Impurity Removal and Microstructural Analysis of Inconel 718 Refined by Hydrogen Plasma Arc Melting

The high-temperature melting and the removal of gaseous and metallic impurities from Inconel 718 by hydrogen plasma arc melting (HPAM) were investigated. Solid-type Inconel 718 scraps were used as raw material. The concentrations of oxygen, nitrogen, and metallic impurities in the scraps were simultaneously decreased by HPAM. The refined ingot satisfied the recommended criteria for commercial Inconel 718. Following the melting of Inconel 718 by HPAM, the microstructure of the as-cast depended on different parts of the ingots, due to the different cooling rate of each part. Graphic

Automated summary

The study investigated the high-temperature melting and impurity removal process of Inconel 718 using hydrogen plasma arc melting (HPAM). The HPAM successfully decreased the concentrations of oxygen, nitrogen, and metallic impurities in the Inconel 718 scraps, producing refined ingots that met commercial standards. Additionally, the microstructure of the as-cast Inconel 718 varied depending on different parts of the ingots due to varying cooling rates.