新型低熔镍基钎料钎焊接头的微观组织及力学性能OA

To solve the problem that the brazing temperature of existing filler metals for joining the superalloy GH4169 exceeds its δ phase solid solution temperature,which leads to the dissolution of the δ phase during brazing and consequently degrades the high-temperature performance of the alloy,this work conducts a study on a novel low-temperature Ni-based brazing filler for GH4169 and optimizes the brazing process.The brazing temperature is set at 980℃,which is comparable to the solid solution temperature of the alloy,in order to achieve a good match between brazing and heat treatment temperatures.Based on the binary phase diagrams,with Pd as the primary melting point depressant and B and Si as the secondary melting point depressants,a novel Ni-based brazing filler of 36Pd-10Cr-3B-1Si-Ni is configured and smelted.The melting point,wettability,and weldability of the novel filler on GH4169-GH536 butt joints are investigated.The results show that the solidus and liquidus temperatures of the novel filler are in the range of 828.82-961.43℃,and the wetting angle is 7.8° at 980℃for 15 min,demonstrating excellent wettability,thereby optimizing the brazing process parameters.Under the process conditions of 980℃for 60 min and a joint clearance-free assembly,the maximum room-temperature tensile strength of the brazed joint reaches 586 MPa,which exceeds that of the conventional BNi-2 brazing filler;the high-temperature creep rupture performance at high temperature exceeds 10 h,and the joint is free of obvious defects.Therefore,the novel low-melting Ni-based brazing filler of 36Pd-10Cr-3B-1Si-Ni can be used to achieve effective brazing of GH4169 while preserving its original microstructure and properties.