低碳硅-锰系Q＆P钢的热处理工艺及实验室研究

Experimental research and heat treatment process of low carbon Si-Mn Q&P steel

在GLEEBLE3800热模拟机上模拟了低碳Si．Mn系Q＆P（Quenching and Partitioning）钢的控冷热处理工艺。结果表明，Q＆P钢具有高的抗拉强度（σb=1050MPa）和良好的塑性（δ=25％）。采用扫描和透射电镜进行了组织观察与分析，发现其组织主要由板条马氏体和8％～15％的残留奥氏体组成，残留奥氏体呈膜状。利用XRD技术对残留奥氏体进行了定量分析并用扫描电镜进行了断口观察。结果表明，拉伸试样纤维区为比较典型的韧窝状形貌，体现出良好的韧性断裂特征，残留奥氏体在组织中起到了相变诱发塑性的作用。

The heat treatment process of low carbon Si-Mn Q＆P steel was investigated by the thermo-mechanical simulator,and its tensile properties were also tested. The results show that the high tensile strength（σb = 1050 MPa） and the high total elongation（δ =25% ）can be obtained by Q＆P process. Its microstructure was observed by means of SEM and TEM. It is shown that the microstructure of Q＆P steel is lath martensite and retained austenite （8% - 15% ）. The fracture mechanism of Q＆P steel was clarified based on examination to the fracture surface of specimens with scanning electronic microscope. The results show that the fracture morphology of the low carbon Si-Mn Q＆P steel is a dimple pattern with features of tough fracture. The retained austenite play a role of phase transformation induced plasticity.