Research on Resistance Spot Welding Positioning Technology for T-shaped Parts Between Thin Wall of Honeycomb and Substrate in Aeronautic Engine

To address the positioning welding challenge for the T-shaped structure connection (Thickness ratio is 1:50) between GH3536 honeycomb and K423A substrate in aircraft engines, an inverter resistance spot welding machine with a power of 55 kVA and a frequency of 4 kHz was utilized. A pair of asymmetric electrodes of pure copper braided wire wrapped with pure copper blocks (honeycomb side)/chromium-zirconium copper cylinders (substrate side) were designed for increasing the effective conductive area of spot welding and supressing the current skin effect. Under the optimal welding process parameters of I=1.75 kA, t=65 ms, and F=27 N, the metallurgical connection between the honeycomb and substrate was achieved, with a high degree of surface flatness of the honeycomb and no bending of the core wall. Corresponding SEM images and EDS spectra revealed significant changes in the content of Ni, Ti, and Cr elements at the optimal positioning welding, with a fusion thickness of ca. 3 μm. The content of Mo element first decreased and then increased in the joint. And Mo-containing M₆C and M₂₃C₆ carbides were created in the weld zone, which have high strength under high-temperature service environment, meeting the high-quality positioning requirements for the honeycomb/substrate connection.