbon. 0 .4% mar>genese .• nd 0.7% cafbon. 0.8')(, manganese. It should be annealed al abouI 780 · C; this is nOt critical. but the .mall mu. of the wi •• g some part 100 hot and It i. lmpossibla 10 be Su~ of even heating. Set Ihe spring or spring. inside a stoel 0' copper lube and heatthi. to 780°C Irom the ou"ide .. eventy es you Can. The springs can then be tiPQBd Into Ihe ";I-bath - the,e i. no need 10
n
It) Ault.mpe" ... g .... d Mart,mpe. inO ·
QUENCH LINE,
SKIN
111''''''"
•
MS MF
....Theft". for 110 .....11 • mH' ClI m.,,' .-Id I!lfIng 1.lIing ICllhe b
ficien! v.... musl ngw be veiI and lhen hold I1 I... the ft,m, III !he ~ril I.mp un1il ,he oil Ignlt.., •• ..,gn . . it doe. 10 mow It IU
1'1,,,,,
,.
"""""rtg.
---
.... _ .. __ .... _ ou' ..... _ _ ... ,
The_ .re 'alFly advanced method. '" hll' ""unenl, much UMd In Ind,,"f'(. M,,_ "",pe.ing i. 0 1 lilll, u.. 10 'he model .,.,ginee" bul Au,"mpering CM! help. Ilpe CI,11y wllh Ihe ca.. wet>eve JUIl betn _ uSling - the hell "lIlm-.., 01 .... ,11 "",ng" Th. c.... belt be under· ~ood by re'erenc, 10 "ew di ...... m .. HO· 43 shows the no,mll p.oceso CIf ctUlf'Chlng end d;,play«l on .... '"$" CU,..., The ,......,..-ing period ill'OOl. 01 COU"",,. In eny w.y connecled wolh lhe tirM ICII, 0I1he -S" bee ...sa ,he u_· form.,ions whic:tl ClCCU' . . . nol lhe NmB .. lhose wilhln lhe -So The diag..... ........... a high lempe,"u" IImpe', .. orugit. be uMd 'or • lIIfinO Ind \ha will end up .. tempered M"'en' .. " 'UGng. 10Ug/!, bul nol IS h .. d " i, nEl !'ld for Wtti"llI00t .. In 44 ,he ill quenched f,gm , aimil .. high tempe'"u,e. bu1 ;n • hot lilt NII'r. IOmtwhe.. beIW.." 2BO°C In d 330·C, nOI cold wit.. The Clutnching 18m"",aIU" I. hi9l\e, Ih,n Ihll " which lhe M'M,nalte IClrma, .nd Ih, ".nrlo,mllion GCe",. "ong • line of
.• __ _
ft,,,,,
spirit .nd "Iow Itle oil '0 bum awa ... Quench In <>iI when the name goes 00' .nd lhen repe.' il ne<:u5IIry. IS il almos. Cln.inlV will be for he • ....,. gauge wire, It .. .Imosl ......"i.1 ICI make a lrial spring r Ihil procedu.e;' to be ado!Jted, The sail balh i. ,he ideal melhod. III eou.... Thil gi ...... bsotu'e conlto! and 11. Ilnle wire "stI •• v" - like en umbrell. upside down which h .. I<>~I its cove, - .. m,de • numbe, 01 spri... gs CB ... be tempe •..:j .t 0fIC •. The.. is nCl need 10 quenCh from ,he ull bath. bul once Ihl 111""" h .. cooled OOmewh'l i, can b~ Imm" ..... In hol wale, ICI rem""e Ihe ni, adh&.,,,,, 10 h. An alterna,ive Slnd-balh . • pr~ .. which c .... bI! very effeclive 1"' lpO'lnO" The bed thou\(! ba 'J irlV deep .nd kept lu,ned abou, IS I, is heated. A "" pi_ III .Imil., brigi'll 51eel is ""' 01' lhe sar>nduclor. 10 Itlat ampl
I. ,h.
0' 'ppa'''' ""
....''''i.,
rog
~
. .. ~
se..,
CO .... tlnl tempe,.!u,.. as It pas". Ih' OIIgh ,''' IWO borde", of 'he "S"_ Alter • ,ime which depends on lhe perl<>d A-B. .nd Ihe lize of 0.0, don'l III the, WOff'( you - il doesrt·, m.lle, " Ill) which h,s ..... f'( limifar propanies. The 0'"1 _ .... ,age oI!IMS me,hod ilthal the,e is no lherm,l shock during t"""ormll'on 10 M.m"''''e (or B,;,.;" in Ihi • c .... la Ihe" i. wi,h COrtvenlion.' quench'ng. AlJnO$I all commen:i,lIy made Spring, - .nd such Ihif>9S as f1)Il.p;n •• rod the like -.ra AUSlempe,ed in !hi~ W1lV The MttnemfW'ing process is snown in fig. 45. JUS! lor explanation. as i,s rn.in " .. i. when heat lraallno very thic~ CIf m ...lve components_ The piece I. quenched f,gm Ihe high 'empef1lIU'e in I
_ _.•
".1I
,. "'" .......,-",.' .......... "".' ,--. ~-,
. -""... ...." . , ,.,~
CORE.
'O!
TRANSFORMATION AT CO NSTANT TEMPERATURE _
"'IN MS. MF
---- _ _ _ _.i-.- _ /
- - - ••~.-
SALT OR LEAD
BATH
TEMPERATURE. ____·BAINnE~
"
ull blnh n t>e10<1, but Insl8ld 0 1 ,emaining lhe,a tor ,.anatorrn.tion It it; liken OUI '5 IIOOfI 11 It hll reached the lemper ba.h tempeIeded 'or nDfmal I,moe,ing 300~C '0< I lIOting. ,.,. soon u the worI. 11 is IefI thera 10< • lenglh 01 time which depends both on lhe rype 01 st... Ind its thickness; 10 minute' whl even tile he""', lIOt'ng •• nd 30 minules is .lIlket would be I'IHIded 01 hell t'"ling ........
I'" _...
'
-
n
. .
",me. ""
f .... . ! -.... " _
t
'"
• • • ··r...... _ .. _
... _
...
largtl cranl
""!\IC"
IImpe'.
A lew Pflteticll no,,1. Fnl. ' his is HI .. Treating p'OCUI. not I 10< he,d,ning On,. AI Au.llmpe'; n, ' empe .. ,ur85 below aboul 2S0·C t, lim. required 'or Ihl translo
,,,* _ ...
_~
__ ,..
~'"
Cd . . . ' .
w.
,,,.
,
lor "Srowning" n 11 IIItI i. 'el"lvely u .... - It nl<:"...... 10 heal the componenl """ 300·C However. 'nul" I.... Ih,n .., isl.Clary unleu the pr """IOtl' wor1o:: is well done. In ,''' ca.. ....." lhe pan Is to simul,.. "fine forgeworlt on lhe pro,otype il is • m.ia.ke 10 worI< lot • ooIiotted finiott The .m_ should be r.... man. IS ptoduc.-l b'I' I IDfMY motion 01 In .br.Sive_ ,he go .... dtperoditlg on tile siza 01 the ~I The In"",,1Int painl is 10 ...,,,,., thll lhe IUrlltel, onu Pflplred. I, fret! 'rom oII.nd ",. .se .nd 'SPeCi.l,.,.. fi"ll"r"P
'h'
rCO RE . SKIN - . ) .
IImpe,"u,. ,nd will eolle<:1 i" t of the bath. This should be from Itm' 10 lima. bul lot lhe I u.. 11 it. Pflrh&pI best 10 the IImpering bath II.ogetl_ much H T....1t has ... , in t ... bII,h 1"0 Interfe .. wilh helting. As I rem"k.,;l ., the beginning. I..... tpeei.,lsl proc:esso!1t. "rod do need I Querw;hlng ba'h_ Mo
,c TEM PERED ~~MARTENS ITE
TEMPER
deg,uslng should be followed by washing wilh hot dllI' llIltl.nd Wlte<. end lhoan.1t do-ied, Ilter which il should be Itendled only with clean tilSUl ~; the . acid It.. g ..... used b'I' jow.'....... is . , A ..,rnt la"", is besl to. !IITt.1I !MIttS larger ml"t' be ""',ed in • IIaOd bed 01 in ..... of lhe improvised muffles ,It udy "fe
ft'''''
0'
• m'''1t 0I11I1e.
In .It cases ,Itet healing to blue lhe pe'U It. Quenched In oil, nol for "'" ....... lIurgical "I""". bill becau$l 'his providll QU!1I .n 111«1"'" rust-proofing. TIle combtnatOOl' of the <»:id8 layer and Ihl 011 MIfTt, 10 rlpal cOtrO$ive lumn. A, 10 coIou, thl, has 10 be w81ched ,.lrtv c.re!"Il~. IS Ihe "llnls' of blue ' ollow ve'y elonlv, However. I find Ihat 'or wor~.hop tacltl. (whtCh I ··blu.·· 'or pr ........,"'" rl1h., Ihan .ppe.. lnce) a sh.de deep brown it; nol unple.slng. whilst m."" 0 1 my "'.... urtv 191h eentu .... ,ooI5 ... '!f,w eoIoured. They .,e nol cerbon ..... lempe.ed. bul loo!< I t 11 ' ....... h .... bee" 10 I,elled. BI..:bmllh'. O~kIe is ......... 601flcu11 10 Itmul,". Thi. hard. tom>SIOn it the result lin lull size) 01 soml lime 11 forging he" t1 OOO" CI coupled wi'h for"" worting III piece 01 mild It eel it; held 11 Ihi, lempennure '0< any length 0' liml to".,. gr'l" g,owlh i. inevitable, It
0'
..,<1_
''''''"11ft
"
doesn't m.n•• il T~ p~ Is being lorged, I. ,hi, will r;(IrrKI mlnera, bul il is Oilfteull 10 do this wilh model p.ns. If iT is PfKIIcIbI", following procedUf. will lIiv. lol ... bl • • nul". Artlnll ' Ih. mII .... l.clu.ing prog •• m.... SO 'hlI Iny ~n. whid> mill" leg joum....nd c•• nkpln, of • c •• nk.h.f,) c.n bl machined . ,... ,he ....1 blacking i. done. B.;og the "1orgIof" ~nlo ...... end ~al '0 I>riIlI\I «CI ,.,I,Iled wllh Ih. "finish", no.m.li.. Ih • .,••,.1 ducllbed on P8ge 72 Ind Then Clrry on wllh IhI m.chin;ng "kl"", uN 001 10 damage the ~nlsh. Nlw •• ''''' I1 yOU c.n . flK I .nr aclull toroi""" so much ,,,- beller (11) forei""" h .., perl\apt:, 'l>POSite 10 dell w,th ,'''' now, hltving IuSI remarked on the ditflcully of forging model compr:>","ISI Mos' boob on -1'''''plflng & HIII - or nun , ,oot mUSI be CI.nked. or • fIy-CU1l1r needs bending. High CIIrbon loot 11ee1 muSI be IIeId 10 I.irty close IImplf.lu.. ~mils whilst Io
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1IIgh,,,,,
"
IOSOOC. ,nd lOfgl"", mu,I Slop when" I,ll, 10 .boul 9QO·C, Th... lemperatures can be used .ighl liP 10 .boul I.""-c_ F", CIIrbon .!'Id ,trov." Includ"rng siI. .... lint, ,he I'lT!PIflllU" should be som. SO·C Iowa'. bul Ilia higM< Ilia CIIrbon conI ...' lhe ITION CIIN muSt be leken ! ......:MI 0VIfhe,""", Mr ,r, melll"", il dow ... for deraIled InIl""'Iions in lhe uH " blacksmiths lootl ,,.. Nade< is rnl.. red " one of lhe m,ny boob on ' W'oug'! lron¥t'Oon) is u-'ng • 5 Ib_ h,mm .. lhough my ,""", 11 56 Ib .. is '81her ligl' 10< such work, (9) High SjM,d St"'. The h.r(\e";ng ! high· 1fl I I ~ loot-lleel Is 1I.11y I>e ,ond ". upaclty of Ihe m,jO'ily of mod~ eno"-.... To begin with. lhef • •11 co' side.able yari"ions in "toy .;:orll enl ',ngi"", from 0.5" 10 1.00Ii CIIrbon. 0_5~ 10 4.00Ii Ch.omium. 0 10 18% rungsl"" and oom. with 5" Cob.II -.nd Ihev m'Y
vary.ng PlOpOnionl 01 Molyb.nd Vanedium IS well heh I ""aunenl ,nd an nol good enough - ,i,he, cr.ck Of it win nol be herd
1,'"
'0 I
.. nge
by- • I.ir!v ouick heating
:
~,~;,~.200 Of 1300·C depending on lhe MOSI Cln lhen be cooted in '".
