Hot deformation behavior and microstructure evolution of hot-extruded 6A02 aluminum alloy
Hot deformation behavior and microstructure evolution of hot-extruded 6A02 aluminum alloy
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热挤压6A02铝合金的热变形行为及显微组织演变
DOI：
10.1016/j.matchar.2022.111908
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发表时间：
2022-04
影响因子：
4.7
通讯作者：
Minjie Huang
中科院分区：
文献类型：
--
作者：
Ying Zhang;Jufu Jiang;Ying Wang;Yingze Liu;Minjie Huang
研究了温度、应变速率、应变量和初始取向对热挤压6A 02铝合金热压缩行为和组织演变的影响。在两个方向上切割初始样品：平行于原始挤出方向（D1）和垂直于挤出方向（D2）。在400 °C-560 °C温度范围内，在0.001 s−1-1 s−1的恒定应变速率下，研究了D1样品的Arkenius和扩散本构模型。考虑晶格扩散的Arrhenius本构模型的预测精度优于扩散本构模型。峰值应力的平均激活能为325.114 kJ/mol。在所有应变范围内，蠕变指数n均大于5.较高的温度和较低的应变速率导致较低的几何必需位错密度、较低的应变储能和较高的动态再结晶程度。储存的应变能范围为0.534 - 0.993 J/mol。极限应力与位错密度呈线性关系。随着应变速率的增加，连续动态再结晶（CDRX）逐渐先于不连续动态再结晶（DDRX）。D1样品阶梯应变率热变形实验表明，两个阶段之间的较大间隙对提高动态再结晶程度有更有效的作用。变形机制与晶粒类型有关。D2试样的动态再结晶晶粒比例和织构类型均小于D1试样。此外，在所有恒定应变速率下，CDRX机制均上级DDRX机制。
The present work explored the impacts of temperature, strain rate, strain and initial orientation on hot-compression behavior and microstructural evolvement of hot-extruded 6A02 aluminum alloy. Initial samples were cut in two directions: parallel to the original extruding direction (D1) and perpendicular to the extruding direction (D2). Arrhenius and diffusion constitutive models of D1 samples were studied at 400 °C–560 °C under constant strain rate of 0.001 s−1–1 s−1. The predication accuracy of Arrhenius constitutive model was better than diffusion constitutive model considering lattice diffusion. The average activation energy of peak stress was 325.114 kJ/mol. Lattice diffusion was dominant diffusion mechanism and creep exponentsnwere larger than 5 in all strain ranges. Higher temperature and lower strain rate resulted in lower geometrically necessary dislocation (GND) density, lower stored strain energyEand higher dynamic recrystallization (DRX) degree. Stored strain energy ranged from 0.534 to 0.993 J/mol. The ultimate stress had linear relationship with dislocation density. The continuous dynamic recrystallization (CDRX) was gradually prior to discontinuous dynamic recrystallization (DDRX) with increase of strain rate. Hot deformation experiment of D1 samples with stepped strain rates showed that the large gaps between the two stages had more effective effect on improving DRX degree. Deformation mechanisms were in connection with grain types. For D2 sample, the fraction of DRX grains and texture types were less than D1 sample. Besides, CDRX mechanism was superior to DDRX mechanism at all constant strain rates.