Ti-6Al-4V 合金の機能性および強度に及ぼす複合処理の効果

Abstract

This study was conducted to comprehensively investigate the effect of combination treatment on the wear resistance, corrosion resistance, mechanical properties and fatigue strength of Ti-6Al-4V alloy. The combination treatment was composed of plasma nitriding, short-time heat treatment and fine-particle bombarding (hereafter, FPB). Plasma nitriding was performed at 1123 K. The obtained results were compared with those of the previous study concerning the combination treatment in which plasma nitriding was performed at 1023 K. A thick hardened layer (thickness: 200 μm) was formed by plasma nitriding. The substrate was strengthened by short-time heat treatment. The surface brittle compound layer was eliminated by FPB, and high compressive residual stress was introduced at the same time. The combination treatment improved wear resistance without the deterioration of corrosion resistance. Moreover, the combination treatment improved tensile strength and fatigue strength although it markedly reduced ductility. The comparison with the results obtained in the previous study showed that the combination treatment in which plasma nitriding was performed at 1023 K was more effective to improve the functionalities and strength of Ti-6Al-4V alloy.