IOMI 'O
I1 don. befonr lhe loot has cooted righl down - lrom perhaps lS0·C. The Iypic'! te'"9'llring I"""",.IIU .. ia ,boul 5SO-C. bill In some CHlS. espeQ,lty for !OOII _iring eonliderlbl. loughnuI (for roughl"'" worI< on CISTings "Iel , .. ""'Id temoeacl .n.lysis i.lr.nown, and lhe worto:shop has precise lempe.llure control 01 lhe fu.n.tt. this WOfk is btrst ,,,11 10 Ih, specl,Ii". Eyen h" will orobablv decline Ihl work unlus Ihe source. IVpe. and gred. of metal I. "acTty known.
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CHAPTER 8
,''''!
The Measurement of Hardness I, Is unli~ely 'hi ' mlny model engineers will h. con,.rnld w"h ,he .,lu.1 me'SUr,menl 01 hardness, 001 il 1I helpful '0 know HOW 11 is donot w"-" faced wilh one or other 01 ,he ........1 "h,rdness numbers" uHd. The ml,n d,ff"tC\Ilty is in de<;;-I!ng 1...,11y whll 10 m •• su ... for not ...... 10 pUt on , seelt. It is I.ir encMJgh to Uy th'l ItHI whi<:h brllkl unde< 50 10000oq.in. is -twN::e 15 strong" IIIhlT wt\!d\ 1.111" 25 10000..,..in.. bu' w. Clnnol b. 10 d.lin,le wilh
·· H.. d" ...·· I.
hardness number" Mlner.logists d
·-_.,cher'-
•
The ma)orlty 01 h"clneA les'ill9 done tod,V d&pInds on .he r,sis"ne. to "... ,rr,llOn oIlhe met.l. In The B,;,..,III •• , (Fig 46 ) , hard " . .I ball, 10m", di.m" .. , I, imptalMd on thl Speci"""n "f ...."1 undl< I load 01 3000 kilogram, (abouT 3 lonaf, di.met .. of lhe im~uion 10 lormtrd is "".sured us;ng I mi<;rovope wllh In ;",em,1 K"le. From this ,he ",rI.el .... 01 lhe Impression ... caltultted. end Ihl su,f.el .tresS obtained by dividing JOOOIdiellled kilograms/Iq mm, This IHl i, limiled 1" lboul 500 B"nell numbo" 115 above Ih; figurl The b.1I i,..11 dl'10"'_ For haro...,.., ,.... .... Thod and prlnc,pII of Ope-rl1ion If~ Qui' e dif/,,,n!. The indent.., w.th. ,adius 01 O.2mm . is firll impressed inlo ,M S!)IC'man under ,101<1 01 I OI<.g.
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This I ..... re, il il linnly . .lied In dtt ~lmIn and thll lhe spe<:irnen is ttC\Ire on lhe auPPOrling arM1. The dri.1 itIdICIling 1'" dep!h 01 the Impression is then ltro8v Ihi, alone: lhere i, no ,"or dui '0 "Sprill9" In ThI machine frame or due 10 "1081111119 down" 01 ,he spec:irnen. UnlilUI allovs.. The "A" scale is ustd tor e . tremelv h"d $f>ICimens.nd for 'hln, hlfd m,teri.1. The advan,age 01 Ihe RockwIII ",I ""er BrI...llls ,hlllhe.. is no nead 10 "",,,,r, IrnprHSion - ,'" h.rd",ss can be ,,1<1 diractly: il it. lherefore, pr ... I... ed for "Pf1XIua""," 'esling. Funher. ,. Iht Indenl .. eln pe",I,," even hlfdened 11'" IT an be used tor melen"ls beyond
,"ess.
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tu ....,.". the \lOP numbtro lie vefV cloll<:
-' the f1Inge of IM Brinell. The
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,Iy.
h a,dne" comp... ,a. and must be rlte.lib ••• ..:! I.om lime 10 I,m •. Both the .bove m,~ •• visible Imp.n!!$$Ion in mll,ri,l. Th, Vk:ke,.. Diamond p-/' Imid (VD P) '"ling mlchine Fill. 48 uSH • IQU,,, ~ted dllmOr'ld py' lmid as
'h'
Ihe Inden,"., wITh In Included engle of 138"_ Tt.. Ippll..:I Io.d Is u.u.11y 5Okg. but can be .h,,1f(j 10 ... il S!>8Cial condi· I~ leg. thin ~ ....ns Ot ..." hard ma um.l]. It !hi, iI done IM magnihKle 0' the ~ be .,••..t. The "a<;tOS$ eotnerS" d'mmJiOns of the imp_ion ,re menul1ld end lebullled v.l .... of 'VDP Ha
mu.,
to .he S,;""'I 11ard_ numbet'. SO 11\;111 "visulliullQn-' I, 'Hie< than with ,.... Rock .... " Kal ... The' m";n dislK:tvaMIll/I! o/lhe Vie. e .. machi ... i, Ihat the impo-es· IIion is ....... sm.lI. toO that specill suriace Pf'IPlI"non il .equi.ed !of ",ally """mato wO lesll mull be mlda In Ih' worb _ il e_l" ... Naly uMd In IIHIworks fo, menu' I"" Ihl h'tdot .. of rolll In Ih. mill. 11 I"aves almOSI no Impo-a..ion al .~. bul
,.,....-.ne. - ""..... n..
ca,a doel hIYa 10 be lak.n 10 avoid DQUncing lhe hammer on Ih. sam" »1 _ mort Ih.n onca. lor In. previous 1nl w,lI ~ wort.·hetdened lhe surf_ . The co-rell'lon bel...... n Sclem. of tmp,eulon . •nd "11'"" ±z.iy It low ha.duII - balow 220. Wi th hltd malll"'" the fllel thltlhe BrineD ball may
dillOl"\ Ind tt.. V;ckers di,mon.iml1e1y 100 pOont. on ' h' Vock"'ICIIe. Th' lable of compa.i...... g.ven .1 lhe and of the book is d •• wn I.om • ..I po-lPlI,1d Jointly by Ih. Am,. lean Soci.ty 10' Tuling M,",iall. Th. American MII,I. Soclely. .nd Ih. S ociety 01 AUlomolive Eng ineefS. b UI Sri lll"
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S tandard No.S60 - obt.inabie !rom mOlt libra.i,n - allO gl"u tomlNl."ive taflju. .nd lhese go clown 10 som.whll ~. hard"" .... G... t c ... mu., be ,a~.n In comp.ring Ih' hardn ••• 0 1 d,II", n, claHe' 01 mll.riall; ,he l.a th" {1II.l a stH"! .nd • heal " ..,..:1 aluminium llloy have , hardness number will charK'ariSlIcs 01 ,he TWO 0fIII may well be much Olt-. Th. h ..dn..... whi c h may b. expected from varioul cIa_ 01 " ... depend ""'" mllch on lhe precision of lempe,"u" _trot the ."-..",,,- of the quench and. In soma c..... lhe ...... of lhe 'Ut specimen. The flgu ... given In """"'acIU....• ~I;on . . . . .IwIYS obt.inad from Itanclerd specime<\s. not worttirlQ I"he ,ooIs. Ho...... ar, ,he IoIlowing m.y give • guide to ,he ..... quenched" .111 • .
.efIttc,
,.11
10 4 3 Rockw.1I could be machined It about SO It/min. and I Nich l-Chrom •. Molybdenum sleel, h.,deMf' -wog: ,l1li h.rd.-s il nol .. high .. " should be - tor a h'gll Qrbon lleel. lhat '5 Fine fil .. wiN cuI .,. ..... Of even purJ)le. lempered carbon I tHI , bul should not mlk. If'I ilT\9f''';on on s"aw-colo,,,ed 1001 pooinll. 11 lhe WOf\
.'Ioy
.._c"",
1 ,1- 1.2C. 0 .35Mn. 0 45C. (Sil"" 51,.11 Chrom. M,,."'1IfI ··non-sh.i ....·· di.II .... Non-I.mperlng chl..I,"el 22'11; Tung"en 12'11; cobal t high _ed "eel 18'11; Tu"ll'''n High speed 1,..1 ~ile Steel. 1.25'11; Carbon The above HIIU'8I will. 01 COu.... be conside.ably mode.,ted by tempe,lng; to. carbon 51eel IIIh, toot .. tempe,ing '0 150· will d.op the hlrdn," by no mo'e th an one point on lhe scal,. ,nd 200 · C by twice a. much . C,rbon " . .I tempered to ""blue" {Jl0· CI i. jUlI machl .... fIj • . " , Rockwell " C"' fogu •• In Iha '1II1on of 5656 At the otller arid of tllll SCIII,. , ...ooning mild 51H"!. mlChln... ,.. " 200ft/ min. w ill have, II,rdneu equ,vllent to 1 1 on lhe ""e- ICIIa (wf'lich 10 not _0PI'-1I to m.III .. 110ft •• lhis; die BrlneN figu .. would be 180-1 8 51. A ' n; Nic'" 1 1" Chrome I teal. oil quenched and tempered
"'
mod.,
10 used. Th. .nlll""". should nol. 1Iow",... be 100 concerned 'bout an oo:Id deg ree differ.ncl on ,he Aockw&ll or Brinell KaIH. Of I .... equival'nt on IIIe Vlck.... IOf 11 11 qui" IIOfmal to lind , difference 01 one poinl on
A oc:~ w"'l
··C ·.
