针对6 mm厚低合金高强钢, 采用激光-MAG复合焊接方法研究了不同工艺参数时的焊缝热影响区冲击性能。结果表明, 焊缝热影响区组织主要由板条马氏体和针状铁素体组成; 随着激光功率的增加, 焊缝热影响区冲击功呈递增趋势, 当激光功率达到2.4 kW时, 其冲击吸收功增幅趋于平缓, 断裂模式以韧性断裂为主; 随着焊接电流的不断增大, 焊缝热影响区冲击功呈先增大后略降低的趋势, 当焊接电流为240 A时, 焊缝热影响区具有最佳冲击性能, 冲击断口具有明显的韧性断裂特征; 随着焊接速度的提高, 焊缝热影响区冲击吸收功呈不断增大的趋势; 当焊接速度为0.6 m/min时, 脆性断裂倾向明显, 而当焊接速度达到1.0 m/min时, 以韧性断裂为主。

Laser-MAG hybrid welding is used to weld the low-alloy ultrahigh strength steel of 6 mm thick and the impact performance of the heat affected zone of weld is studied in different process parameters. The results show that the microstructure of the heat affected zone is mainly composed of lath martensite and acicular ferrite. The impact toughness of the heat affected zone shows increasing trend with increasing laser power. When the laser power is 2.4 kW, the amplification of the impact absorbing energy shows leveling off and the fracture mode is mainly ductile fracture. The impact toughness of the heat affected zone shows the trend of a first increase and then slight decrease with adding welding current continually. When the welding current is 240 A, the heat affected zone has the best impact performance, and the impact fracture surface has obvious characteristic of ductile fracture. With increasing welding speed, the impact toughness of the heat affected zone shows the trend of increase continually. When the welding speed is 0.6 m/min, the brittle fracture tendency is obvious, and the fracture mode is mainly ductile fracture when it is 1.0 m/min.