C-Mn-Ni高强钢的连续冷却相变研究

采用Formastor-FII相变仪和MMS-300热模拟实验机，研究了低锰、中锰钢在不同开冷温度及不同变形量条件下的连续冷却相变，建立了实验钢的连续冷却转变曲线，分析了贝氏体及马氏体的相变规律。结果表明，随着冷却速率的增加，低锰钢依次经过粒状贝氏体、板条贝氏体及马氏体相区，中锰钢只经过马氏体相区，在较宽的冷却速率范围内，均可获得马氏体组织；随着开冷温度的降低或冷却速率的提高，低锰钢的贝氏体相变开始温度和中锰钢的马氏体相变开始温度均有所降低；随着冷却速率的增加及开冷温度的升高，实验钢的显微硬度值均有所升高；变形促进了低锰钢粒状贝氏体相变，其显微硬度值降低，变形细化了中锰钢马氏体组织，其显微硬度值升高。

Study on phase transformation of C—Mn—Ni high strength steel during continuous cooling

The phase transformation behaviors of low and medium manganese steels during continuous cooling at different start cooling temperatures and amount of deformation conditions were investigated by means of Formastor—FII phase transformation testing instrument and MMS—300 thermo mechanical simulator.The continuous cooling transformation curves were established,and the phase transformation behaviors of bainite and martensite were analyzed.The results show that the granular bainite,lath bainite and martensite are obtained successively with the increasing of cooling rate for low manganese steel,and the martensite is obtained in a wide range of cooling rate for medium manganese steel.The bainite transformation start temperature for low manganese steel and the martensite transformation start temperature for medium manganese steel decreases with the decreasing of start cooling temperature or increasing of cooling rate.The micro hardness increases with the decreasing of start cooling temperature or increasing of cooling rate for both steels.The micro hardness decreases for low manganese steel because of more granular bainite induced by strain,and the micro hardness increases for medium manganese steel because of finer martensite obtained by strain.