针对一种辙叉用贝氏体钢,采用Gleeble-3500对其焊接热循环过程进行了热模拟试验.采用光学显微镜、扫描电子显微镜、透射电子显微镜和硬度试验对不同冷却速度下焊接热影响区的组织和性能进行研究.作出加热和冷却膨胀曲线,并采用切线法测定奥氏体转变开始温度(Ac1)、奥氏体转变结束温度(Ac3)和不同冷却速度下的相转变温度.根据试验结果绘出辙叉用贝氏体钢的焊接热影响区连续冷却转变(simulated heat affected zone continuous cooling transforming,SHCCT)曲线,为其焊接性研究提供了基础数据,并用于预测热影响区的组织和性能,可用于指导贝氏体钢辙叉焊接及焊补工艺的优化设计.
Gleeble-3500 was used to simulate the thermal cycle processes of bainite steel used for frog. The microstructure and properties of HAZ were investigated by optical microscopy(OM), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and hardness test, respectively. The start temperature of austenite transformation, the end temperature of austenite transformation and the phase transition temperatures under different cooling rates were measured by the tangent method from the expanding curves. According to the experimental results, the simulated heat affected zone continuous cooling transforming(SHCCT) diagram of the bainite steel was constructed.SHCCT diagram provides basic data for the research of its weldability. It could be used to predict microstructure and properties of HAZ and optimize welding and repair welding processes of bainite steel frog.