Residual stresses in surface layer of M2HSS steel after conventional and low pressure ("NITROVAC'79") nitriding processes

The distribution of residual stresses in the surface layer of M2HSS steel after conventional and low pressure ("NITROVAC79") nitriding is reported and discussed in this paper. The stresses depend on the structure of the nitrided layer, which results from the applied nitriding parameters. The optimum structure has been obtained after low pressure nitriding at ammonium partial pressure p=20 hPa. Cyclic annealing after nitriding at temperatures below nitriding temperatures doesn't cause any significant changes in residual stresses' distribution. Annealing temperatures higher than resorted at nitriding, causes a well-marked increase of residual stresses in surface layer of the steel.