(南昌航空大学 航空制造与工程学院，南昌 330063)
摘 要: 对GH3044高温合金进行光纤激光自熔焊对接实验，结合OM、SEM、EDS、XRD和预拉伸变形等分析方法研究焊接接头的焊缝形貌、组织变化特征和力学性能，讨论焊缝金属快速凝固过程中的相变及元素偏析。结果表明：热输入的增加会导致熔化的金属量增加，熔池的Marangoni对流效应更明显；焊缝金属上部和下部区域为粗大的柱状晶，中部区域为尺寸较小的柱状晶，熔合线靠近焊缝附近区域为细小树枝晶，热输入较小时，焊缝中心区域有等轴晶生成；焊缝组织主要为γ相、共晶(γ+M6C)相，EDS分析表明合金元素的微观偏析较弱；靠近熔合线的热影响区组织变化较小，但焊缝、热影响区的硬度均高于母材的；随着热输入的减小，焊接接头的硬度、抗拉强度逐渐增大，抗拉强度最大为865 MPa，伸长率为43%。
关键字: GH3044高温合金；激光焊接；凝固路径；显微组织；变形均匀性
（School of Aeronautical Manufacturing Engineering, Nanchang Hangkong University, Nanchang 330063, China）
Abstract:GH3044 superalloy was welded by the fiber laser. The weld morphology, microstructure, mechanical properties and the solidification process were investigated. The results show that with the increase of heat input, the area of the cross section of the weld increases gradually. It can also be seen that the upper and lower welds are larger columnar crystals. The columnar crystal size is smaller in the middle of the weld, and the area near the fusion line is fine dendrite. Furthermore there are equiaxed grains in the center of the weld when the heat input is reduced. It is also found that the microstructure constitution of the weld is mainly γ phase, eutectic (γ+M6C) phase. EDS analysis shows that the microsegregation of the alloy elements is weak. The microstructure of the heat affected zone near the fusion line is small, but the hardness of the weld and heat affected zone is higher than that of the parent material and the joint. With the decrease of heat input, the hardness and tensile strength of the welded joint increase gradually, the tensile strength is 865 MPa, and the elongation is 43%.
Key words: GH3044 superalloy; laser welding; solidification process; microstructure; mechanical properties
