Gas turbine blades working under extremely harsh operating conditions are made of superalloys. These superalloys are exposed to various damage mechanisms, which wear them out gradually. Welding is often preferred to repair the damaged components for cost minimization. This study aimed to investigate the effects of flexural load, heat input, and welding speed on the weldability and intergranular liquation cracking of high-chromium Ni-based superalloy. For this purpose, a series of Sigmajig tests designed based on the Taguchi method with L4 array, as well as microstructure investigations and residual stress measurements, were performed. The results showed that the microstructures of heat-affected zones (HAZs) were highly susceptible to cracking during the welding process, and all of these cracks appeared in the HAZ and grew perpendicular to the melting zone along grain boundaries. Flexural load contributed the most substantial impact (82%) on crack propagation compared with the 9.7 and 9.2% impacts of welding speed and welding heat input, respectively. We found that the lowest flexural load, welding speed, and heat input are the best welding parameters to reduce the total crack lengths at the welded area of high-chromium Ni-based superalloy.

在极端苛刻的工作条件下工作的燃气轮机叶片由高温合金制成。这些高温合金会受到各种损坏机制的影响，这些损坏机制会逐渐使它们磨损。为了降低成本，通常首选焊接来修复损坏的组件。本研究旨在研究弯曲载荷，热量输入和焊接速度对高铬镍基高温合金的可焊性和晶间液化开裂的影响。为此，进行了基于Taguchi方法和L4阵列设计的一系列Sigmajig测试，以及微观结构研究和残余应力测量。结果表明，热影响区（HAZs）的微观结构在焊接过程中极易开裂，所有这些裂纹都出现在热影响区中，并沿晶界垂直于熔化区生长。弯曲载荷对裂纹扩展的影响最大（82％），而焊接速度和焊接热量输入的影响分别为9.7％和9.2％。我们发现，最低的弯曲载荷，焊接速度和热量输入是降低高铬Ni基高温合金焊接区域总裂纹长度的最佳焊接参数。