Mathematical modelling of plasma nitriding of austenitic stainless steel

Abstract

34, Ekaterinburg, Russian Federation. Tel.: +7 (343) 375 35 92; fax: 3745330 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. Gavrilov N.V., Men'shakov A.I. A source of broad electron beams with a self-heated hollow cathode for plasma nitriding of stainless steel. Instruments and Experimental Techniques, 2011, vol. 54, no. 5, pp. 732-739. DOI: 10.1134/S0020441211050046. 4. Gavrilov N.V., Menshakov A.I. Low-temperature nitriding of stainless steel in electron beam plasma at 400 ºС. Fizika i khimiya obrabotki materialov, 2012. no. 5, pp. 31-36. (In Russian). 5.Lo K.H., Shek C.H., Lai J.K.L. Recent developments in stainless steels. Materials Science and Engineering: R: Reports, 2009, vol. 65, iss. 4-6, pp. 39-104. DOI: 10.1016/j.mser.2009. Laleh M., Kargar F., Velashjerdi M. Low-Temperature Nitriding of Nanocrystalline Stainless Steel and Its Effect on Improving Wear and Corrosion Resistance. Journal of Material Engineering and Performance, 2013, vol. 22, iss. 5, pp. 1304-1310. DOI: 10.1007.Makarov A.V., Skorynina P.A., Osintseva A.L., Yurovskikh A.S., Savray R.A. Improving the tribological properties of austenitic steel 12Kh18N10T by nanostructuring frictional treatment.

Mathematical simulation of plasma nitriding of stainless steel in view of the effect of residual stresses

“…(2) in view of the effect of both residual stresses and internal stresses caused by introduced nitrogen atoms. By comparing the results with the solution of the problem (1), (2) obtained at zero residual stresses [9], we can conclude that the presence of residual stresses of the form discussed, as well as the account of internal stresses induced by diffusion, accelerates nitrogen diffusion. …”