Influence of welding sequences on the microstructure and mechanical properties of dual-pass electron beam welded Ti60/V/Cu/GH3128 joints

Abstract

Electron beam welding of Ti60 titanium alloy to GH3128 nickel-base superalloy was realized by using V/Cu composite interlayers, based on the element metallurgical compatibility. The effects of welding sequences on the microstructures and properties of the joints were analyzed. Microstructures and energy spectrum analysis shown that the reaction of Ti and Ni atoms to form brittle intermetallic compounds (IMC) can be effectively prevented by the interlayers. When the electron beam was first focused on the V foil, the copper foil was melted due to the high melting point of vanadium (1890 °C). Continuously distributed CuTi IMCs were produced near the Ti60 side. When the electron beam was first focused on the Cu foil, CuTi IMCs were replaced by the formation of (Ti,V) solid solutions at the interface of Ti60. A joint with a maximum tensile strength of 392 MPa, 49% of that of the GH3218 alloy was obtained. The fracture morphology proved that the fracture type belonged to brittle fracture.