C-Mn-Si系超级贝氏体钢连续冷却转变（CCT）曲线

采用热膨胀法和金相法,通过Gleeble-1500热模拟试验机测定C-Mn-Si系低碳(/%:0.11C、1.15Si、1.85Mn、0.032Al、0.003 Ti、0.002 4N)和中碳(/%:0.35C、1.11Si、1.82Mn、0.041Al、0.002 Ti、0.004 2N)贝氏体钢在0.5～30℃/s的冷却速度下连续冷却时的膨胀曲线,确定相变点,并结合显微组织,借助Origin软件分别绘制出两种钢的连续冷却转变(CCT)曲线。结果表明,0.11%C钢当冷却速度≤1℃/s时获得铁素体+贝氏体+马氏体组织,冷却速度≥2℃/s时为贝氏体+马氏体组织,0.35%C钢冷却速度≥0.5℃/s即可获得贝氏体+马氏体组织;随碳含量增加,贝氏体和马氏体转变温度均降低。

Continuous Cooling Transformation Curves of C-Mn-Si Series Super-Bainite Steel

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,1.11Si,1.82Mn,0.041A1,0.002Ti,0.0042N) 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℃/s,the structure of 0.11%C steel is ferrite + bainite + martensite,as cooling rate≥2℃,its structure is bainite + martensite,and with cooling rate≥0.5℃/s the 0.35%C steel has bainite + martensite structure;with increasing carbon content,the transformation temperature of bainite and martensite all decreases.