30 divllioM on tN Viek.... between o;t;fierartt 11511 O\Iar ,lie CUlling lurI_ 01 !he ume tool , These differeroeel Ire INInly due to ··.-oar;.... nl" '"Ot" in ....,ing ,he microscope or dill. INInly 10 d , l f _ In f\n;sh " the point of m .......· mant. ,nd IMrtly 10 Ktull hardne.. ditI....ncas So, 11 "f"OU _ on-,*" , " ... which hardens 10 67 . ,nd lhe _I you .-mally USl ' only" 11"'" 66 dont roo ml.>ch l Of
...rI_
'NOt...,
66_67 AocI
52-54 6 5. 66
64-65 68-69
COnGlu'ion. Th, difficulty with hard"" •• numbe .. I, Ihal lhough we know. wl.> · jectiv.Iy. whit hardnes. is. and what it doH. " il VIfY difficult to devise B meens 01 .........i"ll thi' qu,'ity. By conven lk>n th ....rlac. st .......... eded 10 QUse a n Indentalion uncle< • known load ts u$lld but thl. cl..,.,.,. hIS Iimilllions ; . m., ......, which w a. ""ry brillla would nol ~, an Indent., wlthou! Jj)Iinteri"ll. However by CUstOM Ihe 8 rintt1l . AocI
"
___
CHAPTER 9
I
Home Construction of Furnaces
UST 10 '/:;10'/4' r SLOrT F'l..OJo4E ,
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G., f i.lng. I I>'~I II.eady refl"ed b.iefly I<) tl>e "'fIlcultln whIch ,riu WiTh gas li.ing. Thl de,lgn pi , cpmbustlpn chlmbl' dp., 'Iqui •• ,,,ICi,'il\ knou' • • . • nd of , bu, ..., ...... more. IIId • 101 of expeti ......'" The on:Iin.ary "Iorch~ -.ir or HII-blown - it intended II' prOduOI • H..... whleh CIOn be direc.ed .1 the worI<. wtr...., to< hllting I muffle you r>Hd one wtrlch dilt'ibutn lhe .....1 sideways ,.th.. Ih,n ...ruc.11y or ",t • poin!"' The ··O···II"I'j>Id mulfte referred Tp on Plge 57 it normlllv uMd on Ihe Ulile brlzlng I>"rth_ which 1>. . I fi .. a'e siled.o ,hl1 th.v CIOn be pund The mulile 11.. 11 II' dl.act .he name PIrty. It I, moll eliacli"". and when I was "on Town g .... I m~ considerable UII oil!. 11 you ' " conIldering. muffle pi till, ..:wt. built 1nlI" home-made ...."h. then • !ell.. tp Willi.m AIldIIy & Co .. Aleou Work •• S,pu'po'l on Sevlrn, Worcs. OY 13 SAP should bring you !Iellltt of lhe ....... m ... , uMd. to(l8ther wilh • quOlllion to< IM muffle A ,m.1I "muffl.n.", I menlionod on p8{II 58 and in f~ 31 • 1m,II TUbe fumllCl which I rig up from 11.... II' time. HII. 50
''''''II&d ••
gives IhI d",II .. The lulHt i, , plecl pi 1 ~ In. borelt.el I .. h.ull pipt .• bout 18 gauge For hllling will> a"ngle ptOPDne bu ...... il should not be tnOfl Ih,n 8 in. long p.herwI.. IhI MI1'ng w~1 no. be unik>omemltGa Il>e,mocouple (or evln 11 comme,cill onll Cln be InuneII1I. 01 eou .... The bu, ..., uMd " • Sieve" No.2952 whiCh I. f.lh" '00 t"e-_but can be th,ol 'Ie
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In the pllotOg'iph. Fig. 51. you eln HI Ihft Ihe bu, ... , i, di'ected between two broken hllf-b'iCkS on Ihe left-hand side. but I t I ,ull I u!lt • lull b,lck wilh • "mOUH', hple" CUI in ,he bollom Hpt lines ase.ptlro", I gap be""'e'n lhe top briek.nd Ih;$ Itor" one - a """ce of lbout 1 in. I, IUfflclen!. Thisli,,!e lu.nlee he". up In aboul 5 m..... Tu and is I1DI •• upensive In ga' .s lhe burne, SIl, might 1U~5I Once the bricks red ho, lhe g.. Cln be Tu,ned down consid".bIy The" " no ' ..son why such • l.. mKl should not be Mao. pe.manent. wilh lhe bncks cem""e
'f'
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is ne&ded. I hive uMd a I·pint pa.affln Mm. wav. Iwl Ihil blowlamp in needed twiu ,. long to get UP to temper.lu" It would h..... Men ben ••. too. h&d III tile brick, been 01 the FO$Mlcil type 8uI 11 did the work fllquirlld It 'fOUnd loo·C. Naturllly. a ..... I!.. dl.mal .. tuDe Cln be uNd. bul lilt is II III Iongef than 11>1 6 In. !Ibout 4+ In. "1\0. length'" I'OU m..,. need two om,lie< Iw ........ Of kHp rTIOIting the larver ON lrom sit:Ie 10 ~. I ~ been muning lor • Ior>g urn. 10 devise • hw>-Ih~ heed lot the bu ...... ralhe< b1c. thole used on paint_,"ippi"" IOfc/le1l. bul " - not Md the time I Such a heed would distribute the "'" Iidew.VS much bett.. Furnace con"oI would be aa,., ... lOO. In Ihit connection. you mUlt not be temptlld 10 hurry thingl up b\r hullng 11>1 tube direc:tlv, /or 11 will only grow cold 19Iin. Onc. the llrebtlck it ho, il it only • CIM 01 mi.- edjuI,mentSlo lhe bu ...., 10 li;e.p. sleady lemparliu ... Ind onc. IIle bfich Ire hol .11 over the muffle tube keeps ""'Ity .teady. Electric HMtlng . This it fll"" a ..", lor Ihe home c;onSlf\lC101, but ,''' lumlCl will he ml,hdly ,Iow ., In ,eachi"g Ih. oper"'nll temp .. atur •. You will appreciate Ihal • bu'ta. luch ., Ih.I lUll menlloned has • ma~lmum OUIOUt 01 SOII'IlIhing Ilk. 18 kW. end In .Ieclrk eleme nl ollhal c.PKlty would .,.,1" yOU' power suppli., sornewhlll On thl olhe, lIand .•lecl"" hel ting i, cllln, lifenl. Ind • ...,. 10 conlrol ~ .ulomllicl11y il """ be. There 11 little 'illk lrom fi,e. The one Ihlng Iluot mU$1 be bomI In mind. ho'"" ...... , I, rr... you ,rl delllng with Ieth.1 ~ t""" .00 nw" pev •• ally 11",,1 .nlnlion 10 Sltlety ",," IS _illS TO ,hi I,E E. lioM. All mallol partl mu.t De .. rthoed. ........ ' insulltion m,,"';1oI1 Ipplled .nd ",le No. 1 - the 'tJPPIv should ALWAYS be switched off when cn.rlling or dlschrlling
''9U'''-
"
tt.. work. Th. mlle,ial from which wirewor.<. A minimum 01 3 In. 01 good heel insuI.'ton ;., requlflld. otherwise IhI """ Iou to lhe call will prevenl tlte lu.n.c. hom , •• chinll iu p.oPet temp&r.ru,. - lhe "lImenl r.ting il only lbout 2 KW. The ouler r;:e .. il..11 is - or w .. - ...... ,Iy 5yn
I w; •• of IOOO·C_ 'h
+
Elamen ' Fu, ..ac;a Kil . Fig. 52 of • lu,nac. deslllned by Electrollel' Ltd. t"""ralmood,
,.:,;,~:;_ lEE tpeeillc,lly 10' home con-
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(Th. photO wlS "ken. by the
lhe .... mlll ea"h&d gua,d ." :' " OIIe' tll. 1•• mi"al,l, It can ,lther as In 8 KW Un;1 tlted .1 o. wirh 1 4 KW loadlnll for Th. 11111' I, .,..oblbly &dOQuall modll ""lIin"rlng pu.PO ..... The .1.manl1 In tlli, cn. ,r, Silicon rodt. the endl 01 wh,ch can boo the pholO•• 00 IheIIlre HI In thl
~
~::;:;';':'~.Ch.mbe'. HellO"" is to enllllly bul I wor.
