Ductility Improvement of an AZ61 Magnesium Alloy through Two-Pass Submerged Friction Stir Processing

Author： Luo Xicai Cao Genghua Zhang Wen Qiu Cheng Zhang Datong

Publisher： MDPI

E-ISSN： 1996-1944|10|3|253-253

ISSN： 1996-1944

Source： Materials, Vol.10, Iss.3, 2017-03, pp. : 253-253

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Abstract

Friction stir processing (FSP) has been considered as a novel technique to refine the grain size and homogenize the microstructure of metallic materials. In this study, two-pass FSP was conducted under water to enhance the cooling rate during processing, and an AZ61 magnesium alloy with fine-grained and homogeneous microstructure was prepared through this method. Compared to the as-cast material, one-pass FSP resulted in grain refinement and the β-Mg₁₇Al₁₂ phase was broken into small particles. Using a smaller stirring tool and an overlapping ratio of 100%, a finer and more uniform microstructure with an average grain size of 4.6 μm was obtained through two-pass FSP. The two-pass FSP resulted in a significant improvement in elongation of 37.2% ± 4.3%, but a slight decrease in strength compared with one-pass FSP alloy. Besides the microstructure refinement, the texture evolution in the stir zone is also considered responsible for the ductility improvement.