Tensile properties of LBW welds in Ti-6Al-4V alloy at evaluated temperatures below 450 degrees C

Abstract

The influence of temperatures below 450 °C on the tensile properties of laser beam (LB) welds in dual phase Ti–6Al–4V titanium alloy was investigated. The ultimate tensile strength of the weldment is slightly superior than that of the as-received parent materials. Conversely, the yield stress of the weldment is inferior to that of the parent metal, especially in the 150–450 °C range. The elongation of the weldment was about 5% lower than that of the parent metal for the entire temperature range. The prominent dislocation gliding on the pyramidal planes giving (101̄1) <112̄3> and (112̄2) <112̄3> type slip with low critical resolved shear stress leads to both the weldment and parent metal exhibiting the lowest ductility at a temperature range from 200 to 350 °C. The maximum hardness in the fusion zone (FZ) corresponds to the needle-like martensite α′ formed after the postsolidification phase transformation. As the temperature increases, the dimple dimension becomes larger and deeper.