低碳Si-Mn系DQ&P钢组织演变模拟研究

Simulation Study on Microstructure Evolution of Low Carbon Si-Mn Steel During Direct Quenching and Partitioning

以低碳Si-Mn钢为研究对象,采用直接淬火-配分工艺,研究了不同变形温度和配分时间对组织演变行为的影响.结果表明,Q&P钢典型组织由马氏体、铁素体和少量残余奥氏体组成.其中马氏体呈现板条马氏体、孪晶马氏体等特征.随着配分时间的延长,显微组织呈现回火转变趋势.当变形温度为950℃和880℃时,残余奥氏体体积分数先增加后减少,均在配分150 s时达到最大值,分别为9.1%,10.1%.当变形温度在820℃时,由于先共析铁素体的存在易于获得较多的残余奥氏体,体积分数高达11.9%,并且残余奥氏体中平均碳含量相对较低.

Effects of deformation temperature and partitioning time on microstructure evolution of low carbon Si-Mn steel during direct quenching-partitioning process were investigated. The volume fraction of retained austenite and the carbon concentration in retained austenite were quantitatively studied. The results showed that the typical microstructure of Q＆P steel consists of a small amount of retained austenite, ferrite and martensite containing lath martensite and twin martensite. With increase of the partitioning time, the microstructure shows a tempered transformation tendency. When deformation temperature is 950 t and 880 t,the volume fraction of retained austenite decreases after the first increase and reaches the maximum,9. 1 % ,10. 1 %, respectively at the partitioning time of 150 s. When deformation temperature is 820 t,the volume fraction of retained austenite increases up to 11. 9% because of proeutectoid ferrite. And the carbon concentration in austenite is relatively lower.