Austenite Grain Growth Behavior of 30BF Steel Before Rough Rolling

To investigate the effect of heat treatment on the grain size of austenite in 30BF steel, the comparisons of the morphologies and sizes of austenite grains between heating samples were made with a high-temperature electric resistance furnace, and the austenite growth models were built with method of mathematics. The results show that most grains in original specimen with the sizes below 70 μm uniformly distributed. At a heating rate ( v ) of 10 °C/s, the grain size ( d ) value under a certain time ( t ) increased by 60–100 μm with raising temperature ( T ) from 850 to 1100 °C, whereas the d value under a certain T merely increased by 70–120 μm with raising time to 60 min. Under v = 0.1 °C/s, T = 850 °C, and t = 0 s, the occupied ratio of grains with sizes of 40–50 μm was 0.165, whereas at 900 °C, the occupied ratio was 0.125. The evolutions of ln d 5.8 - d 0 5.8 with 1/ T were in negative linear correlations, whereas the ln d 5.8 - d 0 5.8 with ln t were in positive linear correlations. To sum up, the grain growth behavior of steel was elucidated.