Abstract

In the current study, aluminium 6063 alloy (AA6063) was successfully gain refined by twist extrusion (TE) technique. TE is a representative severe plastic deformation process to fabricate ultrafine-grained in bulk materials by repetitive passes. In order to investigate the influence of back pressure, a direct extrusion (DE) channel was embedded after the twist zone and the behavior of AA6063 was investigated and compared with and without this channel. Analyzing microstructural evolutions by scanning electron microscope and Vickers microhardness evaluations showed that, adding the DE channel increased the hardness distribution and a more homogenous structure was obtained. Finite element analysis was utilized to study the distribution of the equivalent plastic strain (PEEQ) numerically. According to the obtained results, with applying the TE process, strain increase was observed all over the sample surface, whereas modeling the DE channel after the twist zone caused a better homogeneity in the PEEQ distribution of the transverse cross-section. The PEEQ distribution during TE process can be correlated to the extent of grain refinement and the uniformity of ultrafine grains. This method seems to be very interesting and very promising for the future industrial application.

Graphic Abstract

中文翻译：

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反压对扭挤工艺影响的计算与实验研究

摘要

在目前的研究中，铝 6063 合金 (AA6063) 通过扭曲挤压 (TE) 技术成功获得细化。TE 是一种具有代表性的严重塑性变形工艺，通过重复加工在大块材料中制造超细晶粒。为了研究背压的影响，在扭曲区之后嵌入了一个直接挤压 (DE) 通道，研究了 AA6063 的行为，并比较了有和没有这个通道的情况。通过扫描电子显微镜和维氏显微硬度评估分析显微组织演变表明，添加 DE 通道增加了硬度分布，并获得了更均匀的结构。有限元分析用于数值研究等效塑性应变（PEEQ）的分布。根据得到的结果，应用 TE 过程，在整个样品表面都观察到应变增加，而在扭曲区之后模拟 DE 通道导致横截面 PEEQ 分布的更好的均匀性。TE 过程中的 PEEQ 分布可以与晶粒细化程度和超细晶粒的均匀性相关。这种方法似乎很有趣，对未来的工业应用很有前景。

图形摘要