Effect of holding time on interfacial evolution and mechanical strength of wide-gap brazed K417G superalloy joints

Abstract

K417G superalloy is widely applied in gas turbine components such as blades, vanes, and nozzles. In this study, wide-gap brazing of K417G superalloy is investigated using BNi-5 filler alloy. The brazing experiment is conducted at 1150 °C for different holding times with the fixed gap of 0.2 mm. For the joints brazed for 15 min, the brazing seam mainly consists of γ/γ’ phase, Ni₂Si and TiC phase. The average tensile strength tested at 950 °C is 401 MPa. As the holding time increased, the excessive element diffusion phenomenon is observed. Hence, Ni₂Si intermetallic phases gradually become embedded in the additive alloy particles. The interfacial evolution and fracture behavior are discussed.