Thixoforming-forging compound forming technology for 6A02 Al bracket-shape component
Thixoforming-forging compound forming technology for 6A02 Al bracket-shape component
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6A02铝支架形件触变-锻造复合成形技术
DOI：
10.1016/j.ijmecsci.2022.107881
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发表时间：
2022-10
影响因子：
7.3
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
传统的触变成形技术具有铸造和锻造的优点，但塑性变形程度低，且液相的存在降低了力学性能。本工作首次采用高效触变成形-锻造复合成形技术和双峰半固态坯料制造了6A02支架形构件。由于晶内位错和细长的晶粒形状，双峰半固体原料有利于填充能力和机械强度。首先，通过控制温度场分布建立了复合成形的Deform-3D模拟。然后研究了坯料形状、坯料温度、均热时间、模具温度和保压时间对显微组织和力学性能的影响。虽然在一体成形过程中，由于较大的塑性变形，肩部的机械强度和延展性有所提高，但由于液体偏析，它们仍然低于侧壁和底部的机械强度和延展性。此外，复合成形的6A02构件的最大屈服强度σy、抗拉强度σmax和伸长率δ甚至比6A02热挤压棒材的σy、σmax和δ分别高出16.8%、25.8%和77.6%。最后，对复合成形技术的变形行为和强化机理进行了深入探讨。特别是，除液体部分外，变形行为与晶粒尺寸和形态有关。对于更圆和更小的晶粒，晶界滑动占主导地位。但对于大变形晶粒来说，滑移变形占主导地位。随后，提出了一种新的动态再结晶（DRX）机制，只有连续动态再结晶（CDRX）才能使湿晶界呈锯齿状。对强化机制的定量分析表明，固溶强化和位错强化占主导地位。该研究为6A02合金在复合成形领域的高效应用和成形控制提供了理论指导和实验支撑。
Conventional thixoforming technology had advantages of casting and forging, but low plastic deformation degree and existence of liquid phase lowered the mechanical property. In this work, 6A02 bracket-shape component was firstly manufactured by the efficient thixoforming-forging compound forming technology and bimodal semisolid billet. Bimodal semisolid feedstock was beneficial for both filling ability and mechanical strength due to intragranular dislocation and elongated grain shape. Firstly, a Deform-3D simulation of compound forming was established by controlling temperature field distribution. Then the effects of billet shapes, billet temperatures, soaking times, mold temperatures and dwell times on microstructures and mechanical properties were investigated. Though the mechanical strength and ductility at the shoulder were elevated by larger plastic deformation in the integrated forming process, they were still lower than those at side wall and bottom part in virtue of liquid segregation. Besides, the largest yield strength σy, tensile strength σmaxand elongation δ of compound-formed 6A02 components were even 16.8%, 25.8%, and 77.6% higher than σy, σmaxand δ of 6A02 hot-extruded bar, respectively. Finally, the deformation behavior and strengthening mechanism of compound forming technology were discussed deeply. Particularly, except liquid fraction, deformation behavior was relevant with grain size and morphology. For rounder and smaller grains, grain boundary sliding was dominant. But slip deformation was predominant for large-deformed grains. Subsequently, a new dynamic recrystallization (DRX) mechanism was proposed and only continuous dynamic recrystallization (CDRX) could make the wet grain boundary serrated. A quantitative insight into strengthening mechanism indicated that solid solution strengthening and dislocation strengthening were dominant. This study provided a theoretical guidance and experimental support for the efficient application and forming control of 6A02 alloy in compound forming area.
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影响因子：
6.3
作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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影响因子：
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