热处理对汽车用马氏体高强钢组织和力学性能的影响

Effect of Heat treatment on Microstructure and Mechanical Properties of High Strength Martensitic Steel for Automobile

采用盐浴炉对B800NQ钢进行了不同加热温度和时间的淬火,用扫描电镜对热处理试样显微组织进行了观察,并用万能拉伸试验机对力学性能进行了检测。结果表明,淬火温度为930℃时,显微组织主要是板条马氏体,随着加热时间的增加马氏体组织变化不大,力学性能略有提高;淬火温度为960℃时,显微组织全部为板条马氏体,随着加热时间的增加,马氏体板条略有粗化,屈服强度逐渐降低,抗拉强度和伸长率先略有增加,在超过60 s时有所降低。

The quenching at different temperatures for different heating time of B800NQ steel was carried out by using salt bath furnace. The microstructure of the heat treated sample was observed by scanning electron microscope, and the mechanical properties were detected with the universal tensile testing machine. The results show that, when quenching temperature is 930℃, the microstructure is mainly the lath martensite. With the increase of heating time, the martensite microstructure changes little, and the mechanical properties increase slightly. When quenching temperature is 960℃, the mierostructure is total lath martensite. With the increase of heating time, the martensite lath coarsens slightly, the yield strength decreases, gradually and the tensile strength and elongation firstly increase slightly and then decreases when heating time exceeds 60 s.