关键词: C-Mn-Si系贝氏体钢, C含量, CCT曲线, 相变点, 组织

Abstract: Dilatation curves of C-Mn-Si series low carbon （/% : 0.11C , 1.15Si, 1.85Mn, 0.032A1, 0.003Ti, 0.002 4N） and medium carbon （/% ： 0.35C, 1.1 ISi, 1.82Mn, 0.041 Al, 0.002Ti, 0.004 2N） bainite steel continuous cooling with cooling rate 0.5 ~ 30 ℃/s have been measured by using thermal dilation method and metallographic examination with the Gleeble-1500 hot simulation machine to define the phase transformation points, and combined with microstructure observation, the continuous cooling transformation （ CCT） curves of two steels are respectively plotted by Origin software. Results show that with cooling rate ≤ 1 °C/s, the structure of 0. 11% C steel is ferrite + bainite + martensite, as cooling rate ≥ 2 °C , its structure is bainite + martensite, and with cooling rate ≥ 0.5 °C/s the 0.35% C steel has bainite 4- martensite structure ； with increasing carbon content, the transformation temperature of bainite and martensite all decreases.