Preparation of MIM213 turbine wheel with hollow internal structure

Abstract

Abstract Turbine wheels fabricated by conventional ingot metallurgy suffer casting defects and compositional segregation problems, and their mechanical properties can't be fully developed. This article presents the preparation of MIM213 turbine wheels through metal injection molding in conjunction with hot isostatic pressing. The filling stages of the turbine wheel were investigated by simulation and experimental short shots, and the microstructure and mechanical properties of MIM213 superalloy were examined. It is shown that MIM is suitable for the near-net shape forming of turbine wheel with hollow internal structure and complex blade geometry. Compared with the turbine wheel with solid core structure, the turbine wheel with hollow internal structure has relatively smaller proportion of high temperature region during injection molding, resulting in smaller shrinkage stress and the elimination of shrinkage voids. The relative density of MIM213 superalloy sintered in Ar atmosphere reaches 96.6%. A high volume fraction (31%) of spherical γ′ phase with average particle size of 124 nm, discrete secondary grain boundary borides and internally precipitated MC carbides are formed in austenite matrix. The tensile properties of MIM213 superalloy are higher than that of the equivalent cast K213 superalloy.