脉冲激光填丝焊对镍基合金薄板焊缝成形及微观组织的影响

Effect of Pulsed Laser Welding with Filler Wire on Weld Forming and Microstructures of Thin Nickel-Based Alloy Sheet

为了解决激光自熔焊接时薄板焊缝易产生负余高的问题及满足高装配精度的要求,提出了激光填丝焊接(LWFW)工艺,开展了Hastelloy C-276屏蔽套材料的LWFW实验,研究了工艺参数对焊缝形貌的影响,分析了接头不同区域的显微组织、元素分布及显微硬度特征。结果表明,运用LWFW可以获得上下表面正余高可控的焊接接头,在优化工艺参数条件下可获得上下余高、接触角基本一致的焊缝形貌。焊缝晶粒细化明显,母材与熔化线交界处无明显热影响区,焊缝不同熔化区域元素分布均匀,没有明显的元素宏观偏析,但柱状枝晶区Mo元素存在显微偏析。接头不同熔化区域显微硬度分布均匀,硬度值与母材的基本相当。

The process of laser welding with filler wire （LWFW） is presented to solve the problem of negative reinforcement of thin sheet weld seam, and to satisfy the requirement of high precision assembly in laser self-fusing welding. LWFW experiment about Hastelloy C-276 shielding materials is carried out, and the effects of process parameters on the weld forming are studied. The microstructures, element distribution and micro-hardness of weld joints in different zones are analyzed. The results indicate that the weld joints with controllable positive reinforcements on both top and bottom surfaces by using LWFW can be obtained, and the weld appearance with uniform reinforcements and contact angles on upper and lower surface is available under the optimized process parameters conditions. Obvious grain refinement in weld joint and no obvious heat-affected zone at the junction of base metal and fusion line are observed. The element distribution of weld is uniform in different melting zones, and macro segregation is not found, but micro segregation of Mo in columnar dendrite zone is significant. The micro- hardness of weld joint is well-distributed in different regions and the value is basically equivalent to that of base metal.