Ｔｉ‐６Ａｌ‐４Ｖ合金の機械的性質に及ぼす大気中（α＋β）ＳＴＡ処理および表面仕上げの影響

Abstract

When Ti-6Al-4V alloy was solution-treated and aged (STA) in air, the oxygen contaminated layer which consisted of an embrittle layer and a hardened layer was formed below the TiO2 scale. The influence of the oxygen contaminated layer was studied on the mechanical properties (static tensile properties and fatigue strength). Except the 0.2% proof stress and tensile strength, the static tensile properties and fatigue strength were degraded by the embrittle layer. On the other hand, the hardened layer hardly influenced on the mechanical properties.Furthermore, the influences of mechanical polishing and electropolish were discussed on the fatigue strength of annealed and STA materials. As a result, it was found that the mechanical polishing was effective to the improvement of the fatigue strength of annealed material.