Features of Austenite Formation in Low-Carbon Steel upon Heating in the Intercritical Temperature Range

The features of austenite formation upon continuous heating of low-carbon steel at the rates of 90-0.15 K/s in the intercritical temperature range (ICTR) have been studied. It has been found that, in the initially high-tempered, initially quenched, and initially cold-deformed steel, the alpha -> gamma transition in the ICTR consists of three stages. The thermokinetic diagrams of the austenite formation with the indication of the positions of the critical points Ac-1 and Ac-3 and also of the temperature ranges of the development of each identified stage of the alpha -> gamma transformation have been constructed. A complex of structural studies has been carried out, and a scheme of the austenite formation upon continuous heating at a rate of 90 K/s in the ICTR for the initially high-tempered steel, initially quenched steel, and initially cold-deformed low-carbon steel has been suggested, which reflects all stages of this process.