激光增材修复K465高温合金裂纹控制研究

Study on the crack control of laser additive repaired K465 superalloy

摘要:

采用激光增材技术修复了损坏的K465镍基高温合金航空发动机涡轮叶片，研究了激光增材修复K465高温合金的裂纹特征，分析了开裂机理，并采取有效措施实现了裂纹控制。结果表明：激光增材修复K465合金的裂纹产生于热影响区，并沿晶界扩展到修复区中，为液化裂纹；热影响区晶界上的连续液膜来源于晶界上大尺寸γ′相的液化，且晶界液化过程中有γ-γ′ 共晶出现；利用Ansys软件进行应力场模拟的结果显示，基材及熔池之间存在较大热应力；通过同步预热基材，并采用优化的激光工艺参数，实现了K465高温合金单道多层结构的无裂纹激光增材修复。

Abstract:

Laser additive repairing technique was performed to repair the damaged aeroengine turbine blades made of K465 nickel-based superalloy. The cracks characteristics and cracking mechanism of the laser additive repaired K465 superalloy were investigated. The cracks were eliminated successfully by taking some effective measures. The results showed that the cracks originated from the heat affected zone of the laser additive repaired specimens, and extended to the repaired zone along the grain boundaries. The continuous liquid film was derived from the liquation of larger γ′ particles at the grain boundaries and γ-γ′ eutectics appeared during grain boundary liquation. Stress field simulation results obtained using the Ansys software demonstrated the existence of large thermal stresses at the zone between the substrate and the molten pool. Through preheating the substrates synchronously and adopting the optimized processing parameters, the laser additive repaired specimens with the structure of single track and multi layers without any cracks were obtained.