355 MPa低合金钢板焊接裂纹的成因分析  

Analysis on the Causes of Welding Cracks in 355 MPa Low Alloy Steel Plate

作　　者：王治中 孙乾 程欣丽 员强鹏 孟倩 陈萌 WANG Zhizhong;SUN Qian;CHENG Xinli;YUAN Qiangpeng;MENG Qian;CHEN Meng(Nanjing Iron and Steel Co.,Ltd.,Nanjing 210035,China;Laiwu Branch of Shandong Iron and Steel Co.,Ltd,Laiwu 271104,China;Laiwu Steel Group Lantian Commercial Vehicle Co.,Ltd.,Jinan 271104,China)

机构地区：[1]南京钢铁股份有限公司,江苏南京210035 [2]山东钢铁股份有限公司莱芜分公司,山东济南271104 [3]莱钢集团蓝天商旅车业有限公司,山东济南71104

出　　处：《山东冶金》2023年第5期36-39,共4页Shandong Metallurgy

摘　　要：针对20 mm厚度355 MPa低合金钢板焊接时出现的焊接裂纹问题,采用成分分析、金相组织检验、夹杂物分析、扫描电镜观察等手段进行检验分析。结果表明,钢板以铁素体+珠光体组织为主,含少量贝氏体,组织细小均匀,晶粒度约9.5级,力学性能满足标准;起裂位置为焊缝热影响区,焊缝宽度约8 mm,裂纹较深且尾部延展,焊缝热影响区以粗大的魏氏组织为主,缝处内存在链状非金属夹杂物。焊接时功率过大,焊缝处金属熔融速度较快,熔池夹杂清理不净而凝固在焊缝,割裂钢板组织连续性,结合焊接热影响区魏氏组织韧塑性差,焊接后下道次校正拉应力作用下,诱发局部开裂,是产生裂纹主原。通过优化焊接功率,缩短母材焊边在高温区的停留时间,控制冷却,减少异常组织,可有效避免该类问题。During welding,in response to the welding crack problem of the 355 MPa low alloy steel plate with 20 mm thickness,methods such as composition analysis,metallographic examination,inclusion analysis,and scanning electron microscopy observation were used for inspection and analysis.The results show that the steel plate is mainly composed of ferrite plus pearlite structure,with a small amount of bainite.The structure is fine and uniform,with a grain size of about grade 9.5,and the mechanical properties meet the standards.The starting point of the crack is the heat affected zone of the weld seam,with a width of about 8 mm.The crack is deep and extends at the tail.The heat affected zone of the weld seam is mainly composed of coarse Weinstein structure,and there are chain shaped non-metallic inclusions in the seam.When welding,the power is too high,the metal melting speed at the weld seam is fast,the inclusion in the molten pool is not cleaned thoroughly and solidifies in the weld seam,cutting the continuity of the steel plate structure.Combined with the poor toughness and plasticity of the Weinstein structure in the welding heat affected zone,local cracking is induced by the next correction of tensile stress after welding,which is the main cause of cracks.By optimizing welding power,shortening the residence time of the base metal weld edge in the high-temperature zone,controlling cooling,and reducing abnormal structures,such problems can be effectively avoided.

关 键 词：355 MPa低合金钢 焊接裂纹 夹杂物 金相组织 魏氏组织 

分 类 号：TG142.1[一般工业技术—材料科学与工程]