The Corrosion in the Railway Wagon Revision

2011 The Corrosion In The Railway Wagon

Nurhasanudin Metallurgical Departement 11/25/2011

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Contents

Page Preface ............................................. .................................................................... ............................................. ...................................... ................ 3 Corrosion That May Occur In Railway Wagon........................................ ........................................ 4 Causes Of Corrosion In Railway Wagon ........................... ................................................. ........................ .. 7 Areas Subject To High Rate Of Corrosion In Passenger Wagon .......... 10 Prevention ............................................ .................................................................. ............................................ ................................. ........... 11 Conclusion ........................................... ................................................................. ............................................ ................................. ........... 13 References References ............................................ .................................................................. ............................................ ................................. ........... 14







Preface

Railway is a public transportation which is always be a choice for the t he most people to do travel to cross many place. The railway work out in many environment and cilmate which vary like marine atmospheric, industrial atmospheric, and even as dry season, and rainy season the railway still operated Due to the impact such as environment and climate, the body of railway wagon can be corroded easily, which will affect the transportation safety and maintenance of wagon body.

Picture 1. The railway with corrosion problem

This railway unit was in very poor condition with a big corrosion problem. Thats way we need to investigated more about corrosion problem in railway especially the wagon body.







The Corrosion That May Occur in Railway Wagon

The pictures below are examplize the corrosion in the wagon body that may occur

(a)

(b) (c) Picture 2. Corrosion in the window hopper Source : The International Railway Preservation Society Picture 2 showing the corroded window hopper. The hooper frame made from brass strip act as holder and joined to the along side of alumunium plat to holding the alumunium in place, place, and form. form. Picture 2. (a) is the hopper before installation, picture 2 (b) and (c) showing the hopper after usage. After usage, the along side of alumunium has completely powdered through. The picture 2 (c) showing where the alumunium has powdered. This is probably caused by the close proximity of different metals and the presence of water. Aluminium is the less noble of this combination of metals and electrolysis







crevice

(a)

(b)

Galvanic corrosion

(c) (d) Picture 3. the corrosion in the : (a), (b) vestibule ; (c) end vestibule ; (d) roof Picture 3 showing the area that corroded in more specific area in wagon. The uniform corrosion is occur in almost all of the surface area in the vestibule, end vestibule and the roof. The corrosiove environment must have the same access to all part of the metal surface and the metal it self must be matallurgically and compositionally uniform [Deny A. Jones, 1992] . The picture 3 (a) showing the most serieous damage caused by uniform corrosion. The arrow in picture 3 (b) showing the area with crevice corrosion. Corrosion within a crevice maybe coused in atmospheric exposures by retention of water, while the outer surface can drain and dry.







If the crevice is made up of differing alloys or if the deposit is conductive (magnetite or or graphite) crevice corrosion may may be compounded by galvanic galvanic effects. [Deny A. Jones, 1992] The arrow in picture 3(c) is pointing to the area with galvanic corrosion problem which occur in coupled pillar beetwen b eetwen two dissimilar metal alloys. When two dissimilar alloys are coupled in the presence of a corrosive electrolyte one of them is preferentially corroded, while the other one is protected from corrosion. Based galvanic series, metal with more negative potential will corroded, and the more positif one will be protected. [Deny A. Jones, 1992] The railway wagon, in the selection material still use a different material which are coupled togather because there is amount of advantages. In design of window hopper, hopper, there was two kind of different metal are used, used, alumunium and brass. Aluminum is lighter material, and have a good look, but it self have a disadvantages, alumunium is less tough. In the other hand, brass have a good toughness but more heavy. For that reason, those two material get combined. Improved stiffness, Reduced density/weight, density/weight, so the t he window hopper could be moer lighter, but have a good toughness.









Couses Corrosion In Railway Wagon

Coaches are susceptible to marine atmospheric corrosion and industrial atmospheric corrosion Table 1. Environmental pollutan causing corrosion







Atmospheric variable: 1. Climate condition Metal surface located in areas where they become wet and retain moisture generally corroded more rapidly then surfaces exposes to rain. The rain has a tendency to wash the surface and remove particles of dust that can lead to differential aeration corrosion, exception would be areas that subject to acid rain. 2. Time of wetness Time of wetness is a critical variable with respect to the extent of corrosion experienced. The time of wetness determines the duration of the electrochemical process. The thickness and the chemical composition of the water film are both important The critical relative humidity is the humidity below which water will not form on a clean metal surface and thus electrochemical or wet corrosion will not occur. The actual relative humidity will change depending on the surface th condition of the metal [ASM Handbook, 9 ed., volume 13: Corrosion, 1992] Marine Atmospheric Corrosion: Sea water and open seas has a hidh salt content of about 3,5%. The table salt ( sodium chloride ) makes sea water a good conductor of electricity, as the presence of an electrolyte is necessary for corrosion, it leads to corrosion. In the marine atmospheric corrosion, chloride ions play a major role in inducing corrosion. Approaching the sea coast, air is laden with increasing amounts of sea salt, in particular NaCl. Sulfates exert a lesser influance, bicarbonates hinder corrosion Industrial atmospheric corrosion At industrial area, appreciable amounts of SO2, this converts to sulfuric acid, and lesser amounts of H2S, NH3, NO2 and various suspended salts are encountered. This is the main reason for coaches getting easily corroded near







