Ensayos de Dureza

INSTITUTO POLITÉCNICO NACIONAL UNIDAD INTERDISCIPLINARIA DE INGENIERÍA Y CIENCIAS SOCIALES Y ADMINISTRATIVAS

LICENCIATURA EN INGENIERÍA INDUSTRIAL UNIDAD DE APRENDIZAJE: PRUEBAS APRENDIZAJE:  PRUEBAS DE LA CALIDAD PARA LA INGENIERÍA PROFESOR: TRÁNSITO PROFESOR: TRÁNSITO GALLEGOS BARRIENTOS ALUMNO: RA ALUMNO: RAMIREZ MIREZ RETANA RETANA PAULINA PAULINA 2IV55 TRABAJO FINAL: ENSAYOS DE DUREZA ROCKWELL, BRINELL, TEORIA Y APLICACIÓNES. FECHA DE ENTREGA:

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Contenido INTRODUCCION...................................................................................................3 1. ENSAY ENSAYOS DE DUREZA.. DUREZA....... .......... .......... .......... .......... .......... .......... ......... ......... .......... .......... ............... .................... .................5 .......5 2. DUREZA DUREZA BRINELL. BRINELL...... ......... ......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... ................ ....................7 .........7 2.1 PENETRADORES........... PENETRADORES.............................. ....................................... ........................................................... ....................................... 9 2.2 TIEMPOS DE APLICACIÓN DE LA L A CARGA.......................................... CARGA................................................... ......... 10 2.3 ALCANCE Y APLICABILIDAD DEL MÉTODO BRINELL.................................. BRINELL..................................10 10 3. DUREZA DUREZA ROCKWEL ROCKWELL... L........ ......... ......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... ............. ............ ....11 11 3.1 CARGAS PENETRADORES PENETRADORES Y ESCALAS............................... ESCALAS...................................................... .......................12 12 3.2 DUREZA ROCKWELL SUPER!ICIAL.............................. SUPER!ICIAL................................................. .............................. ........... 15

