MATHEMATICAL MODELING OF DIFFUSION LAYERS FORMATION USING COMPOSITIONAL SATURATING BATCHES CHARGES

Анотація

The problem of chemical-thermal treatment of steel using composite saturating charge ECD (Energy component of diffusion). In the system under consideration, a complex of processes occurs: wave propagation in the charge layer on the steel surface, non-stationary heat removal into the interior of the sample, and non-stationary diffusion of atoms of the saturating element deep into the steel under non-isothermal conditions. In this case, that part of the surface from which the diffusion saturation of steel occurs expands as the wave moves. In this work, the thermal conductivity l is not an additive, but a structure-dependent quantity. However, for simplicity, in the area where ECD occurs, the additive formula is usually adopted: l = l_ch(1–h) + l_prh,  and for steel l = l_st. For the i-th individual substance, a linear dependence of thermal conductivity on temperature was used: l_i(T) = l₀ + l_TT. After the ECD wave has reached the edge, i.e. the charge has fully reacted, the diffusion of atoms from the surface and conductive heat transfer in the steel continue during the holding time t_h. This problem is two-dimensional, nonstationary, and essentially nonisothermal.