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采用双相区再加热-淬火-碳配分(IQ&P)工艺,研究了双相区不同等温时间下低碳钢中元素配分行为,并分析其对组织形貌、残余奥氏体及力学性能的影响。结果表明:在IQ&P工艺中,在750℃随等温时间的延长,Mn元素向逆转奥氏体内富集现象逐渐明显,等温时间超过300s后,C元素在两相之间的配分效果不随时间的延长而改变;在750℃等温处理过程中,原奥氏体晶界生成块状逆转奥氏体,马氏体板条界间生成针状逆转奥氏体;随等温时间的延长,钢的最终组织中针状铁素体体积分数不断减小,而块状及针状马氏体体积分数不断增大,同样残余奥氏体体积分数也不断增大;在C、Mn元素的综合作用下,钢的抗拉强度不断增大,断后伸长率先减小而后增大,等温1800s时,钢的强塑积达到最大值21GPa%。
The dual - phase zone reheat - quenching - carbon partitioning (IQ & P) process was used to study the elemental partitioning behavior in low carbon steel with different isothermal time in two - phase zone. The effects of different elements on microstructure, retained austenite and mechanical properties . The results show that in the process of IQ & P, the enrichment of Mn in the reversed austenite becomes obvious with the increase of isothermal time at 750 ℃. When the isothermal time exceeds 300s, the partitioning effect of C between the two phases does not change with time Prolonged and changed; in the isothermal treatment at 750 ℃, the original austenite grain boundaries produce massive reverse austenite, martensitic lath interdependencies generate needle-like austenite; with the extension of the isothermal time, the final steel The volume fraction of acicular ferrite decreased continuously, while the volume fraction of massive and acicular martensite increased continuously, and the volume fraction of retained austenite also increased continuously. Under the combined effect of C and Mn, The tensile strength of steel increases continuously, the elongation at break decreases first and then increases. When the isothermal temperature is 1800s, the maximum ductility of steel reaches 21 GPa%.