Plastic Flow Instability Behavior of TA15 Titanium Alloy with β Transformed Microstructure

An isothermal constant strain rate compression test was performed on TA15 titanium alloy with two types of beta transformed microstructures of basket-weave and Widmannstatten in the temperature range of 750 similar to 950 degrees C and the strain rate range of 0.001 similar to 10 s(-1). The results show that there is a wide range of plastic flow instability in the two beta transformed microstructures in low temperature and high strain rate regions (750 similar to 880 degrees C, 0.0032 similar to 10 s(-1)). The instability range of Widmannstatten microstructure is larger than that of the basket -weave microstructure. The instability defects of Widmannstatten microstructure mainly include 45 macro shear crack, microcrack and flow localization band, while the defects of basket-weave microstructure are chiefly 45 macro shear crack and flow localization band. The plastic flow instability is more likely to occur in Widmannstatten microstructure than in the basket-weave one, which is primarily due to the poor deformation coordination caused by the coarse lamellar a in Widmannstatten microstructure.