Optimization of the ion-plasma nitriding of structural steel

Abstract

Mathematical planning was used in order to determine the optimal mode for ion nitriding the structural steel 0.38C-2Cr-2Ni-Mo. This was justified by the requirement to preserve strictly limited functional parameters obtained as a result of diffusion saturation: hardness in the range of 450-650 HV in a layer 0.15-0.40 mm deep. According to of X-ray diffraction analysis in addition to reflections from the matrix phase (alloyed ferrite α-Fe), the reflexes of nitride compounds are recorded, namely, the γ′-phase with a FCC lattice (Fe4N) and the ϵ-phase with a HCP lattice (Fe3N) with a high nitrogen content. An analytical expression in the form of a linear function for the studied optimization parameters (microhardness and depth of nitration) was obtained by implementing factor planning and regression processing of the obtained data. This made it possible to assess the degree and direction of influence of the investigated factors on the optimization parameters under study. © Published under licence by IOP Publishing Ltd.