Parameter optimization of extrusion-Bc ECA technology and its effect on microstructure and properties of 7075 aluminum a
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Parameter optimization of extrusion‑Bc ECA technology and its effect on microstructure and properties of 7075 aluminum alloy Xiaojing Xu1 · Hao Chen1 · Ze Jiang1 · Vitus Tabie1 · Qingjun Liu1 · Xu Zhang1 · Qiang Mao1 · Xiaoyu Zhang1 Received: 7 January 2020 / Accepted: 20 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Equal-Channel Angular Pressing (ECAP) was carried out on 7075 aluminum alloy with a process route of Bc mode, thus, achieving the aims of refining crystal grains and improving alloy plasticity. To save cost and optimize the ECAP process, DEFORM finite element simulation of the ECAP extrusion process was conducted to determine the ratio of die shear Angle to extrusion. The results show that the mold optimum process parameters are 135° for the shear angle (Φ) and λ = 2 the extrusion ratio. The deformation and processing stability of the alloy at the same time met the requirements. From the simulation and experimental results of the ECAP sample, the grain size of 7075 aluminum alloy after Bc-ECAP was obviously refined from 17.311 to 9.310 μm, and the grain shape more round. The equiaxed property of the grain was also improved, and the tissue distribution more uniform. Even though the strength of 7075 aluminum alloy slightly decreased, its plasticity increased significantly from 9.9 to 18.6%. Keywords 7075 aluminum alloy · ECAP · DEFORM finite element simulation · Plasticity
1 Introduction The 7000 series aluminum alloy is characterized by lightweight, high strength, and excellent machining performance. It is widely used in the aviation industry, military field, ship structure, and high-speed train [1–4]. However, the 7000 series aluminum alloy has low plasticity and corrosion resistance which need to be improved, since it is limited by applications. In scientific research, there are many related technologies that can improve its performance (such as plasma modification technology). Equal-Channel Angular Pressing (ECAP) is one effective method to improve the internal structure of the alloy and refine the crystal grains through large plastic deformation, thus, improving the plasticity, corrosion resistance, and further enhancing the strength of the alloy [5–7]. Many research results show that ECAP technology can significantly refine the alloy grain, improve the microstructure uniformity, and improve the plasticity of the alloy. Alihosseini et al. [8] found that the * Xiaojing Xu [email protected] 1
Engineering Institute of Advanced Manufacturing and Modern Equipment Technology, Jiangsu University, Zhenjiang 212013, China
average grain size of AA6061 aluminum alloy was refined from 20 μm to 212 nm after 8 ECAP passes, and the final yield stress was 330 MPa. Sabbaghianrad et al. [9] treated 7075 aluminum alloy with 8 ECAP treatments and 20 highpressure torsion (HPT) treatments, and the minimum grain size attained was about 200 nm with an increase in the hardness of the alloy. Tang et al. [10] found that after 16 ECAP treatments on Al–Zn–Mg–0.1Sc–0.1Zr alloy, the grain s
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