Abstract

2219 Al alloy is an important material for manufacturing launch vehicles, and its grain structure has a substantial effect on the performance of storage tank transition rings. In this work, warm compression tests (100–350 °C) of 2219 Al alloy were carried out, a grain refinement model of warm deformation was established, and the evolution and thermal stability of the static recrystallized grain size D were analyzed. The results showed that static recrystallization is the main mechanism of grain refinement, and that the nucleation rate and grain refining effects were significantly improved by decreasing the deformation temperatures (T). The established model was found to be accurate, and the predicted and experimental values exhibited high degrees of coincidence. When T and the amount of deformation (Δd) were respectively 150 °C and 70%, the value of D was reduced from 60 μm to 21 μm. Additionally, when the solution treatment time was increased from 0 to 4 h, there was a slight change in the values of D (high thermal stability) when T was lower than 250 °C and Δd was greater than 20%, but they significantly increased when Δd was less than 10%.

Graphic Abstract

In this paper, the effects of different deformation temperatures T and deformation amount Δd on average grain size D of 2219 Al alloy forgings were investigated, and the evolution rule and thermal stability of D were analyzed. The research results showed that static recrystallization was the main mechanism for grain refinement of 2219 forgings, and the nucleation rate and grain refining effects were improved by increasing Δd and decreasing T. Warm compression was conducive to accumulating higher-density dislocations, storing more deformation energy, generating more high energy distortion points. Hence, increasing the recrystallization nucleation rate and decreasing grains growth velocity. Furthermore, the thermal stability of grain sizes increased with the decreasing recrystallization grain size and uniformity. Because there is a low energy difference between fine and uniform grains (the interface energy was very low), which led to slow grain boundary migration speed and restraining grain growth even at high temperatures.

中文翻译：

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热变形过程中2219铝合金的晶粒细化和热稳定性

摘要

2219铝合金是制造运载火箭的重要材料，其晶粒结构对储罐过渡环的性能有很大影响。在这项工作中，对2219铝合金进行了热压缩试验（100–350°C），建立了热变形的晶粒细化模型，并分析了静态再结晶晶粒度D的演变和热稳定性。结果表明，静态再结晶是晶粒细化的主要机理，并且通过降低变形温度（T）可以显着提高成核速率和晶粒细化效果。发现所建立的模型是准确的，并且预测值和实验值显示出高度一致。当T和变形的（Δ量d）分别为150℃和70％，值d是从60微米减小到21微米。另外，当溶体化处理时间从0增加到4小时，有在的值的轻微变化d（热稳定性高）时Ť比250℃，Δ下d是大于20％，但他们显著当Δ增加d是小于10％。

图形摘要

本文研究了不同变形温度T和变形量Δd对2219铝合金锻件平均晶粒尺寸D的影响，分析了D的演变规律和热稳定性。研究结果表明，静态再结晶是2219锻件晶粒细化的主要机理，通过增加Δd和减小T可以提高成核速率和晶粒细化效果。热压缩有利于积累更高密度的位错，储存更多的形变能，产生更多的高能量畸变点。因此，增加了再结晶成核速率并降低了晶粒生长速度。此外，随着再结晶晶粒尺寸和均匀性的降低，晶粒尺寸的热稳定性增加。