低碳硅锰钢I&Q&P处理中C,Mn元素配分综合作用

Comprehensive Effect of C,Mn Partitioning Behavior on Retained Austenite of Low Carbon Si-Mn Steel in I&Q&P Process

采用EMPA,SEM和XRD等手段,研究低碳硅锰钢在双相区保温淬火(I&Q)、双相区保温+奥氏体化+盐浴配分(I&Q&P)和奥氏体化+盐浴配分(Q&P)工艺中的C,Mn元素配分行为及对残余奥氏体的综合作用。结果表明:经I&Q工艺处理后,得到马氏体、铁素体加少量残余奥氏体混合组织,C,Mn在马氏体中出现了富集,并且C富集程度高于Mn;经I&Q&P工艺处理后,C,Mn在板条马氏体中呈现不均匀分布,C的局部富集现象更明显,按C,Mn含量的不同,马氏体可分为"高C高Mn"、"高C低Mn"和"低C低Mn"3种;相比较Q&P工艺中只有C配分作用稳定残余奥氏体,I&Q&P工艺在C,Mn配分综合作用下,能得到更多的残余奥氏体。

Low carbon Si-Mn steel was processed through the processes of intercritical annealing, quenching （I＆Q）, or the intercritical annealing, subsequent austenitizing, then quenching partition （I＆Q＆P） and the austenitizing, quenching partition （Q＆P）. The C, Mn partitioning behavior and their comprehensive effect on retained austenite were studied by means of electron microprobe analysis （EMPA）, field emission scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that the microstructure of low carbon Si-Mn steel is composed of martensite, ferrite and some retained austenite after treated by I＆Q process. C, Mn in martensite of low carbon Si-Mn steel is enriched, and C enrichment level is higher than Mn level. After treated by I＆Q＆P process, C, Mn of steel exhibits nonuniform distribution in lath martensite, and the local enrichment of C is more obvious. The martensite can be divided into three forms of ＂high C high Mn＂, ＂high C low Mn＂ and ＂low C low Mn＂ according to the different C and Mn contents. The content of retained austenite of the steel treated by I＆Q＆P process is higher under the comprehensive effect of C, Mn partitioning than that of Q＆P process which is stabilized only by C partitioning.