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Kwang Tae Son, Chang Hee Cho, Myoung Gyun Kim, and Ji Woon Lee, Two-stage dynamic recrystallization and texture evolution in Al–7Mg alloy during hot torsion, Int. J. Miner. Metall. Mater., 31(2024), No. 8, pp.1900-1911. https://dx.doi.org/10.1007/s12613-024-2877-9
Kwang Tae Son, Chang Hee Cho, Myoung Gyun Kim, and Ji Woon Lee, Two-stage dynamic recrystallization and texture evolution in Al–7Mg alloy during hot torsion, Int. J. Miner. Metall. Mater., 31(2024), No. 8, pp.1900-1911. https://dx.doi.org/10.1007/s12613-024-2877-9
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Al–7Mg合金在热扭转阶段的动态再结晶与织构演变

摘要: 为探讨渐进动态再结晶(DRX)和织构行为,本文在300–500°C的温度和0.05–5 s–1的应变速率下,对Al–7Mg合金进行了热扭转试验。实验发现,Al–7Mg合金的DRX行为分为两个阶段:(1)应变≤2和(2)应变≥2。在第1阶段,DRXed颗粒分数(XDRX)略有增加,以不连续动态再结晶(DDRX)为主,随后XDRX略有变化,直到过渡到第2阶段。第2阶段以DRX的加速为标志,最终达到XDRX≈0.9。此阶段样品的电子背散射衍射(EBSD)分析表明,连续动态再结晶(CDRX)主要发生在(12(–)1)001晶粒内,而(111)110晶粒经历了几何动态再结晶(GDRX)演变,没有明显的亚晶粒结构。此外,利用改进的Avrami DRX动力学模型预测了在DRX演化过程中Al–7Mg合金的微观结构变化。尽管该动力学模型没有准确地捕捉到第1阶段的DDRX行为,但它有效地模拟了第2阶段的DRX速率。纹理指数用于评估热扭转试验期间纹理各向同性的演变,表明在第2阶段开始之前,纹理随机性显著改善(>75%),这可以归因于母体晶粒的旋转和亚结构演变,而不是XDRX的增加。

 

Two-stage dynamic recrystallization and texture evolution in Al–7Mg alloy during hot torsion

Abstract: Hot torsion tests were performed on the Al–7Mg alloy at the temperature ranging from 300 to 500°C and strain rates between 0.05 and 5 s−1 to explore the progressive dynamic recrystallization (DRX) and texture behaviors. The DRX behavior of the alloy manifested two distinct stages: Stage 1 at strain of ≤2 and Stage 2 at strains of ≥2. In Stage 1, there was a slight increase in the DRXed grain fraction (XDRX) with predominance of discontinuous DRX (DDRX), followed by a modest change in XDRX until the transition to Stage 2. Stage 2 was marked by an accelerated rate of DRX, culminating in a substantial final XDRX of ~0.9. Electron backscattered diffraction (EBSD) analysis on a sample in Stage 2 revealed that continuous DRX (CDRX) predominantly occurred within the ( 1 \bar2 1) 001 grains, whereas the (111) 110 grains underwent a geometric DRX (GDRX) evolution without a noticeable sub-grain structure. Furthermore, a modified Avrami’s DRX kinetics model was utilized to predict the microstructural refinement in the Al–7Mg alloy during the DRX evolution. Although this kinetics model did not accurately capture the DDRX behavior in Stage 1, it effectively simulated the DRX rate in Stage 2. The texture index was employed to assess the evolution of the texture isotropy during hot-torsion test, demonstrating significant improvement (>75%) in texture randomness before the commencement of Stage 2. This initial texture evolution is attributed to the rotation of parent grains and the substructure evolution, rather than to an increase in XDRX.

 

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