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INTRODUCCION La durea e! "a #$#!%&%'( )ue $re!e(*a u( +a*er%a" a !er ra,ad# # $e(e*rad# $#r  #*r# &uer$# !'"%d#- La de.%(%&%'( de durea e! d%.ere(*e a "a de re!%!*e(&%a +e&/(%&a0 "a &ua" e! "a re!%!*e(&%a de" +a*er%a" a !er de.#r+ad#- La durea *a+1%( e! u(a +ed%da de "a! $r#$%edade! de a1ra!%'( de u( +a*er%a"Ge(era"+e(*e0 "#! +a*er%a"e! +/! dur#! $re!e(*a( +e3#re! $r#$%edade! a "a a1ra!%'( )ue #*r#!S#( +4"*%$"e! "a! u*%"%dade! )ue "#! re!u"*ad#! de "a +ed%&%'( de durea e( "#! +a*er%a"e! (#! $uede( $r#$#r&%#(ar- A"u(#! de "#! u!#! 6a1%*ua"e! de "a +ed%&%'( de "a durea !#( &#+4(+e(*e:  7 A(a"%ar "a 6#+#e(e%dad de u( +a*er%a" 7 C#+$r#1ar "a 6#+#e(e%dad de u( *ra*a+%e(*# 7 B4!)ueda de .a""#! e( !#"dadura! , e(!a+1"e! 7 O1*e(er "a re!%!*e(&%a a" de!a!*e 7 E8a"uar a$r#9%+ada+e(*e "a re!%!*e(&%a a *ra&&%'(La durea (# e! e9a&*a+e(*e u(a $r#$%edad de" +a*er%a"0 !%(# )ue de$e(de de #*ra! $r#$%edade! &#+# "a e"a!*%&%dad0 "a $"a!*%&%dad , "a e!%'(- De 6e&6#0 u*%"%a+#! e" *r+%(# durea $ara de.%(%r &#(&e$*#! *a( d%!*%(*#! &#+# "#! !%u%e(*e!:  7 Durea a" ra,ad#  7 Durea a "a $e(e*ra&%'( # %(de(*a&%'(  7 Durea a" %+$a&*# # &a$a&%dad de re1#*e  7 Durea a" de!a!*e # a1ra!%'( E( "a $re!e(*e %(8e!*%a&%'( re&a1e %(.#r+a&%'( !#1re d#! e(!a,#! de durea e( $ar*%&u"ar0 R#&;e"" , Br%(e""0 "#! &ua"e! !#( e(!a,#! de durea a "a $e(e*ra&%'( &#+4(+e(*e &#(#&%d#! &#+# %(de(*a&%#(Par*%e(d# de!de "a *e#r
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1. ¿QUÉ ES DUREZA? La durea0 a$"%&ada a "a +a,#r#!- C%er*a+e(*e0 &#+# u(a $r#$%edad +a*er%a"0 !u 8a"#r e %+$#r*a(&%a (# $uede( !u1e!*%+ar!e0 "a %(.#r+a&%'( de u(a $rue1a de durea $uede &#+$"e+e(*ar , u!ar!e a +e(ud#  3u(*# &#( #*ra! *&(%&a! de 8er%.%&a&%'( de +a*er%a"e! *a"e! &#+# *ra&&%'( # &#+$re!%'( $ara $r#$#r&%#(ar %(.#r+a&%'( &r<*%&a de re(d%+%e(*#- ?@u *a( %+$#r*a(*e , 4*%" e! e" +a*er%a" , "a $rue1a de durea C#(!%dere "a %(.#r+a&%'( $r#$#r&%#(ada , !u %+$#r*a(&%a e( "a e!*ru&*ura0 aer#e!$a&%a"0 au*#+#*r%0 &#(*r#" de &a"%dad0 a(/"%!%! de .a""a! , +u&6a! #*ra! .#r+a! de .a1r%&a&%'( e %(du!*r%a- La de*er+%(a&%'( de e!*a! $r#$%edade! de" +a*er%a" $r#$#r&%#(a u(a 8%!%'( 8a"%#!a de "a dura1%"%dad0 re!%!*e(&%a0 ."e9%1%"%dad , &a$a&%dade! de u(a 8ar%edad de *%$#! de &#+$#(e(*e!0 de!de +a*er%a! $r%+a! 6a!*a e!$e&<+e(e! $re$arad#! , $r#du&*#! *er+%(ad#!- A "# "ar# de "#! a>#!0 !e 6a( de!arr#""ad# , e+$"ead# d%8er!#! +*#d#! $ara de*er+%(ar "a durea de "#! +a*er%a"e! &#( d%.ere(*e! (%8e"e! de 9%*#- De!de "a! $r%+era! .#r+a! de $rue1a! de ra!&ad# 6a!*a "a !#.%!*%&ada %+ae( au*#+a*%ada0 "a! $rue1a! de durea 6a( e8#"u&%#(ad# 6a!*a &#(8er*%r!e e( u( +*#d# de $rue1a de +a*er%a"e! e.%&%e(*e0 $re&%!# , 8a"%#!# A(*e! "a! .#r+a! 1/!%&a! de $rue1a! de durea0 &#+# "a $rue1a !%+$"e de" ra!u># 1a!*ar#( $ara !a*%!.a&er "a (e&e!%dad de e!*ud%# de "a durea- A"u(a! de "a! .#r+a! +/! *e+$ra(a! de "a $rue1a de" ra!u># de "a 1arra da*a( a"reded#r  de 22- E!*a! $rue1a! !e 1a!ar#( e( u(a 1arra )ue au+e(*' e( durea de e9*re+# a e9*re+#- E" (%8e" a" )ue e" +a*er%a" )ue !e e(!a,a $uede .#r+ar u( ra!u># e( "a 1arra e! u( .a&*#r de*er+%(a(*e e( "a durea de "a! +ue!*ra!P#!*er%#r+e(*e0 e( 220 !e %(*r#du3er#( .#r+a! de e(!a,# de durea )ue %(&"u
durea- E" $e(e*rad#r &#(!*a1a de u( &#(# *ru(&ad# )ue !e e!*re&6a1a de!de 5 ++ e( "a $ar*e !u$er%#r 6a!*a 025 ++ e( e" $u(*#- E!*e +*#d# .ue +/! e.%&a e( +a*er%a"e! 1"a(d#!- O*ra .#r+a *e+$ra(a de $rue1a de %(de(*a&%'( %+$"%&a1a $re!%#(ar e#+e*r
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2. ENSAYOS DE DUREZA Se e(*%e(de $#r durea "a $r#$%edad de "a &a$a !u$er.%&%a" de" +a*er%a" de re!%!*%r a "a de.#r+a&%'( e"/!*%&a0 $"/!*%&a # a "a de!*ru&&%'( e( $re!e(&%a de a&&%#(e! de &#(*a&*# "#&a"e! %(.er%da! $#r #*r# +a*er%a" +/! dur#0 )ue (# !e !#+e*e a "a de.#r+a&%'( re!%dua" de" &uer$# %(de(*#r # $e(e*rad#r de de*er+%(ada! .#r+a! , d%+e(!%#(e!- E!*a a.%r+a&%'( e! 8/"%da (# $ara *#d#! "#! +*#d#! e9%!*e(*e!0 de 8a"#r%a&%'( de "a durea- La 8ar%edad de e!*#! +*#d#! , e" !e(*%d# .a! # ra(de! de.#r+a&%#(e! $"/!*%&a! , de re!%!*e(&%a de "#! +a*er%a"e! a !u de!*ru&&%'(P#r "a a+$"%*ud de !u u*%"%a&%'(0 "#! e(!a,#! de durea0 !#1re *#d# a "a *e+$era*ura a+1%e(*e0 &#+$%*e( &#( "#! e(!a,#! +/! d%.u(d%d#! de *ra&&%'( e!*/*%&a- E!*# !e e9$"%&a $#r !u !%+$"%&%dad , a"*# re(d%+%e(*#0 $#r au!e(&%a de de!*ru&&%'( de "a +ue!*ra0 "a $#!%1%"%dad de 8a"#rar "a! $r#$%edade! de "#! d%.ere(*e! &#+$#(e(*e! e!*ru&*urar"e! , &a$a! .%(a! e( u( /rea de $#&a e9*e(!%'(0 $#r e!*a1"e&er &#( .a&%"%dad "a re"a&%'( e(*re "#! re!u"*ad#! de "a $rue1a de durea , "#! da*#! de #*r#! +*#d#! de e(!a,#!- A" +ed%r "a durea e( "a &a$a !u$er.%&%a" de "a $r#1e*a u1%&ada de1a3# de" %(de(*#r !ure u( e!*ad# de *e(!%'( &#+$"e3#0 $r'9%+# a "a &#+$re(!%'( 8#"u+*r%&a0 )ue !e &ara&*er%a $#r u( +a,#r  &#e.%&%e(*e de 1"a(dura 2 e( &#+$ara&%'( &#( #*r#! *%$#! de e(!a,#! +e&/(%&#!- P#r e!*e +#*%8#0 e( e" &a!# dad# !#( $#!%1"e! "a #1*e(&%'( de e!*ad#! $"/!*%&#! , "a 8a"#r%a&%'( de "a durea $r/&*%&a+e(*e de *#d#! "#! +a*er%a"e!0 %(&"u!# de "#! +e*/"%&#! +u, .r/%"e!L#! +*#d#! e9%!*e(*e! de +ed%&%'( de "a durea !e d%!*%(ue( (#*#r%a+e(*e u(#! de #*r#! $#r "a .#r+a de" %(de(*#r u!ad# $#r "a! &#(d%&%#(e! de a$"%&a&%'( de "a &ara , $#r e" +*#d# de &a"&u"ar "a durea- La e"e&&%'( de" $r#&ed%+%e(*# de de*er+%(a&%'( de "a durea de$e(de de d%.ere(*e! .a&*#re!: durea de" +a*er%a" de "a +ue!*ra $%ea !u! +ed%da!0 e!$e!#r de "a &a$a &u,a durea 6a de !er  de*er+%(ada e*&E( .u(&%'( de "a 8e"#&%dad &#( )ue !e a$"%&a "a &ara0 "#! $r#&ed%+%e(*#! de de*er+%(a&%'( de "a durea !e d%8%de( e( e!*/*%&#! , d%(/+%&#!0 , !e4( e" +*#d# de a$"%&a&%'( de "a +%!+a e!*#! !#( de $e(e*ra&%'( , de ra,ad#- L#! +/! 7

