Microstructure Distribution and Tensile Anisotropy of Dissimilar Friction Stir Welded AM60 and AZ31 Magnesium Alloys
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Microstructure Distribution and Tensile Anisotropy of Dissimilar Friction Stir Welded AM60 and AZ31 Magnesium Alloys Jun‑Lei Zhang1,2 · Han Liu1,2 · Yu‑Lu Xie1,2 · Guang‑Sheng Huang1,2 · Xiang Chen1,2 · Bin Jiang1,2 · Ai‑Tao Tang1,2 · Fu‑Sheng Pan1,2 Received: 14 April 2020 / Revised: 5 May 2020 / Accepted: 11 May 2020 © The Chinese Society for Metals (CSM) and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The microstructure distribution, tensile anisotropy and fracture behaviors in the dissimilar friction stir welded joint of AM60/ AZ31 alloys were investigated. Experimental results showed that a significant grain refinement and an orientation fluctuation occurred in the weld. The grain size of AZ31 side in joint was obviously smaller than that of AM60 side. There was a higher percentage of low angle grain boundaries (LAGBs) and a lower degree of recrystallization in AZ31 side compared with those in AM60 side, especially for the thermo-mechanically affected zone in AZ31 side. The discrepancies of grain size distribution, recrystallization behavior and LAGBs in joint depended on the different initial state of two metals and the inhomogeneous temperature distribution in joint. In addition, the (0001) basal plane in weld was roughly parallel to the surface of the pin, showing the symmetrically distributed texture characteristics. The joint showed an obvious tensile anisotropy due to the special texture distribution. The comprehensive tensile properties of joint along the three directions decreased in the order: welding direction, 45° direction and transverse direction. The maximum ultimate tensile strength, yield strength and elongation of the joint were 242 MPa, 116 MPa and 21.2%, respectively. The fluctuations of grain size and texture in joint affected the fracture behavior of samples in the three directions. Keywords Friction stir welding · Dissimilar joint · Texture · Anisotropy · Tensile properties
1 Introduction Mg alloys are regarded as the most potential structural material in the future of automotive and aerospace fields due to their advantages such as high specific strength and low density [1–3]. However, few slip systems can be activated at room temperature because of the hexagonal closepacked structure of the Mg alloy [1, 4, 5], which leads to its poor formability. Fortunately, welding, as an indispensable Available online at http://link.springer.com/journal/40195. * Guang‑Sheng Huang [email protected] * Bin Jiang [email protected] 1
State Key Laboratory of Mechanical Transmission, College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
National Engineering Research Center for Mg Alloys, Chongqing University, Chongqing 400044, China
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manufacturing method in industrial production, can largely compensate for the poor formability of Mg alloys. Friction stir welding (FSW) is known as the second revolution in welding history after laser welding [6]. It can realize the welding of metals without melting and therefore effectively a
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