dolwl"" ""pplled b\r K.nth.,. bul !hi cn.mber tNrM it. $pI!Cill re" .ctory pIa' e which will "and ..-e wear end te .. th.n w~1 the surf.ce of lhe brick ... f ig 53 shows MClion.I ... iIw$ of the lumllCfl-lhe "'I It. of course. determined by , ... number 01 el.menls used, The.mo.tll conlrol I, ..... ll.ble. but ,arlle. expen.i ..... '!Id I limple en",1I'f controtl.r il ."lly quite ,dequ.II. A thermocouple' pytOtTlet •• I. an _nti.1 il lhe besl is 10 be \101 OUI of tile OQulpment. lhil. onc. built uP. Is e professional fu m~ce Wilhoul the normal CI,ing and hinged O. Ililli"lI door. Ind Ih. chamber size is mo,e rhan adequate 10' mosl rnodel,ngineers. Electric Tube Fu.n&el. Over Ihe years • number 01 homa-mld. electric tube fumlC.. ha ... e been described. using omin.,.,. eleCI"" fire elements lOO home fi •.., c ..amic tubes. The,e Ife sewn.1 hi
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bliaters and Spalli"ll. Third. such 8 tube ;$ usually very /ragile. and it c8nnol be strengthened bV mou lding if ",und •• teel rube lIS some makers hava $uggured: me e>pe, ' men ' , and feee one or Iwo failures wirh e"uanimltV. Fig. 54 shows Ihe stage. in m" ~ ing rhe tube. The "mould"' is 8 piec. of ......1 tube 01 the desired inlem" dlamele •. furnished wnh two lhlckneu weshe,s. W ..ed paper is wO
rou n~
Ihe tube - lh.ee leVers - and l~ Imdpl.,U Or Spacer• • re greased. Th flre.:emall! I.hal _n is "I(os") Is "'3<1 1010 "wmms" 01 'hlcknes~ JUS! over I,." rh .. desi.ed thickness 01 rhe tube. ITh"
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should not be mo.e lhan i In. and 3/16 Is These wo,ms ",e then wound Ihe pape' line. and well toge'he" The li'SI laye, is dry. and then a second laid Ih is one being smOOlhed and down using the two end washers . This 100. is i lor seve,.1 hOt which Ihe
:::~~;.;:~;;~:.2:,;~:;'f:; blowlamp l, ,, ,to fi,e Ihe pape.,
I on no accounl must the fi ,,,,,elube bI! m~de real~ hot at Ihis Wilh Ihe steel lube extraCled the musl be further "i,-drled. and Ihe 'lhiSI&SII Ihe beue. ~ UP to a week. musl Ihen be "fl,ed" IfId Ihis process t 81so be very slow [The p.oblem is moiSlure in the i",,,rior mav form lift Ihe suriace). Fire inside wi, h a Ihe I
You will need tWO alaments. from tha loul electric s.hop. of 1 KW rating. Carefullv unwind O<1e bV th.eading a length 013/16 in. rod through "fId pulling oft the wi.e. Avoid kinks. Mu.u.e the length. •fId then wind 0<1 to " bobbin. Unwifld part of . he SE'Cond element. ar'ld cut oft Ot1e fifth of ils length. Double this and twist. to make a twin wire. This wllf then be cut in two to form the connecting wires. 8f1d 81so serves 10 r.. due," Ihe applied voltage 10 the aClual ..... ting element. You will need two sman connectOrS mede by drilling i In. sleel roo t in. and tapping for two small set-screws;
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,,,
,
,e-wind wilh I fiM' Illlch. II llIe wi". !>,,!! do.. nOI . . . ch Ihl end . usa YO,' Judgmenl .. '0 w","lt- to to.,..". , st>o., unhelted P¥1 01 1Il10 lube or 10 coa •.." the pilch. ThIs ~f\ of 1Il10 job take. ~'''r ~111. timl. ""'\I 56 o.how$the wound l ube The winding mu.. now be COV1tf1Id W "~ • Ye<"f' Ulin layer of _ n l - .he ... IIhouId lull Ihow This. once sel. WIQ 10<, I binding 10 "'.~.nl Idj. c.nl Cc louching when 1Il10 wi,. ",pands .... . Il1011. BeIo.. go;ng .ny fuf\he1. list t~. '''lngetn..,l. An.ch 1Il10 two twIn I~ IIOIllga lengtla. one .edI end .nd • pileI 01 mains cabl. '0 these Wllh II>to f>OmIel twin pore .... in jolnte,. Make su" tIIIt Iller. la no rislc 01 any PiOn of I"" bII., w"l touching .nything. • nd sel ell on • pieca 01 firebrick. Use • I)ILI\I wi.h 13 .mp fulll Ind swllch on. DONT TOU CH ANYTHING. Afl ••• sl>on while lhe lube IIhouId 111<1'0 g" hot . end \'Ou musl nole thl fin.1 tem""fllu". If Ihi' i. no bene' Ih.n bI.ck. pull oul thll plug. Cui 81>0<11 onto tifth ot! each 01 th. twisted el'd lenglhs al'd Iry ag.ln_ 11 i. 11"11 10 dull .~eed • . ,nd Ih,..., make up • c"sing ollnsul'ting brick.! carved out. feedi"ll ,he W"" OUIW''''" belween twO bricks. Mak p • terminal bIocI< t in. Synd,nvo end fill Ihit 10 one 01 the bricllll mull be earthed. '5 m U$! m. PlOIKlive W/et .,.....,. ItIe lerminals if 01 ....111). How you '
d_,
the Sl ......rd br."", connKlors will nol do. U the lempt'fltU'1 illOO high Mlk. two woodftn plugs to li\ "'~ the ~mlm Iube. onto wllh. clnu,-hoIe in it. Wind iron wi .. ,ound . .cll .nd ollh, tube. allo<.n i in. I,om tl>to end . • nd Iwi" liglltlV: llIelll ... Ill' Incho< painlslor Ih. ends of lhe .1....."1. Thil will be WOUnd on uling th.ll1h •. F,om II>to known I.ngth 01 th •• Iem'''t and Ihe dlemeta, of Ih. lube vou C. n calculale the number of tu", ... Sel.CI .n easy se'iW-CUlling phch wlliclI will pe.mh IlIis number 01 tUff" on the bobbin _ .IoOmelhing betw.en 1 2 ,nd 1 4 IpO will probabIV SINe. Set I Piecl of wood in t ... looIhokIe-r with, nolch 10 guide Ih. wire (Fig. S51 .nd .lI.ch <:>ne .nd 01 the alement 10 lhe 1Ii1l1ock IInd 'nc/1oo< . le ..... ing aboul Ih'" Incke. K"" I fa .. lension on lke wl .. Ind wi'" lhe little Nnning .1 lbou. 50 rpm. wind on IIIe wi.e. A. lke Ott- 1Ind. Inc/1oo< lhe wi .. . i n. Not.: It vou 11,,,. more Ihln • fool .. ft _ bulle.. Ihln. yard. don'l wony. bul It there la mo
I.".
00
I'
"om
(KAOWOOl HIGH DUTy)
TUBE 6!1......, BORE x !I"..".,. TH ICIt l£HGTH TO SUIT
..,.... ,"""'-'
,- 2.1/2J
9 0E .HGH AlUMINA
KANTHAl ~' orl)SD' OR SIM ILAR
TO SUIT SAY 14'
L
l'x6 STEEL SE L F' TAPPERS AT 2"PlTCH
'f> 0 ..
EARTHEO COVER
SYNDANYO OR O>.LCIUM SILICATE
".
l/4'mr.All ROUND
'I' F• . M
~" "''' .
INSUlATIO N BRICKS CUT TO F'IT
I-
_ _ .. ' .. 5'1Hr ~ _''~ _
Insul-,Ing brick III round. Any g' PS Cln be ~i;;:; wilh gfOUnd-ull fflgments. ClaM Ihe oIlhe lube with. brick IlIL1\1. and (10< I1 i. worthl 1u51 1.ln • firebrick ' .~'''' Ihl 0.","' IInd to act" . " cIoot" give !heM \rnIUUCllons ··withoul _
_
'' _ _ _
monthS 01 SlfYicl . anod oe>
de,'
0,
::.::.:.='"--'',.....
f ie·" ,'4'1, ._ _ _ ""_. _ _
3. in. bot, MOfg.n 90E H'9h Alu m •• wound whh • klll element for 240 voIlS. 11 buying 11 wound ,ubi '1 is imp<>< lint to lPItCi/y the _ , Inpul - 2 t 10 2 t kW in the .pPlied vollage."'" Ihl opef.,lng lempetllu,," of lhe ce •• "'. lube. This will be higher then ,h" in I~e Nl\ POI 11. .11 .... thll • Helch 01 I~ 1.. lngemenl, ar. copy 01 Fig. 58, sho .. " be senl wllh Ihe enquiry. The oul., caSing I. of tin. Synd,nvo. though lodey Orn! 01 Ihe Calcium SlIical, ... bl, ifUle5 I,om C.pe Inl .. laUon Lld would be ut«!. Th~ Immedlll. inaull1lon m"eti,1 .ound r... alemenl 11 " T'ilon·· KaowooI CI'am" fibre. aupplled by Marg.n C.ramic fib .... lid. 8romborough. Wl"1I1 L62 3PH. n.. sllndard g.edto 11 good lot 12SO·C, bul 1"9II"'lhe ·'High OUly" ",Id 11 1400' C This il IMcklger:I 1n10 lhe _ belwHn the ele""nl ilsell ,nd lhe he" insul.t">g brIcIo.. - which "e cui toughly 10 .t>oul 1 InI;h ~ belwean Ihei. surfa~' .nd Ihl1 01 lhe "emenl. The bonom 01 'h~ lube I1 j)&Cked wilh Ihe wool 'I .... bul Ih,5 mu,l not Ii, lbov1" Inlanded 10< c.rrylng Ihe PO' llound when hol. but "mply 10 make ;1 easte' w lin. A lid 01 some ..." I1 needed, bPlh '"
,"'a eau -
le."
......:I de,.,ing.nd be le.. likely 10 " _ " • 1 the "",•• Iing lempel.,u.e. wl
m.
,"..:t
keep oul din when nol in ~. and 10 _ " ,he POI when ren.e.ing. The" 11 jul' 11 slighl .islt tNI I"" !owe. livers 01 Ulr mltV m.h and e>.PInd be,,,,, cruS! on lOP melll.. end if lhe """ Sl)iill open 1II'dI. lhe I...... could be I SPilling oul of hol liquid. Fig. 60 shows rtwI fu,nlCI wilh the top CO>Ier r.moved. Thil !u,n'ce hll •• ,he. le ... Insulatlofl thin 11 ble. Non. of Ih, dlment-ion, is e
I""
pt........
dfI.,••
i
below ,he ~:j~~',;~~j'_1 of 01 ,he I
i
I
I
PO'- bu, I o;Ion·t I 1000 w,u, (1
of lheult winding. mol'en mull eleme .. , of
I
below I
Ih""min,' be " •• Iheed off when ..... nill"llI· lhe world. Thete is no .eel need 10 I I lhe leltds 10.nd !.om lhe he.I;ng alemenl. Du. lhe fiule cerllmiC beltds """ c:ooIt.. e"culls Ind ele<;ttic fires , .. Itdequ"e The Klual leltds ' " , of lhe heale. w,nding. bu' and 'wlsled. so Ihallhey will nol very hel. The re.minal block 11 of
Syndanyo or C,ldum SilicII". Ihough poreel"n I".mimol block!; som,,'im.. I".ilall/e on lhe "surplus" me"''''- The '''IIul.1Ion of ,he 'umllC" is besr done wilh In "E""'IIY Conlroflet" - • conuol woukl bI very _ ..... Tho.. on el""tic cook.rs w~1 h.ndle 3 kW. I do no. ad¥i .. bullr:ling 11 inlO lhe fu.nece Clsing. ,a I",", conl.oIle.. inc:orporlle' ,,,,,,,,,,, IW'IIdI 10 effecllhe lime-in.eNIIs. ,nd lhe hel1l,om ,he IUlnace would uPIII' lhem " H,.te. B.lck.... A ,el'Iively new developmenl i. in Ihe form 01 , hell Inlull1ing brick with , ""are' elemenl emt>edded in Ihe lace. AI fi'51 sighl Ihese woukl Mem 10 be Ih.lde.' module fOI Ih. ~on.uuc"on of , Ima\l fu.n.~e. There II el ... a vitiation. wi,h Ih' "b'k:~·· in lhe lorm 01. hollow IUt... mekl"lllhe basi' of • Iubl: fumlCe. The •• are 'W'O probIl"'. !he fltsl 11 thll lhe unilS .... wound lot no mora Ih.n 60 IIOIts .... IhlI e;lhe' e helW I.e""orm" 11 needed. Of .,.,. musl u" four unilS. The 5ICOI'\d Is rhll lhe hp, lace 01 lhe bnck!; will nol CI'IY "'V Iced· VOU would need • auppor!ing end 'ne" ,,,n· lIII.enl or e me,,1 lube If lIS;ng lhe lubul" type. BOlh ,nd lube W'Ould hlVI ,0 be 01 hUI resiSling steel Of of conJ.iderable IhicknHS if any .e"on.bl,
,r"
'''''''''o5''''C:
"00<.
"001'
00
life w .. 10 be eJlp..:I~. Howev8f. Ihe5ft ... nol difficult problem. 10 gel ~ end .ude.. who a.e Inll'"led in Ihis ...... loptT-.nl should wrlle 10 Mesus W,J fu ... , Co., Lld, W~lord Road, HOI lingh.m NG2 1£8 The bricb , .. known as 'WII_ Cer,mi, fibf. H."...-RaIitUnc:e Wi.a. This i. obllin.ble from Ihe !(anlh.1 Ilrm al •• ~ raI"'ed 10. from London EI"I.i<: Wlra , Sm'th. Co. (LEWCOSl Church Road. London ElO. as _11 .. olher m.nulaclur.,.... and ,n small Qu,nlili •• I,om K.R. WIIiston. New Mills.
