正火钢Q370qE焊接接头热影响区组织及冲击韧性研究

Study on microstructure and impact toughness of HAZ on welded joints of normalized steel Q370qE

针对两种不同成分的正火钢Q370qE,利用EPMA测定焊接接头熔合线附近的元素分布,采用金相显微镜观察热影响区组织,利用Pro Imaging软件测定组织占比及晶粒度大小,分析母材合金元素和焊接工艺对焊接接头组织及性能的影响机理.结果表明:含Ni量较高的Q370qE在焊接过程中,熔合区附近Cu、Ni、Nb和V元素迁移,细化了铁素体晶粒;C曲线右移,生成细小均匀分布的粒状贝氏体,从而提高了热影响区的低温冲击韧性.

In this paper,normalized steel Q370qE with two different components are studied.The element distribution in the fusion zone(FZ)of welded joints is measured by EPMA.The structure of the HAZ is observed by metallographic microscope.The tissue proportion and grain size are calculated by Pro Imaging software.The influence mechanism of parent metal alloy elements and welding process on the structure and performance of welded joints is analyzed.The results show that during welding process of Q370qE with high Ni content,the migrations of Cu,Ni,Nb and V elements in the FZ of welded joints refine the ferrite grains.The right shift of C curve promotes the formation and uniform distribution of granular bainite in the coarse crystal zone,and these improve the low temperature impact toughness.