NIFS program for large ingot production of a V–Cr–Ti alloy

The National Institute for Fusion Science (NIFS), in collaboration with Japanese industry, has initiated a research program for vanadium alloys, which will be highlighted by the production of a large V–4Cr–4Ti ingot. In this program, the technology and underlying science associated with vanadium alloy fabrication will be enhanced. Effort has been focused on the control of interstitial impurities such as C, O and N. Purification of the present commercial metal vanadium was carried out by improvement of the processes. Medium size (30 kg), high purity V–4Cr–4Ti ingots have been produced, designated as NIFS-HEAT-1, and a large size (200 kg) ingot is planned. In this study, the technology for fabricating large V–Cr–Ti ingots with ∼50 ppm C, ∼180 ppm O and ∼100 ppm N has been demonstrated.