I _04_ 10 W"
SIOCkPO
•
• •••
I
,elist,nCI needfKj to limit the c","nl to lhe desired ~r - If!. 101 1 KW" 24011 t......",t.nc;, at Ih. wooing lempe,"ufl mull be auch I t to limit I"" 'u'reIlt 10 10001210 • 4'7 .mp. SII\' S8 oIIm ... Nut. lha ",rface aI. . of lhe wife m ...1 be """ thl! it Cln dissipeu, this powIf, A no! untvtIiCIl IIting is a.s wllt&iSQ Inch of ",rf_ ..... So Iong.s lhe le<>glh 01 wife naadad 10< this crite.ion I, Jeon Ih.n Ihll needed to provide the reQuired ohmic fulsllflCil lhe elemen' will be ""le. bill I1 1111 opposite condition Itolds. then it will probably bu.n ou'. finally. Ihe'" mull be enough room to wind this calcuID ,e<> table show. how 101.1' gauges 01 wI.. ....... bean I_Mad to ITIMI lhe .equired crill.i. 10< • 1 KW 240 OIOIt hell" elemenl. HOII thl1 theM 1Igu
OI.IIPIlI I1 wound to • resiSl,nea 01 157.6 ohm. The 19 gtug
,.et
va,.,.
Wind,ng Length lInglh Reqd FI Turm OIl i",he$. 4 in dia For- Power f Ol Retisllnce H 622 82,9 99.3 OS 110.3 2. '2' Th,. IIbl. $howl Ihll I"" 20 1JI"9' co.t 01 m" ..;.I. tor , ho ...... m. . . .11,,, wl" rlQUlr .. I 11'''''' lenglh 10 diulps .. The li"lI g.n-fl
G."" "" "
'" '" ''''
'" '" "
,.
""
.M
CHAPTER 10
Safety Precautions
Sale'v irl llIe WOtkshop 1•. mosl 01 Ihe lime, no more Ihlll'l "applied common sen..". ,rid ,,,.. Ih'l m.n¥ oflhe Parlia· menl.'V El\IClm8ft" on tile IlUbiecl """'" 10 _me Ih.1 mQll people wor1II' ga.·hose In MWf'!I• . • nd lhough ,lie hose I.llur. v.1ve Id." I .ssu .... Ihal 'j'OOr lIquipm.." hili ontrn will ehUI off lhe ....POIy, ,he ""',,' burst 01 n.m. can _ Iir. 10 01 .... Ihong .. The .-cond hazard is from "'" h. .m", 11..... il..1I The ptKlke of moving IIIe torch . . . 10 Gbse",e ,he m.I.1 i. "o.mal. buI how m.n¥ practitione.. Ihink on ., 10 ...... re lhe na .... it. now pain'ingll h.v. mvs
'f'
Th • • nSWIf '0 lhese i. twolold Firs' Ih. helt IrU,m.nl tpOt It>ould be a. li.ep.ool • • possible. 11 worki"ll on bench, then llIe lOP be covered with two ,..,.•• 01 bricks, woth lJIaggere
,"""Id
"""t
" inl"'il ,1'1 inch or S<) of DRY "nd. Thl. w ill Cllch any d.OlIPings H f,ly, and horn It • QUiclr IhoIfIlful of send can coollin • om.lI fi.. whilsl ... Ching fo' th, IXtinguId med. from. clelln hllndkerch;ef (NOT IInl) 'rId looM b.rldll/l will keep lhe I,sion ct. .n on IhI w .... 10 "Cn",'IV" a1 ,he IoeII hospil.t, Oon'l neglect .his _ . bum to p.ompd., by e~n. wijl g ..... bllle lrouble, but leave il liD """I d ..... rId vou mlY well be in ,rouble, For minor bu'AS. Ihln .cri~ne basad bum dressings eln t.., usect but ""8ft ...... MIIr 1he ar:Ivic. 01 yGUf doclor if if> doub •. KHP Ih, .. d ....ingl in the worhhop o. .... rby, bu l don", !orga. - ,I is ,he din .ound lhe bum wh,eh will cauSl infection, s < ) ' " thll you. p.eWI are clean, Clolhing. Whit i. up muSl cOme dow". arid vou. lell "I vulne.able, C"pet sliP\lflrl "e nol Ih. belt things to WUf wilh mll,l 11 800"C I coupl, of 1. ., higher up W... 1,.Iher $!>oM. Catlon twill GVef,III ,r, ..I. _ or as ..,, .. Cl" be - bul lhoIe 01 .... n·m_ libfa e,n ~II"'1y mell 11 _heale
""nded
I""
jumping 011 a 1001 in the qu,nch .nd bdglng down apert neck 01 I "',n t The u.. 01 gloves is debalable. 11 , ..... land 10 mlh 'j'OO clumsy and " " " - "'" 11... 01 droppi"'il ~ .hen partI_ t..,nlf 10 do withoul,"'m, 8uI rf 'j'OO haYI • pa.if 01 flDlOnlbl¥ MJppie chrome ,..,"" _ , iheH IhouId be worn ......n wortung with hol high-'empeflll..-. ..IT (or moI1en lead If you u.. tha". Ther, .11 10.... 10Clllad "hell proor glovel on lhe m"kll . but Ih.., ... nol suitable fOf Ihis clns 01 won _ mlybe" tempering 'empe'''u,,, , bu l they WOO'I STand red·hol m.I." Th, obiecl cl the glINa 1$. 01 course, '0 pr01 workplecesl One Importanl paint _ the gtOVet should be luch Ihll 'j'OO Cl" wl\ip llIem off smlrTly: lhey w,1l keep lhe "''' f.om ,'" hol me,,' from VDU_ paw bul the glovl il lhen hol. and Ih .. hell will travel Ihrough soon ,fterwa.ds. FiN"". we .. I cap OUIf'ICh I 1Ii_ 01 .,eaI Wllh • hoI. in it, and the <>l '0 h.rden. i in, loom 1001. bY ll hll 100115 hOl , Ind vou should," I Slid at the beginning, UN you, common .. n.. Splllh". You mav well have dumped , flw jobo: Into IhI pickle·balh In the 1"$1, 10 you whll hIIPJllnl. 00n'1 leln ov.< lhe QU"""h link, Ind if lhe wor1o Is of any ..... 11 all , wear proper II"9gl p. TheM ar. d,,, Che.P. bul MUST t.., \0 Bn"sh S1Indard 209212 These If' and will nol .nail'" In>m ...., .. gI_ wm, Th.,. hII .... little side--plec.s Ihlt 11011 thi"'" lrom comi"lllhal way. arid can be worn ""'" ~lacIe .. They "S<) h.v. I !illll '·,OP sh,II" which prevln,,"utl lrom 111I1"'iI 11'110 Ih. 8!MCI bl!tw... n ~, IrId
t""
.now
"""proal
Ihe eyes. If you <10 gel 8fl'(lhing in \'
,
required amounl is In Ihe pol. Allow plentv 01 wace Ior Ihe ti(le 10 rise when wor. i$ puT in. In the case of lhe electrically healed high'lemperalure furnace Ih' salt level should be below the UP!ler end 01 the element. The,,, will be no 'rOlhlng on remelting SO long as you have had a lid on SO th81 it cannol absorb any moi$lU'8. and ..... en Ihen i. will be rolatlvely slight. However. il is worth again repeating Ihal Ihe selt may form 8 cru51 . and when re-melted 'he e"pansion of Ihe Ikluld below may cause this to crack and send out a spurt 01 hol salt . So, keep a subs.anlial lid on .he por unlill"" whole is melloo N,ver Slick your head over Ihe top 01 a salt pol in service ... Iway. observe at an Bngle, always wear 852092 grade 2 "" Impact"" IIOIJgles.nd. efl', .nd glolleo il you can po •• ibly manage wilh Ih em All work PUI In.o Iha bath muSt be waler- Bnd oil -free . and should be immersed SlOWlY. Particular care mUSt be laken when oil .... uenchrtd work is to be lempered al above about 220·C. aO any residual oil may "Huh off"" Prlor degrels, 109 i. 'eCOmmended Il lhe tempering balh is above 24S · C. Slighl sur1~ oil con · laminalio n should cau ... no trouble in Ihe Auslenising bath. but if Ihere are any holes in the work;>iece these should be cleered oil belore immersion. No fi",url!$ Of olher d ..... ices for U$e in salt baths should be made from lube G.eal cere should be lahn ID ensure Ihal no foreign malte' lalls inlO Ihe balh . whelher COld or ho~, It is imperative Iha. no waler should f811 Into a salt bSlh_ ~nd waler should nol be used 10 exti nguish anv fire adjacent 10 One. Avoid overhealing any salt bath. They should nol be left "on hllat"" when leaving the workshop lor more than Ihe odd mlnule or two. even il Ihermostatic control il filled. Overhea ling can be
0'
" , and POlassium Nitrale. These can initate Ihe s kin. but 8re classed IS "'non to. iI:". Soap and waler can be used 10 wash off Ihe Skin.• nd an eyewash solution if sny powdel gelS in Ihe The sell i00i<5 li ke coIou'ed ~uga,. so it SHOULD BE KEPT AWAY ~ROM but ~ Bny is ta ~ en by mOUlh plenlV of waler 10 d,ink and call Ihe moheo I .I I area w ilh solu tion (b) wash again (c) 0;,,", epply a medicaled see Ihe doclor or _ .he pa.ien. 10 .he sail is nol inflammable In ilself. but slrong &UppOrtM of combustiOn' wood clolh contaminaled wilh the salt witl vigorously. Some organic com.esct vigorously wilh the sah healed. Cafe should be laken Ihal ~il18ges 01 powder on wood cleaned up promplly be washed . NOT dry_ . as is 8 'UCtion with drysol~tlons.
