船用E级钢厚板CO2激光多层焊接工艺与组织
Multi-pass Welding Process and Microstructure of Shipbuilding E-class Thick Steels Using CO2 Laser Welding
杨东杰1, 胡连海1， 黄 坚1， 倪慧峰2
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作者单位：（1.上海交通大学 材料科学与工程学院 上海市激光制造与材料改性重点实验室，上海 200240；2.江南造船（集团）有限责任公司，上海 201913）
中文关键字： E级钢； CO2激光多道焊； 微观组织； 显微硬度
英文关键字：E-class steel; CO2 laser multi-pass welding; microstructure; microhardness
中文摘要：根据激光焊接的特点，设计了适用于激光焊接厚船用板的坡口，分别采用纯激光焊和激光-MIG复合焊，用5道焊接实现了24 mm船用厚板的激光焊接。对焊缝的宏观截面检测，发现存在少量的分散气孔，没有裂纹。对焊后的组织和硬度趋势进行了分析，结果表明：焊缝组织主要为板条马氏体和上贝氏体；热影响区的粗晶区以粗大的板条马氏体为主，细晶区以细小的粒状贝氏体和板条马氏体为主；焊缝重叠区域的主要组织为粒状贝氏体和板条马氏体；沿焊缝中心线从上到下硬度的总体趋势是逐渐降低；硬度值在热影响区细晶区达到最大，小于380 HV，满足船用技术要求。
英文摘要： Based on the characteristic of laser welding, a groove of shipbuilding E-class thick steels was designed to meet the requirements of laser welding. A 24 mm thickness plate was welded with five passes using pure laser welding and laser-MIG hybrid welding. No crack was found and there was only a small amount of pores. The microstructure and hardness of laser welded joint were analyzed. The results indicate that the weld microstructure mainly includes lath martensite and upper bainite, the coarse grain region of HAZ mainly includes coarse lath martensite, the fine grain region mainly consists of granular bainite and lath martensite, and the microstructure of the overlapping zone of the weld is mainly composed of granular bainite and lath martensite. The hardness gradually decreases from top to bottom along the weld centre. The hardness in the fine grain region of HAZ reaches its maximum, which is less than 380 HV and can meet the requirement of shipbuilding technology.