Abstract Development of a hybrid constitutive model for modelling of the flow behavior, microstructure evolution, damage initiation and fracture formation is crucial in study of hot deformation of titanium alloys. In tandem with this, a microstructure and damage based constitutive model for modelling of hot working of Ti–6Al–2Zr–1Mo–1V (TA15) alloy was developed. The hot tension deformation of the alloy was first conducted to analyze the microstructure evolution, damage and flow behaviors. It was found that increasing β phase fraction and dynamic recrystallization (DRX) fraction suppress the damage initiation and propagation in the way of void nucleation, growth and coalescence, and thus foster the increase of fracture strain in an exponential form. Based on the experimental results, the microstructure evolution, including phase transformation and DRX occurrence, was modelled by using the method represented by physically-based internal state variables. The damage and fracture behaviors were modelled by considering the effects of microstructure and stress state via introducing β phase fraction, DRX fraction and stress triaxiality into the classical Gurson-Tvergaard-Needleman damage model. The constitutive law considering both the microstructure and damage evolution was then given and further the microstructure and damage based constitutive model was established. The parameters in the model were calibrated by comparing the predicted and experimental results. Finally, the developed model was successfully applied in finite element simulation of hot spinning of TA15 alloy tube for unified prediction of macroscopic deformation, microstructure, damage and fracture. The research thus provides a basis for tailoring and control of microstructure and damage in hot working of titanium alloys.

中文翻译：

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基于组织和损伤的钛合金热变形本构建模

摘要 开发用于模拟流动行为、微观结构演变、损伤起始和断裂形成的混合本构模型对于研究钛合金的热变形至关重要。与此同时，开发了一种基于微观结构和损伤的本构模型，用于模拟 Ti-6Al-2Zr-1Mo-1V (TA15) 合金的热加工。首先进行合金的热拉伸变形以分析显微组织演变、损伤和流动行为。结果表明，增加β相分数和动态再结晶（DRX）分数可以抑制空洞形核、生长和聚结的损伤萌生和扩展，从而促进断裂应变呈指数形式增加。根据实验结果，微观结构演变，包括相变和 DRX 发生，是通过使用由基于物理的内部状态变量表示的方法建模的。通过在经典的 Gurson-Tvergaard-Needleman 损伤模型中引入 β 相分数、DRX 分数和应力三轴度，考虑微观结构和应力状态的影响，对损伤和断裂行为进行建模。然后给出了考虑微观结构和损伤演化的本构规律，并进一步建立了基于微观结构和损伤的本构模型。通过比较预测结果和实验结果对模型中的参数进行校准。最后，将开发的模型成功应用于TA15合金管热旋压有限元模拟，统一预测宏观变形、显微组织、损坏和断裂。因此，该研究为钛合金热加工过程中微观结构和损伤的调整和控制提供了基础。