Compression Characteristic and Tensile Property in an (Alpha+Beta)-Type Titanium Alloy at High Temperature

摘要

The behavior of hot deformation, mechanical properties and microstructures in Ti-6Al-4V alloy with Widmanstatten structure and with equiaxed-grain structure were studied. In Ti-6Al-4V alloy, with increasing compression temperature and decreasing the strain rate the peak flow stress, σ{sub}p, falls, the strain at peak flow stress, ε{sub}p, reduces and the attenuation ratio of flow stress, Δσ{sub}0.5/σ{sub}p, enhances; The flow softening is mainly related to the dynamic recovery at 600°C and to the dynamic recrystallization at temperatures 800°C and 900°C. In specimens with equiaxed-grain structure, the flow stress of hot compressive deformation is lower than that in those with Widmanstatten structure. The tensile properties of the alloy were measured at room temperature and 600°C, and at strain rates l.7×10{sup}(-3)s{sup}(-1) and 1.7×10{sup}(-1)s{sup}(-1), respectively. In specimens with equiaxed-grain structure, the strength is lower and the plasticity is higher at 600°C compared with those with Widmanstatten structure. The fracture of the alloy mainly occurs by microvoid coalescence. With increase in temperature and decrease in strain rate, the strength declines and the elongation rises and the evidence of the accompanying deformation becomes more on the fracture surfaces and the plasticity of the alloy is improved.