Deformation behavior and microstructural evolution during hot compression of an a+b Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy

Gao-feng Liu1), Shang-zhou Zhang1), Li-qing Chen2), and Jian-xun Qiu1) 1) School of Environmental and Materials Engineering, Yantai University, Yantai 264005, China 2) State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110004, China

摘 要：The effect of processing parameters on the flow response and microstructural evolution of the a+b titanium alloy Ti-6.5Al-3.5Mo-1.5Zr-0.3Si has been studied by conducting isothermal hot compressive tests at a strain rate of 0.01-10 s-1 at 860-1100°C. The true stress-true strain curves of the sample hot-compressed in the a+b phase region exhibit a peak stress followed by continuous flow softening, whereas in the b region, the flow stress attains a steady-state regime. At a strain rate of 10 s-1, the alloy exhibits plastic flow insta-bilities. According to the kinetic rate equation, the apparent activation energies are estimated to be about 674-705 kJ/mol in the a+b region and 308-335 kJ/mol in the b region, respectively. When deformed in the a+b region, the globularization process of the a colony structure occurs, and a dynamic recrystallized microstructures are observed to show bimodal. Dynamic recrystallization can take place in the b region irrespective of starting deformed structures.

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