为了研究激光焊接工艺对K418与0Cr18Ni9异种金属焊接接头性能的影响,采用金相显微镜对焊缝的金相组织和形貌进行了分析,评价了焊缝及周边的硬度和强度。结果表明,在激光焊接K418高温合金与0Cr18Ni9时由于母材热物性参量存在较大的差异,为保证焊缝质量,激光光斑应偏向0Cr18Ni9合金一侧; 为了防止热裂纹和液化裂纹的产生,应该尽量延长熔池凝固时间同时减少热影响的热输入; 当保护气体流量为12L/min时,对焊缝的保护效果最好,与Ar2相比N2能有效减少焊缝中气孔的含量,但也会降低焊缝性能; 焊缝的硬度值位于两母材硬度之间,焊接接头的强度约为母材的89%。采用合适的激光焊接工艺可以实现K418合金与0Cr18Ni9较好的焊接效果。

In order to study effect of laser welding on the properties of dissimilar metal welding joints of K418 and 0Cr18Ni9, microstructure and morphology of the weld were analyzed by using a metallographic microscope. The hardness and strength of weld seams and their surrounding area were evaluated. The results show that when laser welding of K418 superalloy and 0Cr18Ni9, there are great differences in thermal parameters of the base metal. In order to guarantee weld quality, laser spot should be biased on the side of 0Cr18Ni9 alloy. In order to prevent thermal cracks and liquation cracks, coagulation time of the melted pool should be prolonged as far as possible and heat input with heat effect should be reduced simultaneously. The protection of weld seam is the best when protection gas flow rate is 12L/min. Compared with Ar2, N2 can effectively reduce the porosity in weld seams, and it also reduces the weld performance. The hardness of the weld is between the hardness of two base materials. The strength of the weld joint is about 89% of that of the base metal. Good welding quality of K418 alloy and 0Cr18Ni9 can be achieved by adopting suitable laser welding process.