CHARACTERIZATION AND SIMULATION OF Ni-BASED SUPERALLOY POWDER FEEDSTOCK FOR POWDER INJECTION MOLDING

Abstract

Powder injection molding, a powder-based net-shape technology, has promise as a process for the mass production of superalloy turbocharger blades. A Ni-based superalloy feedstock was characterized and simulated to predict possible defects and to find the optimum process conditions. The critical powder solids loading was found to be 68%, where the mixing torque increased abruptly. The feedstock showed shear thinning behavior at 150 degrees C, 160 degrees C, and 170 degrees C, where the shear viscosity showed the lowest value at the highest temperature. A high shear-rate region was found on the turbine blade surface, and proper gate location and injection speed profile were suggested to improve molding in this region. An optimization study was carried out using the Taguchi method. This computational study aims to improve the quality of superalloy powder injection molded components by providing information regarding possible defects prior to processing.