above
01
"""" , " .0,
r8{Juires med ical
The salt is supplied in plaslic sacks, and be lad led from Ihese inlO !he POt 8 metal spoon 01 ladle. Slorage conshould be moi$lu,e-prool: I keep plastic bags inside large Ne&cafa U$Ml sah can be dispo5lld of by
washing down Ihe .ink with, good HOOd 01 wale •. Within Ihe temperalu.... range and quantities used by model 'ngi"",, thi' $811 can be regarded as non-hB.a
,
•
Is Ihe orde, of Ihe dey. S IOfage and dispoul condlTloM .'" \he M me IS fOf Te"._ t"\IINIT. Elec1ri.,.t. ~lec:tricaJ h..1Itk in Ihehelt· .... the A"'" as t•.,tmenl ahop 1'1 _ I t - I'M,,, tw
quendJing I.... PIt.t .... will bum Itwouvh InI
''9''.,...., ••
whk:l\ m ull bI .."heel. Fuail'l\ll i$ beSI doni I1 lhe 3 -p1n pl U\lI.IOQ, b ..1 if 'u~ " ..... he .. tor If cif1:uft tw .. k. . . .'e fille(! to t"- conlrol bo"J IheM must be 8n""ge
Conclulion. 1""- cI'eful p,actitioner w" m"1 fe w dlf'l\llll'l in heal I,,,"ment. b u ' no .mount 01 " prec.utions· will sa .... ,n. ca,..... from inlury. Heat treaU'nem prKlice 11 probablv Ieu dlnge
APPENDIX 1
Thermocouples and Pyrometers It i. POnlbl. 10 <>blain me,cury·ln-9lln th.'momll.... w hich will safely ''IIis,., "P 10 360-C Quite cheaply. and nitfO\lliln filled me.c .. ry tlle.rnomel~ in splCl'l glu, c.n be had which ,ead 10 6OQ- c, They ......,he. "191., bul can bI used lot IIrnper1ng - lhough 1 make • .,HI PI'OIt'Ctil'l\ll illlellh lot mine. Thl WIll· known "ROIO lh •• m" lemp... tu •• indi<:atorl, bIIed on I bi-melallic coil, can be boughl to .. MI "P 10 300· C hilly , •• used I t OVln Ihenno"""lrs)lnd Ife more robult The m.f1:ury.in'$t"1 di,l .11,,· mom ...... w ill ope'l.e saflly up 10 6SO" C, bUI IhlY Ifl bolh expensivI .nd b\>1~.,.. None Of these, how_ •. win "'...... I", 1Imper"UII Indlcalion wllen hea.in\ll (A"'.lnl"II\II) I", quen<:h ha rtlenil'l\ll. Th. 11I, .." o-.la<:tric pyrometlr i. the onty pra<:Tlc.ble ....w .., 15' sI>ow. \he prino;ipfe. If \h. ;;;;: belwee" lhe lwo wires., . A~ is ; .nd I"-t 11 ~ 8 ~ i. k ~t coot, llIen i. .he .....1•• "M~ WIW show tlllt. volt. dlv.lop.d which dlPendl on Ih. t differencl 11 lhe TWO juncthal il Is lhe t .... PIt.IUll OIFFE RENCE wIIi<:h ; If the mel .. 700'C, and " S " 11 .1 " "." w ill bI lboul
","
EMF 9&""81111 doos nol vary eu clly with Ih. lempef,tu •• ; plOtl 'r'I\lI EMF l\I&in.l IImpe<'llu" dIHe,,,,,,,e show! • ,tighl cu"'e 10 lha \II.;oplL This mean. Ih" tile lrue tlmp.."ure mey nol be ..Icily Ihlt lound by Iddi"ll me hol ,nd cold J.. nctlon l.mPlt.t ...... WI will deal wnh Ih .. probl .... lale,. bul il is not ":ioul for 1Ie.1 ""tment Pown In Fig. 62 'A" Il lhe hol junction ,nd BB lhe wtres within lhe immersotd le"\lllll Ihe m.,,,i,I, blll'l\lI tile " tl!e,moelactric" alloy. CC .re connecTlr'l\ll w i.n lelllil'l\llto 11'1' mll., " M" Ind " Rn II • H,i" , ••1.1.",,1. 1I CC are plaIn cpppe, con d .. ctors, Ihen Ihe effective cold JunClion will be I1 DO. This may be clOH 10 Ihl lu,n'CI. Ind 00 CO\>Id be Quite hol. 1""e ffective cold Jut'>Ction can bI .nov.d 10 Ihe m.'I< .ltlle, by usil'l\ll ~.I .1Ioy _ifI\lI c.tlllllcalled I .. compensati"ll IeMl") CIf more limply by conl,nuing Ihe llIermocoupll ellment from ". tighl througl'110 M ,nd R, This is the mllhod I UH, lhe ""', ... need not be .11 1"'1 I. from lhe fumace. •nd one h.. 10 buy • Ylld or SO of tt.ermocouple wire .nyw • .,.. The /un<:tion of lhe ,eallllnee .'1'1 " 11 to .111""" Ihl effect. pi ch.f'l\lIcc .. '
.we
aw.,.
'"
f ", I' ' ............. ',.."4"'
.· ' "
B.
A.
:::.,~.~::-.', """......""../ __.JB".___--,,,.____-'C;.~____ ~M~.; A.
M. as the cOIJple elemenl yetS ho•. If the feslstance of 88 and CC were, SIIy 0.5 ohm and thal of the meter 1 5 ohm. then anv ~hanga In the former would be app'eciable, 8y in .....,ing this "ballast resistance" say 100 ohm, then the changa in re.iManco o f AA and CC wi th temperatu.e will have n8{fligible elleel, It saN8\I ~ fUMha. pu'pose, too. II Can be used to ma tch the Indica lor to the pa.ticul~r thermocoupte used. We ,hall make use of thiS whe" "adspting" lnsttum~nts for home-made indicato.s.
alloy •. notably those ~sed OIl Platin um, but none likely to be of inte,ost to us. Atl these thermocouple alloys a'8 now made to ~ 8.ilish Standard Specifica,lon, and the following table, ta ken from "The Model Enginee, s Handbook'" shows the EMF developed in millivolts wh an Ihe cold junctiOll "ands at O· C. This assumes that the wire is to the releyant 8.5. . but Ih e diffe rence between this and others (8{f. to OIN Sld) is neg ligible The EMF in MilliolOlrs de""loped bv couples isgiven in the table,
THERMOCOUPLES
A=Coppar-Con$lMtan III 851828 9~ lton-CI!nstentan to BSI 829 C~NiCh,ome_N
A number of differant Blloys a,o used for the thormocouple element!. The cheapest is coppe' ag~lfI5l "Constantan" 160% Cosloer 40% Nic~el) but this ~an ope.ate safely only up to about 500·C. Chrome!Eureka (90% N! 10% Cr vS 40% N! 60% CuI Csn be wOfked inle,mit\en"~ up to 850·C. or 100°C conlinuOlJsI-i . and has Ihe merit .hat it delivers the highest EMF/ ·C of any. lro,,-Con$!&ntan is the ne_t besl in thl' .espect, and Can work continuously~. 150·C and intermil1ently up to IOCO·C. 11 is cheap, and well suited to ou' wo,k, provided you ,ocalibra'e ir 1t i. uslld fOr long pe,;oos Ida~) above about 800~C. The commonest for highlemperBtu.e work is Ch'ome!-Alumel 190% Ni 10% Cr vs 94% Ni, 2% AI + Si and Mn) which can work al! dlY St I 200 ·C. It does nOt d8\/elop Quite su~h a high EMF 81 the Pfovious types. but suIfi~i8nt klr OUr putp<>se. There DU' mhef
,,
r>, "
A
," , ,,' """ ", ,<, '"
..
'""'" '" 300 350 400 500
6·63
'"
liS," 11 .88 .
("1'" 11· 59 "l~ 20·59
1 6 (" 26·10
600 /of' 100 ("C" 800 ,
""" """
2 ·02
, ,
, ,
258 5·27 8·01 10· 78 13·56
2·02
1O· I 6
16·33 19·09 21.8S 27·39
12·2 I 14,29 1640 20·65
33·11 39·15 45·53
2491 29 ·14 33.30
'''' 6.1 3 ,n
'"
41 ,3 4 8·9 55·9
B.
Now, let uS suppo .... Ihal we are using en Iron·Constanlan coupla with Ihe I>ot junc,;on at100·C end the cold 811OO·C. The indicatlld voIl&oe will be 39. 15 5·21 n 33,88 mY. This correSpOnds 10 a · temperature of 613 · C. Add on the cold junclion tempera ture and we find the sum to be 1 13·C - 13·C rugher than it actually is. So, the cold junclion must, first, be kept as cool B. possible (in reallv accu,ate work it i, set in ite In B thermos "ask) and sarond, we should keep a thermome t er nurbv .0 check the 'empere,ufe. If the cold junction is k9!l' within +/_ 2 · C of IS"C. the ~ffOf will net exe&ed two Or Ihree degrees if the cold juno: t>on temper.tufe is simply ~ddlld to Ihet indicatlld on the mete'. If Ihe meter end Ihermocouple .re CALl8RATEO with the cold junction e< 1 S·C the etfOr will be neglig ible. The con,(fuction of the thermOCOtlple is simplicity It ••lif. It can. indeed, work Quite satisfactorily if the wifes are lightly twlsled tDgethef, ThiS .... ill read cO ... II<:lly, nu, the'e will be a tlrne-Iag between
-,_ ._ --' _,-
"
c.
R.
.eeching the tempera ture and that indicatlld. The ends cln easily be wefdlld together if you h~v. I !ittle Microfllme o>cy-butlne ,... ch .... indeed. any welding eQuipment. The ga"!J" of wire is unimPOrtam except as regards COSt, and 26 gauge Is Quite S8li$l~ctorv, lhough I would Jlfe/er to .... e this in a proleclive shealh, That seen in Fig. 63 is 18 gauge, and Ihls can be used in a lurnace or .ven a salt POI wllh 110 sheath, lhough or>e Is preferable In the IlIler ca ..... Twin Ihermocouple pairs, aboul 30 g~uge, insulatlld wilh fine heat-resitlsnl sle""ing, are 1IV8ilable. For the knockabout work of heal tfurmen. I would tend to favour the 18 gl U{le wife, bul il IS 001'1 a IIueSliOll of fragility; Ihere is no differance in the effecliveness. The couple wires mu". of COUr!l{l, be insulated behind Ihe 8<:lual lunCtlon, end eilher $Ongle or twin bore ceramic or silica in..,lators can be had for thiS pu,P0S8 from Scienliflc in."umen! supplier., (Gfiffi" & Georg.e. Gallenkamp etc) Of ffom Mo'g'" RefraCIOries, already ment;oned in connll<:lion wilh muffle •.
f". ",...,,'" .... rho """"" ..... . "'.
_
U
,... •• " '~ ._
IIfO,C_ _ _ " ' -
_+oR' V .... _ _ .,_
,
mu. I" seen In "'ov, 6J. The.. In lurn. be prOleclad by "'lIing the wnola Inside. ""al sn ... ll>. The end etn be cl.:oad eillMo. by folding O\Ie. M>d I>lm_ lMI'ing. '1' _Iding In , plug ,..... ""-Ill> should be I fal"" cion fil on 1"inwll lOB. Thi' will prolecl Ine coupl. f.om knock • • • nd llso (In 11>, c.... o' Ih, Nil poll from • ge ..... will ell''' I I,ma-tag in 11>. ifldicalionl I'0Il' Indicato. wHl land 10 ",ad the l"ml1l" lu •••, It was J ow heavy lube it. There ;" no need. 10< our 1)1.1'1>11181. 10 II,inl..a 11...1. Once ele'r of lhe 8etuII'um.,,, tl>' wir.. mly be in,ul"ad wltl> ordinaoy 1l_lng. er , •• likely 10 11"1 hol. Such 11""inll etn b" ob.. ,ned lor otdefed) 1h...... 1l1> radio ... rvice .hops. Th. Indicato, . Th. maximum .".ding "ling Jron..conlt,n"n wdl be abou t 50 milll"oI". and lor 8$1827 Nie.- NiAl, ,boul JS mY. 11 I'0Il ha", a "multimll'''' will> I milliVOIt 1C,le. wall and 1I00'I. YOU C.n tl>il. Olh" rwi ... YOU muSt eilh •• Som, 01 m~,
I'"
1'"
1'''
or mike 0/11. T""I was a "m. when .....rpI"'. micro-......... ten; Wl<. ,eldlly ''''iI6bll. Ind the. . .,. o' eJ
ag''''.
