中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 26 No. 8 August 2016 |
(State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China)
Abstract:The microstructure, microhardness and tensile properties of laser additive manufactured (LAM) Ti-5Al-2Sn-2Zr-4Mo- 4Cr alloy were investigated. The result shows that the microstructure evolution is strongly affected by the thermal history of LAM process. Primary α (αp) with different morphologies, secondary α (αs) and martensite α'''' can be observed at different positions of the LAMed specimen. Annealing treatment can promote the precipitation of rib-like α phase or acicular α phase. As a result, it can increase or decrease the microhardness. The as-deposited L-direction and T-direction specimens contain the same phase constituent with different morphologies. The tensile properties of the as-deposited LAMed specimens are characterized of anisotropy. The L-direction specimen shows the character of low strength but high ductility when compared with the T-direction specimen. After annealing treatment, the strength of L-direction specimen increases significantly while the ductility reduces. The strength of the annealed T-direction specimen changes little, however, the ductility reduces nearly by 50%.
Key words: Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy; laser additive manufacture; microstructure; thermal history; mechanical properties