Track pins

[tankbarrell]

Normal, i.e. mild steel does not have enough carbon to be heat treated, that is why case hardening powders are used as these are carbon based.

You can buy a carbon case hardening steel such as EN32 or a nickel chrome moly such as EN24. Both can be heat treated with the EN24 giving a uniform toughness throughout.

As Maurice said, Stainless steel is not very hard but it does have the advantage of work hardening.