L. F. Spevak, O. A. Nefedova, A. V. Makarov, G. V. Samoilova

MATHEMATICAL MODELLING OF PLASMA NITRIDING OF AUSTENITIC STAINLESS STEEL

Two mathematical models of diffusion are discussed as applied to the description of ion nitriding of austenitic stainless steel in electron beam plasma. One model is based on the assumption of the diffusion coefficient dependent on concentration, and this corresponds to the nonlinear boundary value problem of diffusion. The other model takes into account the effect of internal stresses, occurring in the surface layer and induced by introduced nitrogen atoms, on the diffusion process, and this leads to the inhomogeneous boundary value problems of diffusion. Algorithms for solving the boundary value problems are proposed, which are based on the boundary element method. Model examples have been solved to illustrate the functioning of the algorithms.

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