Work Hardening of Stainless Steel Sheet

A. 304 is not considered to be a hardenable grade of SS. You will see a warpage of the material because you are removing material from one side which normally reduces the surface stress causing it to bow.

A. As a quick, unscientific answer, the answer is that the surface will probably not be effected. Reasons are many and dependent on type of wheel used. The harder and the stiffer the wheel material the more possible the effect. Meaning, if you use steel wire, it might be possible. Soft cotton buffs with abrasive is not likely. Work hardening with mechanical processes involves compacting the surface molecules and this can only be done with pressure.

A. Paul:

First Q: Absolutely yes. You can harden almost any commercial metal by mechanical work. Even nonferrous metals such as copper and aluminum (who has not bent a piece of copper wire and see it become stiffer?). Only difference with heat treatment is penetration of this effect.

Second Q: A possibility is to avoid micro surface deformation (flowing of the metal) and shift to micro surface elimination (cutting of the metal). In other words: sandpapering and low speed hand polishing will leave less hardening effect than high speed brushing.

A. You can harden by heat treatment those of the 400 series that are martensitic stainlesses, but not those of the 400 series that are ferritic stainlesses. Which 400-series grade(s) did you trial?

You cannot harden 316 by any heat treatment. You can harden it by cold-work (deformation). Subsequent annealing will totally destroy any work-hardening and will return the material to the previous soft condition that existed before you deformed it.

I believe that stamping blanks will not change the hardness of the material, as it does not deform the material. Cold rolling is all that is available to you, and the more you deform it the harder it will get, up to a point. You control the final hardness by controlling the amount of cold rolling.

A. Charles,

As Mr. Reynolds explained, austenitic stainless steels like Type 316 don't respond to typically quench hardening treatments. I think what the manufacturer was trying to recommend was an austenitic stainless steel like Type 301 or Type 302 that is cold rolled (if in strip form) or cold drawn (if in wire form), then form the desired shape, then perform a low temperature aging treatment (sometimes referred to as stress relieving, annealing, or tempering although none of them is technically correct). I encourage you to contact a supplier of cold rolled stainless steel strip to discuss the application in detail.

A. The more cold deformation, the higher the hardness. The small amount of deformation just from curving the nib would give a small increase in hardness. Whether that increase is enough for your application, is for you to determine by trial.

My expectation would be that you would need to cold roll for hardness and expect no significant benefit from curving the nib - but that's my expectation, not the result of any trial that I've carried out.

A. Try using 410 SS. If you cannot heat treat that to a desired hardness, I seriously doubt if you would ever be able to work harden 316 enough.

A. Hi Ben!

No, 304 and 316 are almost identical when it comes to mechanical properties. Those are going to be determined by the amount of cold working the material has seen, so you can get annealed, quarter-hard, half hard, full hard, etc with both rods and sheet. Thick things like plate are going to be annealed, and low hardness.

Stronger non-magnetic stainless steels would include the Nitronic series (Nitronic 40, Nitronic 50, Nitronic 60) and A286 precipitation hardenable stainless steel.

Good luck!

A. A hard austenitic stainless steel alloy would work nice for you.

A. Hi Zara. Per BSAA, '80' is just cold worked harder than '70' :-)
https://www.bssa.org.uk/cms/File/Microsoft%20Word%20-%20SSAS2.31-Fastener%20Grades%20A1,A2_A3_%20&%20A4_A5_%20to%20BS%20EN%20ISO%203506.pdf

Regards,