d%.u(d%d#! !#( "#! $r#&ed%+%e(*#! de de*er+%(a&%'( de durea e( "#! &ua"e! !e u!a "a $e(e*ra&%'( e!*/*%&a de" %(*e(d#r e( e" !e(*%d# $er$e(d%&u"ar a "a !u$er.%&%e de "a +ue!*raE( *#d#! "#! $r#&ed%+%e(*#! de e(!a,# de durea e! +u, %+$#r*a(*e $re$arar "a &a$a !u$er.%&%a" de "a +ue!*ra- E!*a &a$a de1e $#!eer0 e( "a +ed%da de "# $#!%1"e0 "a! &ara&*er#! &#(!%dera1"e!0 e*&- *%e(e( )ue !er e"%+%(ad#!- La! e9%e(&%a! &#(&er(%e(*e! a "a &a"%dad de "a !u$er.%&%e )ue !e e(!a,a de$e(de( de" %(de(*#r e+$"ead# , de "a +a(%*ud de "a &ara )ue !e a$"%&a- Cua(*# +e(#r !ea "a $r#.u(d%dad de "a $e(e*ra&%'( de" %(de(*#r0 *a(*# +/! "%+$%a de1e 6a""ar!e "a !u$er.%&%e de e(!a,# , *a(*# +/! e!*r%&*a+e(*e !e de1e #1!er8ar )ue (# !e &a+1%e( "a! $r#$%edade! de "a &a$a !u$er.%&%a" a &#(!e&ue(&%a de" e(dure&%+%e(*# $#r de.#r+a&%'( e( .r%# # &a"e(*a+%e(*# &ua(d# !e e.e&*u e" e!+er%"ad# # 1ru>%d#La &ara *%e(e )ue a$"%&ar!e $#r e" e3e de" %(de(*#r )ue $e(e*ra #r%e(*/(d#!e $er$e(d%&u"ar+e(*e a "a !u$er.%&%e )ue !e e(!a,a- Para )ue e!*a! &#(d%&%#(e! !e &u+$"a(0 e" $"a(# de "a !u$er.%&%e e( e(!a,# de "a +ue!*ra de1er/ !er  e!*r%&*a+e(*e $ara"e"# a "a !u$er.%&%e de a$#,#- La! +ue!*ra! )ue !#( $"a(a! !e !u3e*a( !#1re $"a*%(a! de a$#,# e!$e&%a"e! )ue .#r+a( $ar*e de" e)u%$# de +ed%d#re! de durea- L#! re!u"*ad#! de "#! e(!a,#! de durea de$e(de( de "a dura&%'( de "a a$"%&a&%'( de "a &ara a" %(de(*#r de $e(e*ra&%'( , de "a dura&%'( de" +a(*e(%+%e(*# de e!*e 1a3# "a &ara- C#( u(a &#(!*a(*e P0 "a d%+e(!%'( "%(ea" de "a 6ue""a e! 2

