Microstructure and mechanical properties of hybrid fabricated Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy by laser additive manufacturing

The hybrid fabricating technique by laser additive manufacturing provides an attractive potential for manufacturing titanium alloy components. Microstructure, micro-hardness and room tensile mechanical properties of hybrid fabricated TC11 titanium alloy sample were examined. Results show that the hybrid manufactured sample consists of three typical zones: the laser additive manufactured zone (LAMZ), the wrought substrate zone (WSZ), and the bonding zone without any metallurgical defects. Superfine basket-wave microstructure forms in LAMZ and heat affected zone (HAZ) due to the rapid cooling rate. No obvious grain growth or recrystallization occurs in the HAZ. A special bimodal microstructure consisting of coarse fork-like primary α and fine β transformed microstructure is found in the transition zone due to the heat effect in α+β region. The hybrid fabricated TC11 sample has good mechanical properties with tensile strength of 1033±13 MPa and elongation of 6.8±0.2%. The fracture of hybrid sample occurs in the substrate in tensile testing, meaning that the bonding zone has better mechanical properties than the substrate.