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Effect of Strain Rate on the Microstructure and Texture Evolution of the ZK60 Alloy Sheets Hongge Yan1,2 · Qin Wu1,2   · Jihua Chen1,2 · Weijun Xia1,2 · Min Song3 · Bin Su1,2 · Biao Huang1,2 Received: 3 August 2020 / Accepted: 7 September 2020 © The Korean Institute of Metals and Materials 2020

Abstract  The dynamic recrystallization (DRX), precipitation and texture evolution of the ZK60 alloy sheets rolled at 300 °C with different strain rates were studied, and the effects of texture on the plasticity were also clarified. The DRX grain sizes at five strain rates (5–25 s−1) are 1.4 μm, 1.2 μm, 1.8 μm, 2.4 μm and 2.8 μm, respectively, while the DRX volume fractions are 35.8%, 75.0%, 82.0%, 88.0% and 93.0%, respectively. The maximum intensity values of the (0002) texture are 7.91, 8.22, 7.64, 5.76 and 5.34 at five strain rates, respectively. The strongest (0002) texture is observed at the strain rate of 10 s−1, which is related to the relatively low DRX volume fraction and the precipitation density. The tensile strength (UTS) and yield strength (YS) increases firstly and then decreases, while the elongation (EL) gradually increases with increasing the strain rate, suggesting that the plasticity of the alloy sheet can be improved by decreasing the basal texture intensity and increasing the dispersion degree of the basal texture. The optimal comprehensive mechanical properties are obtained at the strain rate of 10 s−1, with UTS of 358 MPa, YS of 291 MPa and EL of 21.5%. Keywords  ZK60 alloy · Texture evolution · Dynamic recrystallization · Dynamic precipitates · Mechanical properties

1 Introduction Due to the close-packed hexagonal structure and the lack of slip systems, the wrought Mg–Zn system alloy is easy to form a strong {0002} basal texture in the rolling process, which brings about the anisotropy and increases the difficulty in secondary processing [1]. Therefore, how to weaken the basal texture and improve the formability have become the key to the extensive application of the wrought Mg–Zn alloy. In addition to the material composition design [2, 3], the researchers also modify the basal texture by optimizing the * Qin Wu [email protected] * Jihua Chen [email protected] 1



School of Materials Science and Engineering, Hunan University, Changsha 410082, People’s Republic of China

2



Hunan Provincial Key Laboratory of Spray Deposition Technology & Application, Hunan University, Changsha 410082, People’s Republic of China

3

State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, People’s Republic of China



rolling parameters (rolling temperature, strain rate, strain and pre-rolling treatment, etc.) [4, 5]. Hantzsche et  al. [2] have reported that the basal texture can be weakened by the addition of Ce, Nd and Y, which is related to the dynamic recrystallization (DRX) grains formed on the compression twins and the secondary twins in the deformation band. Chino et al. [3] have found that the addition Ca can inhibit the formation of the basal texture in the coldrolled