Microstructure and mechanical properties of laser welded Ti–10V–2Fe–3Al (Ti1023) titanium alloy

Abstract

The microstructure, microhardness, tensile properties, and fracture characteristics of the laser welded Ti–10V–2Fe–3Al (Ti1023) titanium alloy in the as-welded condition were examined. The mechanical properties were related to the microstructure development across the weld. In the base material (BM), the primary α phase with spherical and lath morphologies was dispersed in the β matrix. The volume fraction of the α phase in the heat affected zone (HAZ) decreased to some extent compared to the BM as a result of its partial dissolution and/or transformation to the β phase. In the fusion zone (FZ), primary α phase was completely transformed to the β phase. The BM exhibited a higher hardness than HAZ and FZ due to a higher volume fraction of the primary α phase, which is harder than β phase. The yield strength (YS) and ultimate tensile strength (UTS) of the weldments were somewhat lower than those of the BM due to the presence of a softer phase in the FZ and a lower volume fraction of the α phase in the HAZ. Also, the presence of porosity, undercut, concavity, and coarse columnar β grains in the FZ contributed to lower YS, UTS, and total elongation in the weldments in comparison to the unwelded material. Examination of the fracture surface in the weldment tensile samples indicated a mixed brittle and ductile fracture mode.

Keywords

• Titanium alloy
• Laser welding
• Microstructure
• Mechanical properties