Railcars and Chromweld?

[ssabuk]

What is the aim of using a soft stainless steel for rail cars when I would have thought that a wear plate would be better? Especially when carrying aggregate. The hardness of this material is only ~200HB and I find it difficult to beleive that corrosion resistance would be a bigger concern than wear resistance. Surely a high grade wear plate would last a lot longer. What do you think?

 

[rustbuster1]

This is a simple concept. If the steel does not corrode and in fact forms a very rugged, very thin oxide film on its surface, then unless the abrading material can gouge this film from the surface or damage it by deforming the steel, the abrasion resistance in rail cars is excellent. Without severe surface wear (because the aggregate is not pushed into the surface), the stainless steels just sit there - immune to what a colleague calls "corrbrasion"

On the other hand, carbon steels - even the abrasion-resistant grades - corrode from rain or wetness in the product, aggregates, coal, etc. The resulting corrosion product is weak and easily removed by the sliding action of the material. Continuous repetition of this process leads to high corrosion rates.
There are stainless steels that are harder AND LOWER PRICED than 304. Duplex stainless steel such as Usinor 2304 (S 32304) probably provides a significantly better combination of properties - strength, and corrosion resistance - than the 300 stainlesses. You should also look into the 12-Cr stainless steels - like Cromweld 3CR12, which has been widely used in the application you describe.

Happy transporting!

 

[arunmrao]

Sudies on usage of stainless steel instead of wear resistant carbon steel for rail car applications have shown that the former has a distinct advantage. Also the frequency at which the rail car needs to be maintained is extended to a period of five years or more as against less than one year for the conventional carbon steel. In one of the past issues of Nickle magazine published by NIDI there is a photograph of an accident where the rail car was constructed in stainless steel and no major damage occurred due to better impact absorbing capacity as claimed in that article.I would suggest you to read more about it in this article