低焊接裂纹敏感性高强钢的奥氏体动态连续冷却转变行为研究  

Research on the transformation behavior of low welding crack sensitivity high-strength steel plates

作　　者：张君 姚连登[1] 赵小婷[1] ZHANG Jun;YAO Liandeng;ZHAO Xiaoting(Research Institute,Baoshan Iron&Steel Co.,Ltd.,Shanghai 201999,China)

机构地区：[1]宝山钢铁股份有限公司中央研究院,上海201999

出　　处：《宝钢技术》2020年第5期20-23,共4页Baosteel Technology

摘　　要：为研究低焊接裂纹敏感性高强钢Q690在不同冷却速率下的组织转变行为,在Gleeble 3800热模拟机上对Q690钢在不同冷却速率下的膨胀曲线进行测试,确定相变点,并结合显微组织,绘制出该钢种的连续冷却转变曲线。研究表明:随着冷却速度的提高,该钢种的组织变化差异较大。在冷却速率为0.1~0.5 K/s时,钢中主要是铁素体+珠光体,随着冷却速率的增大,组织显著细化,硬度也随之升高;当冷却速率提高到1 K/s后,组织进一步细化,同时钢中开始出现贝氏体转变;当冷却速率达到10 K/s以上时,多边形铁素体形貌基本消失,基体组织主要以贝氏体为主,同时开始出现马氏体。随着冷却速率的继续增大,马氏体含量增加,钢的硬度也逐渐升高;当冷却速率达到30 K/s时,基本呈现出全马氏体组织。In order to study the continuous cooling transformation behavior of low welding crack sensitivity high-strength steel,the dilatometric curves of Q690 steel in different cooling rates have been tested by Gleeble 3800.The CCT diagrams of Q690 steel was constructed through the transformation temperatures determined by dilatometric curves and the corresponding microstructure in different cooling rates.The results showed that microstructure of Q690 steel significantly changed with the increase of cooling rate.The matrix of steel is ferrite and pearlite while the cooling rate between 0.1~0.5 K/s.With increasing cooling rate,the microstructure was significantly refined and the Vickers hardness of steel increased.When the cooling rate reached 1 K/s,the microstructure of steel was further refined and bainite transformation appeared.Polygonal ferrite almost disappeared in the steel when the cooling rate reached 10 K/s,and the matrix is mainly composed of bainite and a small amount of lath martensite.The faster the cooling rate was,the less ferrite and more martensite were in steel,simultaneously,the Vickers hardness was higher.Until the cooling rate reached 30 K/s,the microstructure of steel almost appeared full martensite matrix.

关 键 词：高强钢 热模拟 连续冷却转变 组织性能 

分 类 号：TG142.41[一般工业技术—材料科学与工程]