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<p>During the high-speed cutting (HSC) of Ti-6Al-4&#xa0;V, the change of microstructures in shear band caused by severe plastic deformation (SPD) and thermomechanical coupling can greatly affect the mechanical response and machining performance of material. To accurately explore the corresponding microstructural evolution, an optimized finite element (FEM) model is established based on a modified constitutive and metallurgical-thermomechanical coupling (MCMTC) model. The proposed MCMTC model integrates a modified Johnson-Cook (J-C) constitutive model with the effects of phase transformation. Among which, the dynamic recrystallization (DRX) as a softening mechanism and the coupling terms of temperature and work hardening (WH) are introduced into the modified J-C model. In order to reflect the volumetric strain induced by phase transformation within shear band, the strain increment coupling is considered. The optimized FEM model is validated at micro and macro scales by comparing experimental data on chip morphology, cutting force, grain size, and micro-hardness. The results show that the increase of cutting speed can enhance strain, strain rate, temperature, and DRX behavior, which in turn promotes the grain refinement, micro-hardness and phase transformation in shear band. The DRX predominantly occurs in the shear band region characterized by high strain and high temperature, and the phase transformation behavior exhibits obvious thermo-driven characteristics. Moreover, the evolution of α and β phases and the volumetric strain are strongly correlated with the thermal field. These findings demonstrate that the optimized FEM model is accurate and effective in capturing the microstructural evolution in shear band during the HSC of Ti-6Al-4&#xa0;V.</p>

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Microstructural Evolution of Ti-6Al-4 V Alloy During High-Speed Cutting Based on Modified Constitutive and Metallurgical-Thermomechanical Coupling Model

  • 期刊论文

  • 发表日期：

    2025年10月17日

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  • Qianwei Jiang,
  • Xianfu Liu,
  • Fazhan Li,
  • Li Li,
  • Jinguo Han,
  • Yingyue Yin,
  • Yang Hua,
  • Pengcheng Yan

摘要

During the high-speed cutting (HSC) of Ti-6Al-4 V, the change of microstructures in shear band caused by severe plastic deformation (SPD) and thermomechanical coupling can greatly affect the mechanical response and machining performance of material. To accurately explore the corresponding microstructural evolution, an optimized finite element (FEM) model is established based on a modified constitutive and metallurgical-thermomechanical coupling (MCMTC) model. The proposed MCMTC model integrates a modified Johnson-Cook (J-C) constitutive model with the effects of phase transformation. Among which, the dynamic recrystallization (DRX) as a softening mechanism and the coupling terms of temperature and work hardening (WH) are introduced into the modified J-C model. In order to reflect the volumetric strain induced by phase transformation within shear band, the strain increment coupling is considered. The optimized FEM model is validated at micro and macro scales by comparing experimental data on chip morphology, cutting force, grain size, and micro-hardness. The results show that the increase of cutting speed can enhance strain, strain rate, temperature, and DRX behavior, which in turn promotes the grain refinement, micro-hardness and phase transformation in shear band. The DRX predominantly occurs in the shear band region characterized by high strain and high temperature, and the phase transformation behavior exhibits obvious thermo-driven characteristics. Moreover, the evolution of α and β phases and the volumetric strain are strongly correlated with the thermal field. These findings demonstrate that the optimized FEM model is accurate and effective in capturing the microstructural evolution in shear band during the HSC of Ti-6Al-4 V.