PHYSICO-CHEMICAL MODELING OF PHASE SEPARATION IN FE-21.4 CR STEEL WITH 1.14 MO TAKING INTO ACCOUNT CROSS FACTORS

Abstract

Physicochemical modeling of diffusion phase transformation and determination of the long-term microstructural stability of the Fe-21.4 Cr alloy with 1.16 Mo taking into account cross factors has been carried out. A conventional Fe-21.4 Cr alloy is used as a reference material. The article proposes an integral approach to modeling phase separation in chromium alloys, combining the determination of diffusion coefficients and fluxes of elements, taking into account their dependences on the concentration and an assessment of the mutual diffusion of elements. The calculated values of diffusion fluxes are used to calculate the current concentrations of carbon and chromium in the alloy and the size of chromium formations. They show that the thermal stability of the Fe - 21.4% Cr alloy with 1.16% Mo is much higher than without molybdenum. In alloy Fe – 21,4 % Cr – 1,16 % Mo at a temperature of 973 ° K, the chromium concentration during the same operation time decreases three times slower with the formation of inclusions of the σ-phase about 6 microns in size.