Influence of Machining on Low Temperature Surface Hardening of Stainless Steel

The main goal of low temperature surface hardening of austenitic stainless steels is a significant increase of surface hardness while at the same time maintain the superior corrosion resistance of these alloys. The treatment temperature has to be low enough to achieve a precipitation free diffusion zone, yet high enough to allow sufficient diffusion depths needed for technical applications. The results are often influence by the machining of parts prior to the surface treatment. Best results are usually achieved on solution annealed and (electro-)polished surfaces, but customer needs for certain manufacturing routes, strength considerations and overall production costs often don’t allow for such additional processes.

This paper shall give and basic overview on machinability of austenitic stainless steels and how different machining operations like turning, cold forming, grinding and additive manufacturing influence the result of low temperature surface hardening.

Possible machining process optimizations for the different machining operations are presented in order to increase diffusion depth, surface hardness, reproducibility and corrosion resistance without altering the hardening process parameters.