摘要:
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。
Abstract:
Low carbon Si-Mn steel was processed through intercritical insulation-quenching-partition,and effect of quenching temperature on microstructure and mechanical properties of Q&P steel was studied by means of field emission scanning electron microscopy,X-ray diffraction and tensile tests.The results show that quenching temperature at 220℃ generates the best comprehensive mechanical performance where tensile strength is 1 400 MPa,elongation is 13.3%,product of strength and elongation up to 18 620 MPa·%.With the increase of quenching temperature,the tensile strength of experimental steel decreases gradually,the ductility has increased,and lath martensite content reduce,carbide particles increase,there also has been a small amount of massive martensite structure.Intercritical Mn partition complements the lack of carbon partitioning during Q&P process which leads to final retained austenite at room temperature consisting ofa small amount of carbon-rich austenite and Mn-rich residual austenite with carbon partitioning.Quenching at 220℃ provides the experimental steel a good plasticity.
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