d =b τ 

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e! e" *%e+$# de +a(*e(%+%e(*# de" %(de(*#r 1a3# "a &ara

10( !#( &#e.%&%e(*e! )ue de$e(de( de "a! $r#$%edade! de" +a*er%a" , de "a +a(%*ud de "a &ara P0 e( de$e(de(&%a de

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- "a durea de "ara dura&%'( !e e8a"4a a

*e+$era*ura! +/! e"e8ada! , !e u!a &#+# &ara&*er
P#r e!*# "a 6ue""a #1*e(%da de!$u! de re*%rar "a &ara de1e !er $#r !u! +ed%da! !%(%.%&a*%8a+e(*e +a,#r )ue "a! +ed%da! de "#! ra(#! de "#! d%.ere(*e! &#+$#(e(*e! e!*ru&*ura"e! e" d%/+e*r# # "a "#(%*ud de "a d%a#(a" de "a! 6ue""a! e( "a +ed%&%'( de "a durea 8ar%a de =-K=-2 ++ 6a!*a u(#! +%"<+e*r#!- La d%!*%(&%'( %(e8%*a1"e e( "a e!*ru&*ura de "a! d%.ere(*e! $ar*e! de "a +ue!*ra &#(du&e a "a d%.ere(&%a de 8a"#re! de "a durea- E!*a d%.ere(&%a e! *a(*# +a,#r  &ua(*# +e(#r e! "a d%+e(!%'( de "a 6ue""a-

