TNW700 is a newly developed near-α high temperature titanium alloy and has great application potential in the aerospace industry owing to excellent creep strength and short-term service temperature up to 700 °C. The superplastic tensile deformation behavior and constitutive model of TNW700 alloy in the temperature range of 900–975 °C and strain rate range of 0.0005–0.01s⁻¹ were investigated. Results indicated that TNW700 alloy exhibits significant work hardening behavior, which may be related to dynamic growth of β grains, dislocation evolution, and silicide precipitates. In addition, work hardening coefficient (n) as well as the critical strain between flow hardening and softening increases with decreasing strain rate, and first increases and then decreases with increasing deformation temperature. TNW700 alloy exhibits excellent superplasticity at 900 °C–950 °C corresponding to strain rate sensitivity exponent (m) greater than 0.3, and expresses poor superplasticity at 975 °C with lower m value. The m value decreases monotonously with strain owing to decrease of grain boundary sliding contribution caused by dynamic grain growth of β grains. The deformation activation energy increases with decreasing strain rate due to the change of deformation mechanism. A phenomenological constitutive model considering strain hardening, strain rate hardening and temperature softening was proposed and material constants were calibrated by true stress-strain data. The constitutive model was implemented into Abaqus code by UHARD subroutine to simulate the superplastic forming of cone parts, and thickness distribution and bulging heights under different forming time were used to verify the validity of constitutive model.

TNW700是一种新近开发的近α高温钛合金，由于其出色的蠕变强度和高达700°C的短期使用温度，在航空航天工业中具有巨大的应用潜力。研究了TNW700合金在900–975°C的温度范围和0.0005–0.01s ^-1的应变率范围内的超塑性拉伸变形行为和本构模型。结果表明，TNW700合金表现出显着的加工硬化行为，这可能与β晶粒的动态生长，位错演化和硅化物沉淀有关。另外，加工硬化系数（n）以及流动硬化和软化之间的临界应变随着应变率的降低而增加，然后随着变形温度的升高先增加然后降低。TNW700合金在900°C–950°C下表现出优异的超塑性，对应于大于0.3的应变速率敏感性指数（m），并且在975°C下具有较低的m值，表现出较差的超塑性。该米由于β晶粒的动态晶粒长大引起的晶界滑动贡献的减小，该值随应变而单调减小。由于变形机理的改变，变形激活能随应变率的降低而增加。提出了考虑应变硬化，应变速率硬化和温度软化的现象本构模型，并通过真实的应力应变数据对材料常数进行了校准。UHARD子程序将本构模型应用到Abaqus代码中，以模拟圆锥零件的超塑性成形，并使用不同成形时间下的厚度分布和凸出高度来验证本构模型的有效性。