MODELING OF PHASE TRANSFORMATIONS DURING COOLING OF ALLOY STEELS

Abstract

Modern studies on the modeling of phase transformations in low-alloy steels to a certain extent allow solving the problem of quantitative determination of phase transformations for a given chemical composition of steel and different cooling rates. However, the capabilities of the available universal software products for the analysis of complexly alloyed steels are currently very limited. To conduct research, steels 25Cr2Mo1V and 38CrNi3MoV and existing analytical models were used, which were adapted to carry out the corresponding calculations. Structural diagrams are plotted for the steels under study depending on the rate of continuous cooling. The amount of residual austenite was taken into account by the developed method for the first time. Steel 25Cr2Mo1V, with continuous cooling at a rate of 1.0 °C/s (conditions close to natural air cooling), consists of 18 % ferrite, 1 % pearlite, 80 % bainite and 1 % residual austenite. Steel 38CrNi3MoV cooled at a rate of 1.0 °C/s consists of 2 % ferrite, 47.5 % bainite, 50 % martensite and 0.5 % retained austenite. It is shown that for the conditions of natural air cooling, the calculated data correlate well with practical results.