关键词: 选区激光熔化, 钛合金, 热处理, α′相, 拉伸性能

Abstract: TC4 titanium alloy specimens were prepared by using selective laser melting (SLM) technology, and the effect of heat treatment conditions on the α′ phase transformation in microstructure and mechanical properties was investigated by using optical microscope and universal testing machine. The results show that the macroscopic structure of the deposited TC4 alloy is epitaxial β columnar crystal, and the microstructure consists of a large number of α′ phases, α phases, and dispersed β phases. As the annealing temperature increases, the solubility of β phase gradually becomes smaller, the tendency of β transformation of α′ phase gradually becomes larger, and the coarsening of α phase is more obvious. When the solution treatment temperature is 900 ℃, α′ phase is almost completely decomposed, and there are a large number of supersaturated metastable β phases. With the increase of aging temperature, the amount of precipitated secondary α phase is more, and the shape gradually changes from needle-like to lamellar. The mechanical properties of the alloy generally exhibit a trend of decreasing strength and increasing elongation. After comparison, the comprehensive mechanical properties of the TC4 alloy solution treated at 900 ℃ for 1 h(AC) and aged at 500 ℃ for 2 h(AC) are the best.

Key words: selective laser melting, titanium alloy, heat treatment, α′ phase, tensile properties