Fabrication of High-Purity V-4CR-4TI Low Activation Alloy Products

Abstract

High-purity V-4Cr-4Ti low activation alloy products, such as plates and wires, were fabricated from the NIFS-HEAT-1 ingot with improvements of the conventional manufacturing processes. During fabrication, significant and small increase in hydrogen and oxygen level were observed, respectively. However, these contaminants were released by a heat treatment at 673 K or higher in a vacuum. For the purpose of obtaining an appropriate thermomechanical treatment condition, recrystallization behavior of plate products, which were 6.6, 4.0, 1.9 mm thick, was investigated after cold rolling. It was revealed that annealing at 1273 K for one to two hours provides recrystallized grains of 20-30 μm. Only in the case of 1.9 mm-thick plates which experienced large degree of cross rolling, a layer of finer grain was observed in the vicinity of the surface. The NIFS-HEAT-1 products are going through Round-robin tests by Japanese universities.