针对镍基高温合金激光熔覆过程中覆层极易产生裂纹的问题, 在高温合金K438基体上激光熔覆Inconel 738合金粉, 研究了熔覆层的开裂机理以及裂纹控制方法。裂纹由靠近基体端的过渡层产生并扩展到熔覆层, 具有典型的沿晶特征, 裂纹的形成主要与熔覆层中的热输入和低熔共晶相有关。从减少激光熔覆层中的低熔共晶相出发, 通过优化激光熔覆工艺参数、添加适量Y2O3以及对基体进行同步冷却, 可在一定程度上减少甚至避免熔覆层裂纹的产生。

During the laser cladding process of Ni-base superalloy, cracks are easily prone to form in the transition region between the cladded layer and substrate and the surface. Inconel 738 powder was cladded on the K438 superalloy by high power laser in this paper. The cracking mechanism and the methods of crack control for Inconel 738 laser cladding layer were investigated. The crack initiates from the transition region between the cladded layer and substrate and spreads into laser cladding layer, which is mainly caused by high heat input and low-melting eutectic phases. The results show that optimizing processing parameters, adding proper content of Y2O3, and cooling the substrate at the same time of laser cladding can control the cracking tendency in some extend, decrease and even relief the cracks.