'"
,r,
that it it ot"-I... end ....."ncea 01 ..ound 750 ohm ,,, common. Le. 1'1 IlUPPO" It is Il>own as 7JS ohm. This Is whe" tha ."si'"nea "R" of Fig. 62 comes in. 11 _ "",k. this lCXlO - 7J5 .. 265 ohm. lhen w....... a total .. listll<'lCe o. ICXlO. ,nd the w;Urald di'Kt. Sucll • ,..lllane" would be "built up·' willl one at 200. _ It 50.•nd one It 15 oIIm ' egain. from the ,Idio seMc. sI\ocl. ··High SI.bln", I" ToIer.nea- tn:Ht, Howeve •. sUppPle tll. ml t, . hIS • .... Is"nc. HIG HER then 1000 Ohm. what than1' h....... one har • . 0-100 JiA. 1250 ohm. Apply Ot",,.. law e · E1R. . m,," 'O$isl.nce ia ",,\ as !lh.... all I" made 10 .. 100.,a __ 1 Ind .. fIe, • pe,iod. In u ... 'IIerI 11<15 been I tt>enga in the cll.."'''ri$lCl of tile coupola llemenls. The Iowl< and ia done at I 00" c. The lher mocouple is $It In Ih' " •• m above NOT In tile Wal". Ilself boiling s... "''11 65, llIougI'Ilt UfO be done in In etKUjc; ke,tlfI JU61 IS .asily Ma~" ... " tIIlt Ih. cold junetion li.a. Ilia m"tll. if usad u In Fig , 62) I. It 15°e. le' th e Junction .elk kM ebout len minutes and obse",. t.....ading. let it cool 1 linte. and ,_.,. 00 mi!l th, . . times and like Ilia me.n. For In inlermediate tamperll"" you Ctln. 11 you hi"" IImpetlng ul. bll h
m""
"_ .... '1 '~. "w,.,,· ••• .,.Q-'_. 0'0'"hLd ••• _';"..•.
-
0 - '''''''''
"
... _
.....
e
"''''5\.nce
""ed
THERMOCOUPLE
w"", _
••
"
• •
.
• • ••
•
•
'"
,hera will be an arre.' In ,he INCA EASE in 'empera,ure. Aepea, 'his a coup1e 01 ,ime •• always removing any .cum which forms on ,Mo surface of ,ho metal. The mean of the ."e$l pointS is lhe actual melling poinl 01 'he me,al. You can do another" aOI·C. with pure $81!. Note. NOT ,he I>ou&el>old variatY. Ask 81 ,he chemls,s lor ··Sodium Chloride BPC·· ,hi, is commoo salt. bu, chemically JlUte. Once 811 ,his h&5 been dona \'Ou can ei,her make up • table or mah a I$W .cale ou t 01 paper ' 0 6,k:k on 'he di'l. I use a labia. as I hltVe O1her uses for micro• mme' .... and don·, wan, 10 ,ie any of Ihem up on one iob.
The linal alternative is e-pensi"e. but definitely ··io ' he mood··. You can buy (or oome 01 you may be abl. to make. for all I know) a oolid Slala digi'allf\dica'or. which will read OUt Ihe ,emp.lfatu,. on lighr . emiuing diodes. 11 you ha"e ...."e.a l the._ mocouplft$. high tempera , ures end low yOU tan build in 10 Ihil 8 correcting ci,cui, which will allow fo' ,he use of coppe.· constantan "one end 01 the temperature range and Platinum Aho(Iio-pla'inum at 'he olher:. univ&ff.81 !lVrome,., IndicalO' Thi. i. nol a booI< on electronics" 50 rh811 mUSt leave Ihe delail for you 10 tort oul Sufficien, for mosl of 'he eleclronical .... minded 10 know Iha. it can be done I
APPENDIX2
Carbon Steel Cutting Tools Many reade,s may neve, have made a Culling 1001 in their livei. apart from 'he oOd O-bil. 800 would 'egard anylhing .... cept high_spell'd steel (Of e\litn tungSlen carbida) ss being (I very inferior 1001 iOOeed. This is a miSlaka. The ONLY re.son for using HSS is Ihal it can operale ar 8 highe, tempe,atu,e. and can . 'herefore, cut FASTEI'I. HSS is much mo,e oxpensive: ;1 Is not ~s hard a5 prOPflrly I,urll'd carbon looI- lleal; at ,he prOPflr CUlling speed carbon 51 ...., has B longe, 1001 lifa, and fo, fini,hing cu's below 80U/ min. lUll much longe' AOO (again. when properly trealed) ca,bon 5teel will give a belter finish. Nor i, it lrue , ha, ··YOU can·, lake heavy cuts··. This is nonsense I have bv me a table of ··speeds and feeds·· for carbon steal 181hetools whit:h listS cuI. up 10 one inch deep el feeds of ona e,ghlh of an inch per re>". Finally, ca,bon steel will lac~la '·the really ha,d stuff·. Until quite recently I1 was used fOf machining ,ha chilled C8St iron foil. used in Sleelworks (Ihe aurfaca deliberalely made as hafd as Ihe hard SPOts you can"' machine On your C8Stinglil and watchma~ers habitually cui hDrdened and lempe,ed sleel pivots wi,h a carbon "eel graver_
The only dil8d'1antage whiCh afflictS rhe matenalls thalli ··tempers·· a\ quire I low figure. HSS 11. inillal ..... SoOfter Ihan carbon .teel. (Fig. 66) but whe'eas Ihe 1811er would Sl8rt to lose some of ils cuning ha,dness about 270 · C al the 1001 point Ihe former can be oper.,1I'd 50 hot thar rhe cUl1ing 011 will smoka and. inde&d. I have .... en SPeCi81 grades ,un for demonstration pUrpOse. cuning al a dull red h08'. The same is I,ue of Tungslen Carbide: its virtue is 1'101 ils har~ness- i. is inlended as 8 FAST CUTTING TOOL perhaps 8"hre. lime. 'he SPeed 01 HSS. This is Iha Crux of 'ha malte,. You can buv a couple of feet of carbon 1001 Sleel fOf IM price of one short HSS loolbit : you can file it. bend It. forge 11, and harden i"o cuI tough allO'( steel. ""en hard cas' iron: and you can gel superb 1001 finish on rhe worIt . aur you MUST keep Ihe CUlling speed down and keep the 1001 point cool. For roughing cuts ' ha speed ","",uld be aboul one Ihird Ihal used for HSS I,hough if Ihe COOlanl supply is good you can rry fasle,) and for normal finishing curs ,he machine should be run at abou "w" ,hirds Ihat used for HSS. In facl. for bfas. '" """-cutting mitd •• eel . laking modftl engineers' finishing cuts. 'hera may be no
8'
'"
"'"
-<. CA''''"
~""
.00.
•%, ••• •V
APPENDIX 3
"",-HIGH JPEE 0 STEEL
"'"
•
>
British Standard Steel Specification Numbers
~
I
"'" "" """'."'"'_<_______' __ 1500
8CXl.
TEMPERATURE _ °C f. j ~
_ _7",,"7 " _ _
:-, , .!. ....:.:':._"""=.::'~~ __ ..
'7 7 .....
nMd 10 redUc. apeed 11 III 11 ~m. of COU''' , ...urning rh" tou ua. Ihe "proper' HSS c,ming iIIl ..ds: m.ny ~ engi,,"", run .1 urbon ",-.I speed. ,lithe time)) ClIrbon steel will CuI Inything 111,1 etn be cui by HSS. • >'Id .... ny ,hi' _ ohen use C'fbidto kII' I.nd donn', chip ., The edOM .itherl but i,
doe. lak, longer eUI will' if; lhe hUlry. cnYWlyl On ltoe o,,"lion of ·'qu"ity 01 finish'-;, i. not .Iw...... pprKiated I"" the ",rt_ of Ihe worII ,ib. on m. wor1<. Carbon It'" h. . . r..- g••in man most HSS, .nd 11 gllln fefiM'd, ......
Prop.tly "'"d.ned, .... d lemJ)ttred only 10 fi r I, 1. esssnli." 11 mOre
ID.
Ilk.. up • Mn .. IInish from the oi ..,.,....., l!>us !JivIng In ...... ben.. 1in0ah 10 ,,,worIt. In ·'O,,..,...nlll TummgH we ....... 10 go IUMl>8r SlIII; we rely enllrely on the
,,.
' .
M c.....
_ _ <_ _ . . . . . . . . . . . . ..
"1001 Iln;!IIl" I", the decoraliv. reflective
SUrflCH whOch Ire 50 much admired. Ind ......., go to lhe ~th 01 lapping lhe culIl"" edge with rouge on In iron liP' Wilh Ihe ever-Increasing COSI 01 ,11 alloy lleelllend HSS in PIM!eular) il does ml~e some sense to reconside, Ihe ollC' 01 Ih, 'oId flllllionl8 worllll. I would not of COO'H. suggest Ih., w. aben!ion HSS wholeHle, Ih., would be foolish But /of It is worth I wilt conclude thiS not, by wl:z,nring Ihll Al l Ihe c •• nkshlft. I have made. end th lt is quill I lot. hive been finished. In(! mo.t of them ,oughed. using clrbon 51"'looIs on the crlnkpins. Ind mosl hive been lurned on lhe ''''1 w IlY IS w"'~ Why nol g;"'" I1
"""at
jou",,"
• Itl,,/
The Old Brit ish SIIndard 97&1955 characII'io.ed by 11>8 "EN" numbers which many of uS 51ili UH. wu ,epllced by Ihe ","w BS970 in 1972, h re.11y is t>mlllh't we stifled 10 uM ,11 It h.. one gore" Idvantage. in thlf the BS numbe, i,sell g;ve. u. ,h. cafbon conlent ' 0' many steel •.
The numbe, COMprises Ih'H dig" •. followed by I !ener. loIlowed by rwo mar. digils. Th. fr"l 'h'" digit. twO purpo.... They lIiye • b,oad Indication 01 11>8 TYPE oI,teel. thus 000 10 199 '" all --pl,in- cerbon .teel With some m.nea""' contenl 200 to 240 "e "F,ee-cuning" "'e",ons 01 the above 300 10 '99 a,e III 'S'linleu" 0' " Hu' Reslsling "eeis 500 10 999 I,e In --Alloy" lleels and wilhin Ih, number Ih. mlin .IIOVir.g ,'emenll cln be Id.nt,fI,d. W . . . . concerned lfor ..... t".,men,! only wlUI the pI.in Clrbon Iteel. .ncI, pemlpl. their I,u cunlng 8QyiVllenl. The first dillll nn be ;gnorad; 0 .nd 1 me8~ "plaln" end 2 m .. n. " frH-CUlI ing". The SKond lWO dlglts. Ipr&ceded by 0 0.- I J g;ve 1"- "'Ing'''"' conlenl myl"plled by lOO; thu. 145 mIIanl 0 .' 5" m.ng ......... If preceded by 2. Ihne digits Indic81e th.
