203 vs. 303 galling/wear 1

[btrueblood]

Have an application for a stainless shaft operating in a brass plain bearing (C37700 forged brass, 38-40% zinc, 1-2% lead, Cu rem.). Looking at a screw-machined shaft piece of either 203 or 303 stainless, it looks like they are roughly equivalent for corrosion resistance, but I'm not sure if the copper in the 203 might increase or decrease its tendency to gall against a copper-alloy bearing, any comments?

 

[metengr]

btrueblood;
Are you sure about the copper content? The 203 grade of stainless steel reported by SSINA in their Designer Handbook reports a higher manganese content to offset nickel in 3xx series stainless steel. The Mn content for 203 stainless steel is between 5-6.50% by mass.

 

[metengr]

btrueblood;
Oops, I just saw in this same table that copper was specified between 1.75 - 2.25% by mass. Anyway, after further review of my "Handbook of Stainless Steels" by Peckner and Bernstein, the effect of copper has more to do with the ability of austenitic stainless steels to strain harden based on the change in the strain hardening exponent as a function of Ni content. To summarize, the change in strain hardening exponent decreased from 0.5 to 0.42 for three different Ni contents that converged at 2.0% copper content by mass.

 

[metengr]

btrueblood;
Just as a follow-up to completely answer your post having addressed the copper question, ASM Handbook, Volume 18 provides some wear and galling data for comparing various grades of austenitic stainless steels (self-mated and dissimilar).

I could not re-produce the tables, but the trends are obvious - the 2XX series austentic stainless steels have at least equal to or better wear and galling resistance in relation to other materials and austenitic stainless steels (3XX) that were compared. The general theme was resistance related to high work hardening rate.

 

[btrueblood]

Thanks, metengr, confirms the limited data I could scrounge up.