Abstract

The process of the austenite grains growth in the samples of carbon steel grades «ER 7» and «2» with different initial structural state under heating in a temperature range of 810–1300 °C has been investigated. It has been shown that the structure of austenite remains fine-grained to the temperature of 900 °C both in the samples of ingot and of the continuous casting billets. It has been defined that the temperature of the beginning of intensive growth of austenite grains (collective recrystallization) for steel of the grade «ER 7» with 0.4–0.5 wt.% C is ~1000 °C, and of the grade «2» with 0.5–0.6 wt.% C – ~1100 °C independently of the incoming billet type. It has been established that the microstructure of the continuously cast billet samples under heating to a hot deformation temperature of wheel billets is characterized by 30 % smaller average grain size compared with the austenite structure of the ingot samples.