Dynamic recrystallisation (DRX) usually occurs during hot forming of metallic materials, significantly impacting the mechanical properties of the final parts. Although DRX has been studied for decades, the types of DRX that occurs in high stacking fault energy (SFE) materials like aluminium alloys are still controversial, and their dependence on both temperature and strain rate is surprisingly missing. To fill these gaps, in the present study, uniaxial compression tests on an aluminium alloy AA6061 were carried out at different temperatures from 250 to 475 °C and strain rates from 0.01 to 1 s. The grain orientation and misorientation before and after the hot deformation were quantitively characterised using high-resolution Electron Backscatter Diffraction (EBSD) with a misorientation resolution of 0.05°, enabling high-angle grain boundaries (HAGBs), low-angle grain boundaries (LAGBs) and geometrically necessary dislocations (GNDs) to be accurately quantified and correlated against temperature and strain rate. Results reveal that both continuous dynamic recrystallisation (CDRX) and geometric dynamic recrystallisation (GDRX) occurred concurrently, resulting in the formation of discontinuous HAGBs and fine equiaxed grains, respectively. The misorientation angle distributions of the discontinuous HAGBs exhibit an opposite trend compared to those of the fine grains’ HAGBs. Both temperature and strain rate significantly affect the density of HAGBs formed by DRX, but have little effect on their misorientation angle distributions. This study sheds light on the fundamental understanding of DRX and provides comprehensive experimental data for future modelling of DRX processes in high SFE materials.

中文翻译：

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动态再结晶：铝合金中晶界特征及其对温度和应变速率依赖性的定量研究


动态再结晶（DRX）通常发生在金属材料的热成型过程中，显着影响最终零件的机械性能。尽管 DRX 已经被研究了几十年，但在铝合金等高堆垛层错能 (SFE) 材料中发生的 DRX 类型仍然存在争议，而且令人惊讶的是，它们对温度和应变率的依赖性却被忽略了。为了填补这些空白，在本研究中，在 250 至 475 °C 的不同温度和 0.01 至 1 s 的应变速率下对铝合金 AA6061 进行了单轴压缩试验。使用高分辨率电子背散射衍射 (EBSD) 定量表征热变形前后的晶粒取向和取向差，取向差分辨率为 0.05°，从而实现高角度晶界 (HAGB)、低角度晶界 (LAGB)以及几何必要位错 (GND) 的精确量化并与温度和应变率相关联。结果表明，连续动态再结晶 (CDRX) 和几何动态再结晶 (GDRX) 同时发生，分别导致不连续 HAGB 和细等轴晶粒的形成。与细晶粒 HAGB 相比，不连续 HAGB 的取向差角分布呈现出相反的趋势。温度和应变速率均显着影响 DRX 形成的 HAGB 的密度，但对其取向差角分布影响不大。这项研究揭示了对 DRX 的基本理解，并为未来高 SFE 材料中 DRX 过程的建模提供了全面的实验数据。