非等温碳分配条件下的热轧DQ&P工艺研究

为满足汽车轻量化的发展要求, 先进高强度钢已成为研究热点, 近年来以淬火-分配(Q&P)理念为基础的工艺研究备受关注。本文将Q&P理念引入热轧工艺过程中, 并进行了实验研究, 即采用直接淬火（DQ）工艺结合非等温条件下碳分配处理(碳分配过程在模拟卷取过程中进行)。实验结果表明: 实验钢组织由马氏体、残余奥氏体及少量铁素体组成。当卷取温度为350 ℃时, 实验钢组织中残余奥氏体体积分数较高, 达到11.5%, 同时抗拉强度达到1 370 MPa, 伸长率为14.20%, 强塑积为19.5 GPa·%。进行TEM观察, 发现马氏体板条束之间存在以薄膜状形态分布的残余奥氏体。

Research on hot-rolling DQ&P process under non-isothermal carbon partition

In order to satisfy the requirements of lightweight in the automotive industry, advanced high strength steel has become a hot topic. In recent years, the research based on Q&P concept has been paid extensive attentions. The present work takes Q&P concept into considerations during hot rolling process, combining direct quenching with non-isothermal carbon partition that the partition process will occur during the coiling process. The test results show that martensite , retained austenite and a little ferrite are obtained in the tested steel. When the coiling temperature is at 350 ℃, the microstructure includes a higher fraction of retained austenite reaching 11.5%,and the tested steel exhibits high ultimate tensile strength exceeding 1 375 MPa and fine elongation of 14.2% and TS ×TEL of 19.5 GPa·% .In addition, there is thin film retained austenite presenting in martensite lath when observed by TEM.