层间温度对16MND5钢厚壁构件焊接HAZ冷裂纹及微观组织的影响  

Influence of interpass temperature on the HAZ cold crack and microstructure of thick wall 16MND5 steel structure

作　　者：郭时玲 吴新丽 李恩 邹杰 江国焱 GUO Shiling;WU Xinli;LI En;ZOU Jie;JIANG Guoyan(Dongfang Electric(Guangzhou) Heavy Machinery Co.,Ltd.,Guangzhou 511455,China)

机构地区：[1]东方电气(广州)重型机器有限公司,广东广州511455

出　　处：《电焊机》2019年第4期300-306,共7页Electric Welding Machine

摘　　要：层间温度的选择对低合金钢的焊接质量有决定性作用,尤其是在多层多道焊缝中,各层道焊缝热循环交互影响,组织相变过程极为复杂。系统研究多层多道焊的层间温度对16MND5低合金高强钢HAZ的微观组织和冷裂纹的影响,共设置了4种层间温度,分别为室温、125℃、250℃和400℃。试验结果表明,仅在层间温度为室温时HAZ的粗晶区(CGHAZ)出现冷裂纹,且对应的CGHAZ硬度最高(可达400 HV)。4种层间温度对应的CGHAZ基体组织分别为未完全回火的马氏体、回火马氏体、回火马氏体与下贝氏体的混合组织、粒状贝氏体;除层间温度为室温外,其他3种层间温度得到的CGHAZ,均在靠近熔合线位置出现了魏氏组织,尤其以250℃时居多。综合考虑接头的硬度、微观组织和断裂情况,认为预热温度设置为125～250℃最为合适。The interpass temperature plays a decisive role in the welding quality of high strength low alloy steel. Especially for multi-layer multi-pass welds,the thermal cycle of weld interacts with each other,and the phase transformation is extremely complex. The effect of interpass temperature on the microstructure and cold crack of HAZ of high strength low alloy steel 16MND5 is systematically studied. The experiments are carried out at the room temperature of 125 ℃,250 ℃ and 400 ℃ respectively. The result show that cold cracks occur only in the coarse grained zone of HAZ (CGHAZ) at room temperature,and the corresponding hardness of CGHAZ is the highest (up to 400 HV). The CGHAZ matrix structures corresponding to the four interlayer temperatures are incompletely tempered martensite,tempered martensite,tempered martensite and lower bainite,and granular bainite respectively. In addition,the widmanstatten appears near the fusion line in CGHAZ obtained from all the interpass temperatures except room temperature,especially at 250 ℃. The preheating temperature of 125~250 ℃ is regarded as the most suitable according to the hardness,microstructure and fracture of welded joints.

关 键 词：低合金高强钢 冷裂纹 层间温度 显微硬度 魏氏组织. 

分 类 号：TG40[金属学及工艺—焊接]