5. Absence of surface preparation during replacement of commode and drain pipes 6. Habits of flushing the flooring with the water jet f or cleaning 7. The condition of air trapped in between trough floor and flooring due to climate changes 8. Striking of flying ballast when the train is running. 9. Design of window seal leaves the gap between the side panel to allow the rain water flow through the panel and to drain out at the th e bottom. 10. Blockage of drain water by accumulated dust on top of trough floor 11. Dissimilar metals joint 12. Design allow space







Areas Subject To High Rate Of Corrosion In Passenger Wagon

Areas subject to high rate of corrosion in passenger wagon are : 1. 2. 3. 4. 5. 6. 7. 8.

Trough floor: areas adjacent to lavatory, doorways, luggage compartment in SLR (sleeper) and kitchen area of pantry car. Side wall bottom: area below lavatory and between body side pillars Body pillars: bottom portion of pillar near doorways and lavatory area Cross bearers: joint between sole bar and cross bearers. Body side door: bottom of door due to accumulation of dust Battery boxes: corrosion due to acid action Roof: ventilator and area around it. Joint between frame ( carbon steel ) and roor (stainless steel)







Prevention

In order to overcome corrosion, the following steps are carried out: 1. Use of HSLA : CORTEN Steel 2. Use of corrosion resistant material like l ike stainless steel 3. Surface preparation and painting (organic coating) 4. Use simillar metals which are welded or joined togather Corten Steel : Corten steel (often referred to as Cor – Ten) Ten) is a weather resistant steel which could more accurately be termed as an "Atmospheric Corrosion Resistant Steel" It is a copper chromium alloy steel – this alloy displays a greater level of resistance to atmospheric weathering when compared to other unalloyed steels. It's chemical composition promotes the early formation of an adhering protective layer of rust when exposed to the elements. Weathering steel, best-known under the trademark CORTEN A steel and sometimes written without the hyphen as "CORTEN A steel", is a group of steel alloys which were developed to obviate the need for painting, and form a stable rust-like appearance if exposed to the weather for several years. United States Steel Corporation (USS) holds the registered trademark on the name CORTEN A. The original CORTEN A received the standard designation ASTM A 242 TYPE-1("COR-TEN A") from the ASTM International standards group. Newer ASTM grades are A 588 ("CORTEN A") and A 606 for thin sheet. All alloys are in common production and use. JIS G 3125:2004 Japanese grade for weather resistant steel plates . Superior atmospheric corrosion resisting rolled steels steels This Standard specifies specifies the rolled steel steel having high atmospheric corrosion resistance, to be used for vehicle, building, steel tower and other structure. IRSM 41-97 Corrosion Resistance Steel Indian grade for weather









Table 3. Mechanical Properties Corten A (source: www.ajmarshall.com www.ajmarshall.com))

Table 4. Mechanical Properties Corten B (source: www.ajmarshall.com www.ajmarshall.com))

Use Of Stainless Steel And Hsla And Mild Steel Which Are All Welded Together When under going dissimilar welding, defects are caused because of change in metal composition. Under such conditions, corrosion in dissimilar parts can be minimized if the weld metal has better corrosion resistance, strength and mechanical properties compared to the parent metal. For e.g. when welding stainless steel to mild steel, the composition of weld metal should be closer to that of stainless steel composition. The usage of copper coated plain carbon steel wire as electrode under CO2 as shielding media is the usual practice that deviates from







Conclusion

The sorrosion may occur in the corrosive atmospheric Corrosion can be mitigated by : a) Avoiding usage of dissimilar metals b) Use simple design c) Good coating and the preparation or cleaning cl eaning d) Choose a material with a good resistant to the corrosion Joining two material that have a very diferent character is able to do, to get a different charcteristic.







References

th ASM Handbook, 9 ed., volume 13: Corrosion, 1992 Denny A. Jones, Principles and Prevention of Corrosion, Macmillan Publishing Co, New York, 1992 Sivakumar, Durgacharan. CORROSION PREVENTION IN RAILWAY COACHES , TRI-Service Corrosion Conference, Conference, 2007 Triyono; Diharjo K.; Ilman Nur & Soekrisno. Fakultas Teknik UNS, Penelitian, Dikti, RUT, 2005. www.ajmarshall.com www.irps-wl.org.uk/3916.shtml www.mastell.co.uk/corten-weather-resistant-steel.htm

The Corrosion in the Railway Wagon Revision

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