Tempering of martensitic stainless steel with 0.6 w/o nitrogen and/or carbon

Martensitic stainless high nitrogen steels are used for advanced bearings because of their superior corrosion resistance and hot hardness. Therefore the tempering behaviour of steels SC, SN and SNC with close to 15 w/o Cr, 1 w/o Mo and 0.6 w/o C, N or C+N, respectively, was investigated. Secondary hardening is enhanced by nitrogen, which also increase the content of retained austenite and its resistance to tempering especially in SNC. During tempering epsilon-, theta- and M7C3-carbides precipitate in SC while epsilon-, zeta- and M2N-nitrides appear in SN. In SNC carbides and nitrides precipitate separately. Mossbauer spectroskopy revealed clustering of solute atoms in SC and ordering in SN and more so in SNC.