Microstructure and mechanical properties of Inconel713C Ni3Al-based superalloy joint welded by electron beam feeding wire welding technology

Owing to its excellent performance at high temperatures, the Inconel713C casting superalloy has been exten-sively used as a functional and structural material in the aviation and energy industries. Many Inconel713C superalloy components have to be manufactured by welding technologies, but joint cracks are often induced by fusion welding, deteriorating the performance of the components. Here, a modified Inconel713C casting su-peralloy joint without cracks was obtained using electron beam feeding wire welding with the Inconel718 alloy as the filler. The tensile strength of the joint reached 1070 MPa, exceeding that of the base metal (722 MPa) by 32.5 %. Smaller-size grains, smaller gamma ' phase, and larger gamma ' phase volume fraction were obtained by controlling the chemical composition and heat input of the welds. The microstructure of the fusion zone comprised den-drites, including a large number of gamma ' phases (approximate size, 18 nm) and carbides (approximate size, 2 mu m) distributed in the gamma matrix. The microhardness of the fusion zone (approximately 420 HV) exceeded that of the base metal (approximately 370 HV), with no obvious softening in the heat-affected zone.