2017 年 58 巻 7 号 p. 1042-1048
The effects of particle surface contamination and of the prior particle boundary on the microstructure and mechanical properties of hot-isostatic-pressed IN718 alloy were investigated in this study. A thermal-plasma-droplet-refining technique was conducted to reduce the surface contamination; i.e., oxygen and carbon contents in the gas-atomized IN718 powder. The tensile ductility of hot-isostatic-pressed materials was comparable to those of conventionally wrought materials at room temperature and at 650℃. At 650℃, the hot-isostatic-pressed and heat-treated specimens exhibited worse ductility than the conventionally wrought specimen because of the increased number of brittle precipitates, such as oxides, oxy-carbides and δ phases in the heat-treated specimens. The process of crack nucleation and propagation along the prior particle boundary will take place more easily at high temperatures.
