采用光纤激光对1.2 mm厚HC420LA钢进行激光焊接, 研究不同焊接速度(1.2, 2.4, 3.6和4.8 m/min)对接头截面形貌、显微组织、硬度和强度的影响。结果表明, 焊接功率一定时, 速度对焊缝截面形状及熔宽影响显著。随着焊速增加, 熔深和熔宽均降低, 焊接接头未出现裂纹和气孔缺陷; 在焊速为2.4 m/min和3.6 m/min时, 焊缝连续且成形较好; HC420LA钢焊缝的显微组织为铁素体、贝氏体和马氏体组织, 随着焊接速度的增加, 马氏体含量增大; 焊接熔合区在较低和较高焊速时, 组织粗大明显; 焊缝和热影响区的硬度均高于母材, 焊接接头无软化现象; 垂直于焊缝方向, 焊接接头拉伸试样均在母材一侧发生断裂, 焊接接头强度稍高于母材。

Fiber laser welding was carried out at different welding speeds on 1.2 mm thick HC420LA steel. The influences of welding speed (1.2, 2.4, 3.6 and 4.8 m/min)on the cross section morphology, microstructure, hardness and strength of the joints were studied. The results show that the welding speed has a significant effect on the shape of the weld section and weld width when the welding power is constant. With the increase of welding speed, the depth and width of the weld decreases, and there is no cracks and porosity defects in the welded joints. When the welding speed are 2.4 m/min and 3.6 m/min, the shape of the weld is continuous and well formed. The microstructure of HC420LA steel weld are ferrite, bainite and martensite. The martensite content increases with the increase of welding speed. The microstructure of welding fusion zone is coarse at lower and higher welding speeds. The hardness of the weld and heat affected zone are higher than that of the base material, and the welded joints are not softened. Perpendicular to the welding direction, the tensile specimens of the welded joints are fractured on the side of the base material, and the strength of the welded joints are slightly higher than that of the base material.