金属粉末射出成形により作製されたNi基耐熱合金IN713の結晶粒成長促進技術の開発

抄録

High temperature strength is one of the critical technical issues to apply metal injection molding (MIM) to Nickel-based superalloy IN713. In this study, through investigating microstructure and high temperature strength of IN713-MIM materials in detail, we developed the technique to promote grain growth. In the experiments using IN713C-MIM materials, the high temperature tensile strength and the creep strength were remarkably inferior to the castings. The creep deformation mechanism of IN713C-MIM materials is revealed that grain boundary diffusion creep was dominant as the stress exponent was determined as n = 2.72. Therefore, we found out that it was important to reduce the amount of grain boundary by promoting grain growth. In the examinations aiming to reduce carbides on grain boundary, which inhibited grain boundary migration, the carbon content of IN713LC-MIM-sintered material could be suppressed to C = 0.05%. Subsequently, when IN713LC-MIM-HIP-ed material was subjected to additional heat treatment at 1280°C for 12 hr, significant grain growth was observed.