3. DUREZA BRINELL  A .%( de +ed%r "a durea Br%(e"" !e4( GOST =2K5 U(a 1#"a de a&er# de d%/+e*r# D !e 6a&e $e(e*rar e( "a +ue!*ra )ue !e e(!a,a0 &#( u(a &ara P a$"%&ada dura(*e u( "a$!# de*er+%(ad#- U(a 8e )u%*ada "a &ara !e +%de e" d%/+e*r# d de "a 6ue""a de3ada $#r "a 1#"a !#1re "a !u$er.%&%e de "a +ue!*raE" e(!a,# de durea 1r%(e"" &#(!%!*e e( $re!%#(ar "a !u$er.%&%e de" +a*er%a" a e(!a,ar &#( u(a 1#"%""a de a&er# +u, dur# # &ar1ur# de *u(!*e(#0 $r#du&%(d#!e "a %+$re!%'( de u( &a!)ue*e e!.r%&# &#rre!$#(d%e(*e a "a $#r&%'( de "a e!.era )ue $e(e*ra E" 8a"#r de durea0 (4+er# de Br%(e"" HB0 re!u"*a de d%8%d%r "a &ara a$"%&ada P $#r "a !u$er.%&%e de" &a!)ue*e0 $#r "# )ue:  H B =

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P Kg πDh mm2

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La $r#.u(d%dad 6 de" &a!)ue*e %+$re!# !e +%de d%re&*a+e(*e e( "a +/)u%(a0 +%e(*ra! "a &ara !e +a(*%e(e a$"%&ada de +#d# de a!eurar u( 1ue( &#(*a&*# e(*re "a 1#"%""a , e" +a*er%a"- O*ra +a(era de de*er+%(ar e" (4+er# HB e! $ar*%e(d# de" d%/+e*r# d de "a %+$re!%'( "# &ua" *%e(e "a 8e(*a3a de )ue !e $uede( e.e&*uar  *a(*a! +ed%&%#(e! &#+# !e e!*%+e( (e&e!ar%a! , e( +%&r#!&#$%#! # a$ara*#! e!$e&%a"+e(*e d%!e>ad#! $ara *a" .%(- E( e!*e &a!# e" 8a"#r de" d%/+e*r# de "a %+$re!%'( re!u"*ar/ de" $r#+ed%# de d#! "e&*ura rea"%ada! a = e(*re !
( ) ()  D 2

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2

 E&. 2  D  D h = −∝= −√ ¿ 2

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Ree+$"aa(d# "a E)- 2 e( "a E)-  !e #1*%e(e u(a e9$re!%'( $ara e" (4+er# de Br%(e"" e( .u(&%'( de" d%/+e*r# de "a 6ue""a: 9

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''''''''''''''''''''''((((((((((((((((((((((((((((((((((((((((((((

E( "a $r/&*%&a e" (4+er# de Br%(e"" !e $uede *#+ar d%re&*a+e(*e de u(a *a1"a %(re!a(d# &#( e" 8a"#r de" d%/+e*r# de "a %+$r#(*a- E( a"u(#! +a*er%a"e! "a $e(e*ra&%'( de "a 1#"%""a #r%%(a u(a &ra*er%a&%'(:

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10

 E( e!*#! &a!#! "#! 8a"#re! #1*e(%d#! a $ar*%r de "a +ed%&%'( de 6 (# &#%(&%de( &#( "#! #1*e(%d#! e( .u(&%'( de d0 ,a )ue "a $r#.u(d%dad 6 +ed%da (# &#rre!$#(de a" &a!)ue*e &u,# d%/+e*r# e! d0 !%(# a" de d%/+e*r# d0 &u,a de*er+%(a&%'( e9a&*a e( .#r+a $r/&*%&a e! d%.%&u"*#!a- P#r *#d# e!*# !e 6a e(era"%ad# "a de*er+%(a&%'( de HB a $ar*%r de d0 ,a )ue #.re&e +a,#r !eur%dad de u(a de*er+%(a&%'( &#rre&*aQa !ea e( "a0 de*er+%(a&%'( de 6 # e( "a de d0 !e re)u%ere u(a $re&%!%'( +<(%+a de =0=++-

