MATHEMATICAL MODELS OF NITROGEN CONCENTRATION PROFILE OF ION NITRIDED LAYERS AND COMPUTER SIMULATION

The mathematical models of the kinetics of the layer growth at different ion nitriding condi-tions of armco iron.steels 45,40Cr,42CrMo and 38CrMoAl have been established.Based onthese models the expression of nitrogen concentration profile of ion nitrided layers have beendeduced with profile simulating method.They areC_=C_(min)~+(P_4)/(ξ_1-x)+(P_5)/(ξ_(10)~2)(ξ_1-x)~2C_(γ′)=C_(min)~(γ′)+(P_1)/(ξ_(21))(ξ_2-x)+(P_2)/(ξ_(21)~2)(ξ_2-x)~2C_α=C_(min)~α+(C_(33))/(C_(33))/(ξ_(32))(ξ_3-x)~3Using these models,the kinetics of layer growth and the nitrogen concentration profile of ionnitrided layers were sinulated on Apple-Ⅱ computer.Results show that the simulated curvescoincide quite well with the experimental data.