不同原始组织对高强钢板相变行为的影响  

Effect of different original microstructure on phase transformation behavior of high-strength steel plates

作　　者：王堤鹤 庞启航 赵星宇 李维娟[1] 史津铭 WANG Dihe;PANG Qihang;ZHAO Xingyu;LI Weijuan;SHI Jinming(School of Material and Metallurgy,University of Science and Technology Liaoning,Anshan 114051,China)

机构地区：[1]辽宁科技大学材料与冶金学院,辽宁鞍山114051

出　　处：《轧钢》2024年第4期16-23,29,共9页Steel Rolling

基　　金：国家自然科学基金项目(52004122)

摘　　要：近年来,为了实现汽车构件的轻量化,各国在不断探索和开发低成本高强度金属材料。Q&P钢以高强度、高延展性及易焊接性能逐步成为汽车用高强钢的主流产品。研究了基于组织遗传性下原始组织对高强钢在热加工过程中相变行为的影响规律,以实现对实际生产工艺的优化。采用动态热力学模拟试验机、高温激光共聚焦显微镜(CLSM)、Axia Chemi钨灯丝扫描电镜(SEM)等先进实验设备,原位观察了不同原始组织高强钢板奥氏体化和晶粒长大过程,以及冷却过程中的相变行为。实验结果表明:当终冷温度为350、550、680℃时,3种终冷温度下高强钢板的原始组织分别为“马氏体+铁素体”(M+F)、“贝氏体+铁素体”(B+F)和“珠光体+铁素体”(P+F)。综合比较发现,原始组织为“P+F”的高强钢板,其临界奥氏体化温度(Ac1)为647.9℃,与奥氏体晶粒异常长大临界温度相差417℃,奥氏体晶粒的生长方式是晶界迁移与小晶粒合并,奥氏体平均晶粒尺寸为0.66μm;马氏体开始转变温度(Ms)为362℃,因此具有较宽的热加工工艺窗口,利于工业生产Q&P热处理工艺的柔性调控。In recent years,in order to achieve the lightweight of automotive components,countries have continuously explored and developed low-cost high-strength metal materials.Q&P steel has gradually become the mainstream product of automotive high-strength steel with high strength,high ductility and easy weldability.In order to optimize the actual production process,the effect of the original microstructure on the phase transformation behavior of high-strength steel in the process of hot working was investigated.The austenitizing and grain growth of high-strength steel plates with different original microstructure and the phase transition during cooling were observed in situ by dynamic thermodynamic simulation tester,Confocal-Laser-Scanning-Microscopy(CLSM)and Axia Chemi tungsten filament scanning electron microscope(SEM).The results show that when the final cooling temperature is 350℃,550℃and 680℃,the original microstructure of the high-strength steel plate at the three final cooling temperatures is“martensite+ferrite”(M+F),“bainite+ferrite”(B+F)and“pearlite+ferrite”(P+F),respectively.It is found that the critical austenitic temperature(Ac1)of the high-strength steel plate with the original microstructure of“P+F”is 647.9℃,which is 417℃different from the critical temperature of austenite grain abnormal growth.The growth mode of austenite grains is grain boundary migration and small grain merger,and the average austenite grain size is 0.66μm.The martensitic initial transition temperature(Ms)is 362℃,so there is a wide hot processing process window,which is conducive to the flexible control of Q&P heat treatment process in industrial production.

关 键 词：高强钢 原始组织 相变规律 原位观察 P+F组织 轻量化 

分 类 号：TG142.1[一般工业技术—材料科学与工程]