3.1 PENETRADORES C#+# $e(e*rad#r (#r+a" de" +*#d# Br%(e"" $uede &#(!%derar!e "a 1#"%""a de = ++ de a&er# +u, dur# HB  = $ud%e(d# e+$"ear!e0 e( $r#1e*a! de +e(#r  e!$e!#r0 $e(e*rad#re! de 5 , 205 ++0 a&e$*/(d#!e e( &ua")u%er &a!# u(a *#"era(&%a de =0==5DTa+1%( !e e+$"ea( $e(e*rad#re! de 025 , =025 ++ de &ar1ur# de *u(!*e(# )ue $er+%*e( e(!a,ar +a*er%a"e! +/! dur#!0 au()ue "#! e(!a,#! (# !#( &#+$ara1"e! &#( "#! rea"%ad#! &#( "#! #*r#! *%$#! de 1#"%""a!- E9%!*e( d%8er!#! &r%*er%#! $ara de*er+%(ar "a 1#"%""a a u*%"%ar e( u( e(!a,#- La! (#r+a! IRAM e!$e&%.%&a( )ue e( (%(4( &a!# !e e(!a,ar/( $r#1e*a! &u,# e!$e!#r e !ea +e(#r  )ue e" d%/+e*r# de" $e(e*rad#r D0 +%e(*ra! )ue "a! ASTM %(d%&a( )ue e (# de1e !er +e(#r de= 8e&e! "a $r#.u(d%dad de $e(e*ra&%'(- La (#r+a ASTM e!$e&%.%&a "a durea +<(%+a re)uer%da $ara !a*%!.a&er "a &#(d%&%'( e=6 $ara u( e!$e!#r de $r#1e*a de*er+%(ad# , d%!*%(*a! &#(d%&%#(e! de &ara11

Espesor de l pro!e" e #p$l%ds&    W 5 

D$re' (r)*ell +,*)+ pr l -$l $* e*s.o (r)*ell p$ede o/re-er se%$r)dd Cr% de 011 2% Cr% de 3011 2% Cr% de 4111 2% == = =2 5= 5= =  == 2= 25 5 5= 2= = 2=  5= ==

Relaciones entre dureza, espesor de la probeta y carga a aplicar según ASTM

ESPESOR DE LA PRO(ETA e 5++6 DIAMETRO DE LA (OLILLA D 5++6

e>6

3
e<3

=

5

2-5

Criterio para seleccionar el diáetro del penetrador 

C)*+), %-/%)), De a&uerd# a "a! (#r+a! ASTM "a! &ara! e!*/(dar !#( "a! de ===0 5== , 5== ;0 $#r "# )ue &#(!%dera(d# )ue e" $e(e*rad#r (#r+a" e! e" de = ++0 "a re"a&%'( =025D < d < =05D  !e &u+$"e $ara +e*a"e! &u,a durea Br%(e"" !e e(&ue(*ra &#+$re(d%da e(*re "#! !%u%e(*e! 8a"#re! Cara === ; $ara durea! de = a ==

(ol)ll 31 ++

Cara 5== ; $ara durea! de = a == Cara 5== ; $ara durea! de 2 a ==

!alores de C según los criterios de la nora ASTM

P#r #*ra $ar*e0 de a&uerd# &#( "#! d%!*%(*#! d%/+e*r#! de "#! $e(e*rad#re! , &#(!*a(*e! de e(!a,#0 *#+ada! e( 1a!e a "a (a*ura"ea de" +a*er%a"0 !e 6a( &#(.e&&%#(ad# *a1"a! &#+# "a *a1"a !%u%e(*e )ue $er+%*e &#(#&er d%re&*a+e(*e "a &ara a e+$"ear $ara &ada +a*er%a" , e!$e!#r de $r#1e*aM"er)les8 Co*s"*"es de E*s.o . Cr%s #9%& D)7+e"ro de l !ol)ll #++&

