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以低碳Si-Mn钢为研究对象,采用双相区保温-淬火(IQ)工艺研究预先Mn配分行为,并对其配分现象进行表征,采用淬火-配分(Q&P)及双相区保温-奥氏体化-淬火-配分(I&Q&P)热处理工艺,探讨了预先Mn配分处理对低碳高强Q&P处理钢中C配分和残余奥氏体及力学性能的影响.结果表明,实验钢在双相区保温过程中C,Mn不断向奥氏体内扩散,淬火处理后C,Mn在马氏体(原双相区奥氏体)内呈现明显的富集现象;实验钢经I&Q&P工艺处理后,室温组织中Mn富集现象依然很明显,C在马氏体板条间富集;随着C配分时间的延长,实验钢抗拉强度不断减小,延伸率均呈先增加后降低趋势,在C配分时间为90 s时,I&Q&P工艺下钢的强塑积达到23478 MPa·%;I&Q&P工艺中预先Mn配分处理,使得实验钢在一次淬火时保留更多的奥氏体,随后C配分促使更多的C原子扩散到这些奥氏体中,从而二次淬火至室温获得更多残余奥氏体.I&Q&P工艺中C,Mn的综合作用稳定的残余奥氏体体积分数比相同条件下Q&P工艺中C配分稳定的残余奥氏体体积分数最大增多2.4%左右.
Taking low carbon Si-Mn steel as the research object, the pre-Mn fractionation behavior was studied by the dual-phase heat-quenching (IQ) process. The quenching-partitioning (Q & P) The effects of pre-Mn fractionation on C content, retained austenite and mechanical properties in low carbon and high strength Q & P treated steels were discussed. The results show that the experimental steels are insulated in the two-phase zone During the process, C and Mn continuously diffused into the austenite. After quenching, C and Mn were obviously enriched in the martensite (original dual-phase zone austenite). After the experimental steels were treated by I & Q & P process, In Mn enrichment phenomenon is still obvious, C in the martensite lath enrichment; with the C with the extension of time, the experimental steel tensile strength decreases, the elongation were increased first and then decreased, C with points When the time is 90 s, the strength of steel in I & Q & P process reaches 23478 MPa ·%. In the I & Q & P process, Mn pre-treatment is carried out so that the experimental steel retains more austenite during the first quenching and then the C content promotes more C atoms diffuse into these austenite, so secondary quenching to room temperature for more residual austenite.I & Q & P The volume fraction of retained austenite with the combined effect of C and Mn in the process is about 2.4% larger than the volume fraction of retained austenite with stable C component in Q & P process under the same conditions.