基于温升修正的挤压态Ti-6554合金本构模型和微观组织演化

Constitutive Model and Microstructure Evolution of As- extruded Ti-6554 Alloy Based on Temperature Rise Correction

摘要:

在700–950 ℃、0.001–1 s^-1的等温压缩条件下，研究了挤压态Ti-6554合金的热变形行为。计算了不同变形条件下的温升，对曲线进行了温升修正，建立了基于温升修正的挤压态Ti-6554合金的应变补偿本构模型。分析了不同条件下的微观组织演化规律，揭示了动态再结晶（DRX）机制。结果表明，流动应力随着应变速率的增加和变形温度的降低逐渐下降。变形温升随着应变速率的增加和变形温度的降低逐渐增加。在700 ℃/1 s^-1时，温升达到100 ℃。修正后的曲线值高于测量值，应变补偿本构模型预测精度较高。在两相区变形时析出了α相，进而促进了β相的DRX过程。低应变速率下，随着变形温度升高，动态再结晶体积分数增加。DRX机制包含连续DRX和非连续DRX。

Abstract:

The hot deformation behavior of as-extruded Ti-6554 alloy was investigated through isothermal compression at 700– 950 °C and 0.001–1 s^-1. The temperature rise under different deformation conditions was calculated, and the curve was corrected. The strain compensation constitutive model of as-extruded Ti-6554 alloy based on temperature rise correction was established. The microstructure evolution under different conditions was analyzed, and the dynamic recrystallization (DRX) mechanism was revealed. The results show that the flow stress decreases with the increase in strain rate and the decrease in deformation temperature. The deformation temperature rise gradually increases with the increase in strain rate and the decrease in deformation temperature. At 700 °C/1 s^-1, the temperature rise reaches 100 °C. The corrected curve value is higher than the measured value, and the strain compensation constitutive model has high prediction accuracy. The precipitation of the α phase occurs during deformation in the two-phase region, which promotes DRX process of the β phase. At low strain rate, the volume fraction of dynamic recrystallization increases with the increase in deformation temperature. DRX mechanism includes continuous DRX and discontinuous DRX.