Net-Shape Forming and Mechanical Properties of MIM418 Turbine Wheel

Near-net shape forming of the turbine wheel with a hollow internal structure was realized by adopting the die with side core-pulling mechanism. MIM418 turbine wheel with relative density above 99.5% is obtained by the combination of vacuum sintering and hot isostatic pressing. A high volume fraction (57%) of near cuboidal γ′ phase with average particle size of 0.52 μm is formed in γ matrix. Small amount of discrete carbides with size of 0.2-0.4 μm is distributed uniformly on grain boundaries and within grains. The tensile strength, yield strength, and ductility of MIM418 superalloy reach 1425 MPa, 1004 MPa, and 19.4%, respectively, which are much higher than that of the cast K418 superalloy.