"rv.
sulp/>u, """tenl. &{IlI,n, , 100.22. will be I O,2 ' !!Ii Iulphu, 5t...1 The ..con!! group 01 IWO digi ls Indicl1es ,he c.fbo.-t conllnl multiplied by 100. Th", '5 indicate•• 0, ' 5" ca8g8 I B Ih.tll thould be "",m.,ised It.round 880 °C. The speCifit:lll_ doe. no. COW< 'Tool Steel.", with m",e Ih,n ' " ca,bon.
ba.,.
he., "..
on
APPENOIX4
Approximate Conversion of Hardness Scales (ASTM Conversion Tables) (FOI' Sleels) SHORE No.
VICK ERS
'" '" '" '00
"" ""
1030
'""'86
820 '00
""
SA
82
'""
"'''
'" "" '" '" ,'" '50
"" " '""86
"" '00 ,SO "" '00 ""
82
""
" "
'80
ROC KWElL
"c"
""
1000 lbffSq.in .
""
66.4 65.3 64 .7
"
62 .5 61.6 60.5
52.3 51.1 4 9.1 4 7.7 46 .1
SHORE No
'"" "" " 50
'8
.,"" ,,, "" "" "28
""
59.2 57.8 56.8 55.2 54 ,1
(For Sleels)
"" '" ""
'" '" '" 20"
28" 20"
""
,.28 22 20
"
VICKERS
'''' '"
"" "" '""" ,SO '" '" '" '00 280
'" '50
200 220
,,, "0
"" ,so '50
'" '"
ROC KWELL " C'
"4 3.6
"" ,,,, '"
1000 lbl/Sq.ln ,
'" '"
41 .8 40.2 38.8
"0 "0
36.6 34.9 33.3 31.4 29 .8 21 .1 25_6 22 .2 20.3 15.71958) 13.4193 .4 81 8. 5189 .581 6.0187 .181 0 181.78) 178 .781 171 .281 161.68 )
...
The .... conversions musl be u$OO wilh discre tion . especi8 11v as re gards Ultimate Ten.Ho Snenglh column. TheV re lale onlV 10 C.rbon and low alloy 11HI. and ... clude "Slain le"" s leell.
'" '"'" '" '" '" '" '" '"
""
Rockwell "C ' is nOI applicable below lhi. range. Rockwen "8 " in br. cke lS
SA
""
"
" '"
Glossary of Terms Cem ...
"-1.5.1
........ enc ... Iron and Steel 'ns','Ule.
A.SM E. A.S.TM Acicular
""'_"" SocielV 01 MK"-nicI' Eng;neoers Ameo'I period wllen Ihe s,,,.1 I. h.,,
Alloy 5'H' Arm"aling Arrnt point
A".'empering Aulleni'e
""at
A cons,an, '"mpe",''''. ulnsformation prOCIU used lor small PIIn •. l(Ii'ingl. etc. fig 44 A solid solution 01 carbon in Iron
mainly
t".
C"I':" T"mperIlU"
Curie POtnt Olnnemorr. OIClrbu,lle
EN No.
8.SI.
a,inna
e""oh Standards Ins,,,,"'on. A ,trUClu •• obtain |
'""It
BiUet
Bodv Cemred Brine
C.st St..1
'"
Any process wh..:/'l eau"'" ~I"'" 01 cemon, A. ... rI.ce hardening pJOCeSS whictt .ell"" lhe no
,-
The ' .... per.,u" " wt.id, structural dwlnge. OCCUr on 11" mel.l. Us.ually, but 1101 _'}'S. coir",ident with 1"•. ""HI PoOn ..·• An """'rly .... ngement of atoms, IJlmoal .lwa}'S in preciH lI4'O"'e lric Ih,pe, Iron cryStalS I.e IIw.VI 01 cubic lorm. Th, tempe •• wr. abO';e which steal lOses 111 mllgnellC ",ope"ie" An i. onworks in Swl!(jen. which was 'epul"d to p,oduc, lIn iron remarkably ,," ' rom impurities. The reductron 01 c.rbon content us.u"lIy on s.urftce 01 t'" melal. CauHd •• I rul. by lhe IICI"", 01 oJ
I'"
The "Engrnee"ng Number" IM ident,rocation numbe, 01 sleels used in B S 970" 955.,- ""petSeded chart pIo",ng the ailic., tempe.,,,u'H 01 steelll>O<'tn$1 lhec..bonoonlent f;g 13. The oornposil>On 01 el which I'" _ ~r"'c.l lamperllIU'. coineidH witll lower. 'EutICloid" i t " , "entir.ty pel!rtihC. A
".
COI'I$lIn, low Temper.,ur •. le" ~d bul IOUgl1er thM1 Manensi, •. T'fPic .... ,he of 1Ws1.m~lng-. A $Quar. or ,..,'Ingul., bar. usually ,lie raw malef~llor I.ter hot lormirlg ptoc:_ Th. name given 10 t'" ItHI after the complelion of !hoo cemen"tion proce$S. Th, lurlaee of lhe melal is at thi, poinT covered In ICale bliStera. Applied 10 crvstals. On, w ith In I tOm" each co,ne. e'ld one in the geometric cenue 01 t'" laulce. (;on(:enlmled ""IUTion 01 commOn lilt ,N,Cn in w.'e'
The proceh by which Wroughl Iron is taused 10 absorb carbon th,ough t... lulill
EutlCloid
FICl! C"nt.ed FI9llotlng Ferri"
Gauge StOCk
It"' I""
Appohed to U'i'I1.,s. one ... ,," In atom at each corner and one in The cemre of 'l'Ch of the laces ol lhe lattice, The act of welding 1.lhe. b~fSOI Wrought Iron to make billets. MetallurlliCltI name 10< Ihe elmosl pu.e iron observed in t'" mic'OSlrucWra 01 (Not 10 be c:onlused with lhe ··s.inle red le.",,' used lor coil cores atC in _lectronic equ,pment.!
.",,1
SI"'
An oiI-h,,"""ng c.rborI-dlrom; ..... .,roy compoun· ded to reduce dislOIUOn on quenching to • minimum. Someti..- known H "ground aloc:k" Aw< .....IH 01 CIVIla'" The.. form when I'" me1l1 soIidifiH. but .... y chlnge the .. Ihape .nd di,,,o.mon _, it cools. A.ny proc:eH whkh aithe. reduces 0< mak... more uniform Ih .. &i~e oltha g"'nL
"at
G.tin A. llnemenl
'"
High C,rbon S'MI
S'M' w ith , c.lrbon content above 0. 8 5""- Mo<. .ccu,a'ely. I'''''' which Ihowl I'M Camenti'e in Ih. micJOlttu<:tur • • Usuelly , high"Clwomi .. m high_Tu"",ten IIlIoy with ..,h.need ho.-h&tdnns. but mlV not '" • sl ....1 I t , 11. "Stdit.~ is In elloy of CoMIT. Chromr .. m.nd TungSl.." will! no lton conlllnl.
,,,,,,hat ....
5.,..
Solidus
1200 numblt
The energy in foot-poundI 'MIII;,ed 10 lint"" , Sllndanl """;mom .. ndotr , p' ...... lbed imt:>aC1 10.... A tu. for shock ""Stlnc,.
Silver StMI u m lce UQuiduI Manempering
A "ameworir. 01 Imagln,,,, llnel lOining I'" location 01 "oms In I cryst al. The lempe'atu,e 'bove whl~h 'h' mel,lls , "'i,ely liquid. HUI lre.lmenl PfOUn de"gr'led 10 ,educe diSIOtIiOn on I. rge 0< complex componenlS. Fig. ' 5. The SHuClu" Iotmed wher1 • comblnalion 01 Au"""ill end Cam""li" il COIll l d 100 quietlV 10 ,11ow lhe norma' , .. nsfotmllion 10 P....i" . lhe Solid... and the The .., . of lemper.I .... Uqu;dus. where the metel ll in • PIOI'" IlIle. with bo.h solid end liquid .,.e-'I. A """.ce in which the wo11 di.ecl Impinoemenl of the hel'ing It il now ePQNed ,Iso 10 most e~!ric ''''''' Ince lumecet.
"'M""
M o....
sa"
No
T.mpe,ing
TT.T. Curve
n.....
A whictt Is uMd 11 • helling medium but w hich neither carburises nor declrbufisel lhe melll. A condilion whe .e ' h' I,on C"bida g,ainl are in the IOtm of nodule. "llIe, Ihan the no,m.1 n,edla-like ahape. Hu , UU tmenl intended la retlOre di9tonlld grains 10 thei, ,-",el shepe. A Iotm of grain relinemenl.
Puddling RN(cl
'"
A tlthelt;ng Pfocen which modifiM the .. ruct" .. of • ileaH""ed "MI. (NOli Ihlt in early booka lhe 11"""'" 01. 11", oft ... refefted to its carbon content). ·'Time-T."-al" .. trenslormlt"'" Curve _ "5' Cu .... of Fig 10. A ch.an wtlich shows lhe li .... IIk,n lot con ..en, tem"""u.. trens/OI"ml1ion of Sleel,
I'"
Any
c:n.nge
11"'
of '''' microscopic SltuCtu,. 01 chemical brougtll .bout by heal Irellm..,t.
coml)O»i tion of U,T.S.
Ultrm.te T..,,,le S t''''IIth. The Slrlls ., lhe breakrng paint. me'JUred uflder pn,scribed condition$ on • s tanda,d test pi.ece.
V.O P.
Vickerl Oilmond PYrlmid. Th. VO P numbe, Is. menure of ' h' hltd"",,. of lhe m.te,1,I.
Wroughtlton
The Predecessor to IIMI MHIe by dec.rbu,ising ClSl lrOfl in the pu(IdIing f,,'n.ce_
Yield Poinl
The IlreSl beyond which ....,,' will not .. tum to I1I oOginel lenglh wherI,he load la ,emoved
O H. & T. The "",m.1 tr.nslor .... tion prodUCI when Aultenite ;s IJoNtv ~'Xled Ihrough the IowfIr <;
Socie ty 10< Aulomol;'" Enginee .. (USAI, Curve .howlng t,_lotma.ion filM ag,lfllrl tempe .. ture ,nd lime (Fig, 161 "OfI o.lde Iorming 0fI the lurl_ of hol 51"" The condiTion where lhe Itoml of one solid IUbstlnc, ... disposed within lhe CrysT" lallice of Iaoou. 10 the more usullliquid lIOIution. T.mperlIU" ~ which lhe me,,' ..."i.etv solid I,on-carbon elloy wi th. carbon tonlent between 0.0' " and I,n(.. 8efore.bout 18S5 the IMm w;os ""i-..1Iy epfIIied only to -- High Carbon 51'""-- el wtI know it High Carbon StMI 10 85 14 07 5<>--c.Illed bee.use 11 I. usulllv g.ound.oo 10 Pre .. nlS a ",ilvery" Ippe8r.nce. in cOfllrlSt 10 Ihe normal ··bl.ck"' 1001 sleel of earlier d.y,. TY!>Ic,lIy 1. 1- 1 2" Cerbon. 03..().4% Manag.nes". 0.40.5" Ch,omium. 0 . 1"().25% Silicon, and mulm. 01 0.35% Sulphur & Phosphorus.
Rodewe" Hardness '"1 number. 0fI Ill. " c"' .cll1e . thoe OM normally used 10< herd mlt.nall. Th. ne me somelimes ulld 10< the critical "mpe
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