Effect of Yttrium Addition on Mechanical Properties for V-4Cr-4Ti Alloy Contaminated with Oxygen and Nitrogen Impurities

Abstract

Reduction of interstitial impurities such as nitrogen (N) and oxygen (O) improves the mechanical properties of V-4Cr-4Ti alloys. Yttrium (Y) addition effectively reduces O content by Y 2 O 3 slag-out on the melting ingot surface. The effects of Y addition on mechanical properties were investigated for V-4Cr-4Ti with N ranging from 0.009 to 0.29 mass% and O ranging from 0.009 to 0.36 mass%. The increase in yield stress (YS) and ultimate tensile stress (UTS) for vanadium alloys was saturated above 0.1 mass% in O content, because Ti precipitates increased with increasing O content regardless of Y addition. Y addition had little effect on YS and UTS of V-4Cr-4Ti alloys at room temperature (RT). However, Y addition improved impact properties of alloys highly doped with O. Y addition did not suppress hardening due to O doping but did increase deformation for crack initiation.