Nitriding behavior and corrosion properties of AISI 304L and 316L austenitic stainless steel with deformation-induced martensite

摘要

AISI 304L and AISI 316L are metastable austenitic stainless steels, which exhibit a good corrosion resistance due to their chromium contents but suffer from poor mechanical properties and therefore exhibit poor wear resistance. A slight hardening effect is gained by the formation of deformation-induced martensite either by cold rolling or shot-peening. A considerable surface hardness could be achieved by plasma nitriding processes due to the formation of the so-called S-phase, the nitrogen diffusion zone. In industrial manufacturing processes cold-deformation could not be avoided and no final annealing is carried out to eliminate the deformation-induced martensite. Therefore, the knowledge about the behavior of the microstructure regarding the nitriding process and the resulting properties is fundamental. The S-phase is also assumed to improve the corrosion resistance if the plasma nitriding is performed below a critical temperature. Above this temperature chromium nitrides precipitate in the matrix and decrease the corrosion resistance.