 Acero !  "#$%&c&'$ c()* 

 A+ec&o$e %e C# ! A+  C ( -* 

Core !  +#/&$&o C ( 0 

P+o/o, e12o !  +ec&o$e C ( 3,0 

=

===

===

5==

25=

5

5=

25=

25

2-5

2-5

-5

2-5

-2

5-

-25

W-

5-

-

-

12

=-25

-

-

-5

=-

Carga en "unci#n del   penetrador y la naturaleza del aterial a ensayar 

3.2 TIE!POS DE APLICACI"N DE LA CAR#A E( e(!a,#! (#r+a"e! "a &ara +/9%+a !e a"&a(a e( u( "a$!# de 5 ! , !e +a(*%e(e0 a" +e(#!0 dura(*e #*r#! 5 ! $ara a&er#! , = ! $ara +e*a"e! +/! d4&*%"e!- S%( e+1ar# a +e(ud# "a &ara +/9%+a !e re*%e(e dura(*e u( %(*er8a"# de = ! $ara "#! +e*a"e! .err#!#! , u( %(*er8a"# de = ! $ara "#! #*r#! +e*a"e!L#! a$ara*#! de &%&"# au*#+/*%&# $er+%*e( rea"%ar e(!a,#! a a"*a 8e"#&%dad0 $#r "# )ue e" *%e+$# de *ra(!%&%'( de "a &ara , e" *%e+$# e( )ue !e re*%e(e "a +%!+a $uede( !er +u&6# +e(#re! a "#! +e(&%#(ad#!S%( e+1ar#0 e!*#! *%e+$#! *%e(e( %(."ue(&%a e( e" 8a"#r de durea #1*e(%d#- S% "a 8e"#&%dad de a$"%&a&%'( de "a &ara e! +u, a"*a0 e! de&%r e" *%e+$# de &re&%+%e(*# de "a &ara e! +u, &#r*#0 !e $uede $r#du&%r u(a !#1re&ara "a &ara !#1re$a!a e" 8a"#r de e(!a,# a(*e! de e!*a1%"%ar!e )ue $r#du&%r/ u(a 6ue""a de +a,#r  d%/+e*r#- P#r #*r# "ad# !% e" *%e+$# )ue !e re*%e(e "a &ara e! %(!u.%&%e(*e $ara )ue e" +a*er%a" &#+$"e*e e" ."u3# $"/!*%� e" *a+a># de "a 6ue""a !er/ +e(#r- E( e!*e !e(*%d# !e 6a #1!er8ad# )ue $ara "a +a,#r# de "a %+$r#(*a $er+%*e #1*e(er u( +e3#r $r#+ed%# de "a durea e( "a #(a Ade+/! !% !e u*%"%a "a $r#.u(d%dad h de "a %+$r#(*a $ara "a de*er+%(a&%'( de "a durea0 "a !u$er.%&%e a e(!a,ar (# re)u%ere de+a!%ada $re$ara&%'(- C#+# re"a e(era": &ua(*# +a,#r e! "a 6ue""a +e(#r e! e" re)uer%+%e(*# de $re$ara&%'( !u$er.%&%a"-

13

$. DUREZA ROC%&ELL  A" %ua" )ue e( e" e(!a,# Br%(e"" "a durea !e de*er+%(a e( .u(&%'( de" rad# de $e(e*ra&%'( de "a $%ea a e(!a,ar a &au!a de "a a&&%'( de" $e(e*rad#r 1a3# u(a &ara e!*/*%&a dada- D%.%ere de" e(!a,# Br%(e"" e( )ue "a! &ara! !#( +e(#re! , "#! $e(e*rad#re! +/! $e)ue>#! $#r "# )ue "a %+$r#(*a !er/ +e(#r , +e(#! $r#.u(da- Ade+/! e" e(!a,# R#&;e"" (# re)u%ere "a u*%"%a&%'( de .#r+u"a a"u(a $ara "a de*er+%(a&%'( de "a durea- E!*a !e #1*%e(e d%re&*a+e(*e de" d%a" %(d%&ad#r  de "a +/)u%(a ,a )ue "a +%!+a e!*/ dada $#r e" %(&re+e(*# de $r#.u(d%dad de $e(e*ra&%'( de1%d# a "a a&&%'( de" $e(e*rad#r0 e" &ua" $uede !er u(a 1#"%""a de a&er# # u( &#(# de d%a+a(*e- E( "a #$era&%'(0 "a &ua" !e +ue!*ra e!)ue+/*%&a+e(*e e( "a F%0 !e a$"%&a %(%&%a"+e(*e u(a &ara de = ; "a &ua" &au!a u(a $e(e*ra&%'( %(%&%a"  A )ue $#(e e" $e(e*rad#r !#1re e" +a*er%a" , "# +a(*%e(e e( $#!%&%'(- E" %(d%&ad#r de "a +/)u%(a !e $#(e e( &er#0 e! de&%r !e *#+a "a "<(ea de re.ere(&%a a $ar*%r de "a &ua" !e +ed%r/ "a %(de(*a&%'( , !e a$"%&a "a &ara ad%&%#(a"0 "a )ue e(era"+e(*e e! de 5= # = ; &ua(d# !e u*%"%a &#+# $e(e*rad#r u(a 1#"%""a de a&er# , e! de W= ; &ua(d# !e u*%"%a e" &#(# de d%a+a(*e-

