Effect of solution temperature on microstructures and tensile properties of high strength Ti–6Cr–5Mo–5V–4Al alloy

Abstract

The effect of solution treatment on microstructural characteristics and tensile properties of a new high strength Ti–6Cr–5Mo–5V–4Al alloy was studied. The microstructure–mechanical property relationship is also discussed. The results show that, the Ti–6Cr–5Mo–5V–4Al alloy in solution treated condition has moderate strength levels (800–1000MPa) with an excellent ductility (−22% of the elongation and 50–60% of the reduction of area). The alloy in the α/β-solution and aged (α/β-STA) condition shows a more attractive combination of strength and ductility than the alloy in the β-solution and aged condition (β-STA). The α/β-STA results in the occurrence of mixed α precipitates at nano-scale (−100nm) and at micron-scale (1μm), which contributes to the high ultimate strength levels (1400–1600MPa). However, the fine β grains below 10μm and the primary α phase contribute to good ductility (6–13.5% of the elongation and 22–52% of the reduction of area). The β-ST leads to equiaxed and coarsen β grains (40–100μm), and subsequent aging contributes to the α phase with the size of 1–5μm. The β-STA microstructure contributes to 1200–1400MPa of the ultimate strength with 7–10% of the elongation and 22–28% of the reduction of area, which shows less attractive behavior on the properties than that of the α/β-STA.