采用碟片激光器对5 mm厚紫铜进行激光焊接, 研究了激光焊接过程中的激光功率对焊缝成形的影响, 并研究焊接接头组织特征及力学性能。结果表明, 在激光功率4.5～9.5 kW范围内, 焊缝熔深与激光功率几乎呈线性关系; 高功率可显著减少焊接过程的飞溅及表面孔洞, 未焊透的焊缝飞溅及表面孔洞多于焊透的焊缝。焊透的焊缝横截面形貌为I型形貌, 焊缝横截面左右两侧显微组织为水平方向的柱状晶, 越靠近焊缝中间的柱状晶长度越短, 而焊缝中间显微组织为平行于厚度方向的柱状晶。接头拉伸断裂于焊缝处, 焊接接头的抗拉强度和延伸率较母材发生显著降低, 焊接接头的拉伸强度为母材的77.3%, 延伸率为母材的41.8%。

A disc laser was used to weld copper with 5 mm thickness. The effect of laser power on weld formation during laser welding was studied and microstructure and mechanical properties of the weld joints were investigated. The results show that a nearly linear relationship between weld penetration and laser power within the range of 4.5～9.5 kW. High power can effectively reduce the spatter and surface cavity in the welding process, and the spatter and surface cavity of the un-penetrated welds is more than that of the fully penetrated welds. The cross-section morphology of the fully penetrated welds is I shape. The microstructure of the weld have horizontal columnar crystal on the left and right sides of the cross-section, and length of the columnar crystal near the middle of the weld is shorter, and the middle microstructure of the weld is a columnar crystal parallel to the thickness direction. The weld joints fracture at the weld seam, and the tensile strength and elongation of the welded joints decrease significantly compared to the base metal. The tensile strength of the welded joints can reach 77.3% of that of the base metal. The elongation can reach 41.8% of that of the base metal.