Incoloy alloy 800 is a superalloy particularly suited to aggressive corrosive environments. Both weld quality and productivity may be enhanced when joining parts by laser beam welding (LBW). The current paper describes joining of Incoloy alloy 800 plates (4 mm thickness) by laser welding (Nd:YAG). The laser scan speed was varied between 0.5 and 2 m/min for a constant power input (laser). The evolution of the microstructure was investigated utilizing both traditional and advanced microscopic techniques. The results indicated an hourglass shaped fusion zone which was slightly larger on the top surface. Elongated columnar but fine equiaxed dendrites were present in the fusion zone. Significant phase transformation occurred because of a higher cooling rate that is typical with laser welding. An uneven and planar distribution of dislocations associated with subgrain boundaries were observed adjacent to Laves phases. The formation of Laves phases at the lowest scanning speeds reduced the mechanical properties. Mechanical testing showed that the joints failed in the weld zone at the lower scanning speeds because of the presence of the Laves phases. Ductile fracture was demonstrated at the higher scanning speeds whereas brittle fracture occurred at the lower scanning speeds.

Incoloy合金800是一种特别适合于腐蚀性腐蚀环境的高温合金。通过激光束焊接（LBW）连接零件时，可以提高焊接质量和生产率。本文描述了通过激光焊接（Nd：YAG）连接Incoloy合金800板（厚度为4 mm）。对于恒定功率输入（激光），激光扫描速度在0.5和2 m / min之间变化。利用传统和先进的微观技术研究了微观结构的演变。结果表明沙漏形融合区在顶表面稍大。融合区存在细长的柱状但等轴细的枝晶。由于激光焊接具有较高的冷却速度，因此发生了明显的相变。在Laves相附近观察到与亚晶粒边界相关的位错的不均匀和平面分布。最低扫描速度下的拉夫斯相的形成降低了机械性能。机械测试表明，由于存在Laves相，因此在较低的扫描速度下，焊接区的接头失效。在较高的扫描速度下显示了韧性断裂，而在较低的扫描速度下出现了脆性断裂。