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 a and fine p transformed microstructure is found in the transition zone due to the heat effect in alpha+beta 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. (C) 2014 Elsevier B.V. All rights reserved.