Laser welding of Nb-1% Zr-0.1% C was attempted in butt-welding configuration using top and bottom sided inert gas shielding. The precautionary measure during welding was to limit the reactivity of niobium alloy in ambient atmosphere. The ranges of input parameters, that is, laser power (P), welding speed (V) and beam diameter (D) for full penetration welding were attempted by carrying out bead-on-plate (BOP) experiments. The selection of the combination of process parameters was such that the formed weld area could be minimized without hampering the depth of penetration. Bead-geometry, hardness and tensile strength were quantified to study the influence of input process parameters during laser welding. Base metal had an average hardness of 108 VHN and the average hardness of fusion zone (FZ) was found to lie between 278 and 546 VHN. The steeper increment in microhardness value of the FZ could be due to the grain refinement, dissolution of precipitates and formation of brittle intermetallic phases of carbide and oxides, which were evident by the result of energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) phase analysis. The weld joint that failed in the weld zone exhibited the brittle failure, and ductile mode was achieved in the joint, where failure occurs at base metal. The range of elongation in laser welded joints varied in between 1.97 and 5.73 mm. The reduction of tensile strength and ductility of the joints could be due to marginal enhancement of microhardness and increment of brittle phase density in fusion zone, as were evident from XRD phase analysis. The main focus of the present work was intended towards the establishment of laser welding as an alternative technique for fabrication of reactive niobium alloy in ambient atmosphere.

Nb-1％Zr-0.1％C的激光焊接尝试使用顶侧和底侧惰性气体保护层进行对接焊接。焊接时的预防措施是限制铌合金在环境气氛中的反应性。通过进行板焊（BOP）实验，尝试了全熔透焊接的输入参数范围，即激光功率（P），焊接速度（V）和光束直径（D）。工艺参数组合的选择应使所形成的焊接区域最小，而不会影响熔深。对珠的几何形状，硬度和抗拉强度进行了量化，以研究激光焊接过程中输入工艺参数的影响。贱金属的平均硬度为108 VHN，熔合区（FZ）的平均硬度为278至546 VHN。FZ显微硬度值的陡峭增长可能归因于晶粒细化，析出物的溶解以及碳化物和氧化物的脆性金属间相的形成，这可以通过能量色散光谱（EDS）和X射线衍射（ XRD）相分析。在焊接区域中失效的焊接接头表现出脆性失效，并且在接头处实现了延性模式，其中在母材处发生失效。激光焊接接头的延伸范围在1.97和5.73毫米之间变化。从XRD相分析可以明显看出，接头抗拉强度和延展性的降低可能是由于显微硬度的略微提高和熔合区脆性相密度的增加所致。