通过分析接头的显微组织、拉伸性能、扩孔率及杯突值, 研究了热输入对激光对接接头组织及性能的影响。结果表明, 接头保护效果较好, 焊缝中心显微组织为针状α晶粒＋粗大α晶粒, 热影响区组织为不规则的粗大α晶粒＋少量锯齿状α晶粒, 线能量对晶粒尺寸影响较大; 接头拉伸性能随热输入的提升呈先上升后下降的趋势, 热输入为400 J/cm时, 接头具有最优的拉伸性能; 提高热输入, 接头成形性能逐渐下降, 热输入为300 J/cm时, 接头成形性能最优。

The microstructure, tensile properties, hole expansion ratio and cupping value of joint were analyzed to study the effect of heat input on the microstructure and properties of laser butt joint. The results show that the protection effect of joint is better, the microstructure of the weld center is acicular α grain and coarse α grain, the microstructure of the heat affected zone is irregular coarse α grain and a little jagged α grain, the line energy has a great influence on the grain size. The tensile properties of the joints increase first and then decrease with the increase of heat input. When the heat input is 400 J/cm, the joints have the best tensile properties. When the heat input is increased, the forming property of the joints is gradually reduced, and the joint forming property is optimal when the heat input is 300 J/cm.