Effect of heat input on microstructure and mechanical properties of IC10 Ni3Al-based superalloy electron beam welding joint

Abstract

IC10 single crystal Ni3Al-based superalloy is an important material for manufacturing turbine blades owing to its excellent high-temperature performance. However, the heat input of electron beam welding would extremely influence on microstructure and mechanical properties of IC10 superalloy in engineering applications. The microstructure of the weld can be transformed from single crystal to poly crystal after welding, where its morphology was observed with equiaxed grains in both sides near fusion line and dendrites in the center area. With the heat input decreased in the weld, the refinement of grain size and the number of LAGB lead to the microhardness increased, but the number and proportion of HAGB reduced which to cased the tensile strength deteriorated. The average value of the microhardness in weldment is up to 430 HV, while the tensile strength is 720 MPa. Moreover, the liquid film of low melting point eutectic phases was prone to crack under the high intergranular stress. Due to the refinement of grain size, the decreasing number of HAGB and the enhancement of local grain orientation, the crack sensitivity reduced with the decreasing heat input.