1"

 A" a$"%&ar "a &ara ad%&%#(a" e" +a*er%a" ."u,e $"/!*%&a+e(*e0 re!u"*a(d# u(a $e(e*ra&%'( *#*a" B- P#!*er%#r+e(*e0 !e re*%ra "a &ara ad%&%#(a"0 $er+%*%e(d# "a re&u$era&%'( e"/!*%&a de" +a*er%a" re!u"*a(d# u(a $e(e*ra&%'( .%(a" C - U(a 8e )ue "a &ara $r%(&%$a" !e re*%ra0 e" 8a"#r de durea !e "ee d%re&*a+e(*e de" %(d%&ad#r de "a +/)u%(a , de$e(der/ de "a $e(e*ra&%'( h dada $#r "a d%.ere(&%a e(*re "a "<(ea de re.ere(&%a A , "a "<(ea .%(a" C E( "a! +/)u%(a! &#( !%!*e+a de %(d%&a&%'( a(a"'%&# "a &ar/*u"a ""e8a d#! ru$#!0 )ue d%.%ere( $#r = (4+er#! de durea0 e( "#! )ue !e aru$a( "a! d%.ere(*e!

e!&a"a! &#rre!$#(d%e(*e! a" +*#d# U(# de "#! ru$#! &#rre!$#(de a "a! e!&a"a! )ue u*%"%a( e" $e(e*rad#r e!.r%� +%e(*ra! )ue e" #*r# &#rre!$#(de a "a! )ue u*%"%a( e" &#(# de d%a+a(*eLa! e!&a"a! R#&;e"" *%e(e( d%8%!%#(e! de =0==2 ++0 e! de&%r "a d%.ere(&%a de $e(e*ra&%'( e(*re "e&*ura! HRB  5 , HRB  5 e! de =0== ++- C#+# "a! e!&a"a! e!*/( %(8er*%da! u( (4+er# +/! a"*# %+$"%&a +a,#r (4+er# R#&;e"" e" &ua" e!*/ dad# $#r  HR = E – h

D#(de E e! e" (4+er# *#*a" de d%8%!%#(e! de "a e!&a"a , $e(e*ra&%'(

h

e! e" %(&re+e(*# de

$.1 CAR#AS' PENETRADORES Y ESCALAS C#+# !e e9$"%&' "a &ara a$"%&ada re!u"*a de u(a %(%&%a" &u,# 8a"#r e! de = ; e( *#d#! "#! &a!#! , #*ra ad%&%#(a" de 5=0 =0 = # W= ;0 de a&uerd# a" +a*er%a" a e(!a,arP#r #*r# "ad#0 *a+1%( !e +e(&%#(' )ue "#! $e(e*rad#re! $uede( !er 1#"%""a! de a&er# # 1%e( u( &#(# de d%a+a(*e &u,a $u(*a *%e(e rad%# de =02 ++ , u( /(u"# de 2=De e!*a +a(era e! $#!%1"e #1*e(er d%!*%(*a! &#+1%(a&%#(e! de &ara! , $e(e*rad#re! e( "a a&*ua"%dad e9%!*e( 5 &#+1%(a&%#(e! # e!&a"a! d%!*%(*a! )ue !e %de(*%.%&a( &#( "a! "e*ra! A0=0B0 C0 D0 e*&-

15

E( "a! *a1"a! !e +ue!*ra( "a! 5 e!&a"a! &#( !u! &#+1%(a&%#(e! de &ara $e(e*rad#r , "#! +a*er%a"e! e( "a! )ue !e u*%"%a &ada u(aP#r e!*e +#*%8# e( e" (4+er# de durea de1e %(d%&ar!e "a e!&a"a u*%"%ada0 de e!*a .#r+a HRC !%(%.%&a durea R#&;e"" e!&a"a C &#(# de d%a+a(*e , u(a &ara *#*a" de5= ;- C#+# !e $uede 8er e( "a *a1"a $ara +e*a"e! , a"ea&%#(e! dura! !e u*%"%a e" &#(# de d%a+a(*e &#( u(a &ara *#*a" de 5= ;Cua(d# !e e(!a,a( +a*er%a"e! +u, 1"a(d#! !e u*%"%a( 1#"%""a! de  , X &#( &ara! de =0== , 5= ;-

DUROMETRO NORMAL ESCALA

PENETRADOR

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