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采用双相区保温—淬火—配分工艺对低碳硅锰钢进行热处理,通过扫描电镜、X射线衍射仪和拉伸试验等,研究了不同淬火温度对Q&P钢组织及力学性能的影响。结果表明:当淬火温度为220℃时,试验用钢综合力学性能最佳,抗拉强度达到1 400 MPa,延伸率为13.3%,强塑积达到18 620 MPa·%,随着淬火温度的升高,试验用钢的抗拉强度呈逐渐降低的趋势,塑性有所增大,室温组织中板条马氏体含量逐渐减少,碳化物颗粒逐渐增多,出现少量块状马氏体组织;双相区Mn元素向奥氏体的扩散补充了Q&P过程中碳配分的不足,最终室温残余奥氏体由两部分组成:一是少量富碳的残余奥氏体,另一部分则是经碳配分的富锰残余奥氏体,而淬火温度220℃的选取最为合理,为试验用钢提供了较好的塑性。
The low carbon Si-Mn steels were heat-treated by dual-phase zone heat-quenching-fractionation process. The effects of different quenching temperatures on the microstructure and mechanical properties of Q & P steel were studied by scanning electron microscopy, X-ray diffraction and tensile tests. The results show that when the quenching temperature is 220 ℃, the mechanical properties of test steel are the best, the tensile strength reaches 1 400 MPa, the elongation is 13.3% and the strong plastic product reaches 18 620 MPa ·%. With the increase of quenching temperature High, the tensile strength of the test steel showed a gradual downward trend, the plasticity has increased, room temperature tissue lath martensitic content gradually decreased, carbide particles gradually increased, a small amount of massive martensite; biphasic The diffusion of Mn into the austenite in the zone complements the deficiency of carbon partitioning in the Q & P process. The final room temperature residual austenite is composed of two parts: one is a small amount of carbon-rich residual austenite and the other is carbon-rich Manganese retained austenite, and the quenching temperature of 220 ℃ is the most reasonable choice for the test steel provides a better plasticity.