Fabrication of fine-grained, high strength and toughness Mg alloy by extrusion-shearing process
(1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;
2. Key Laboratory of Magnesium Alloys and Processing Technology of Liaoning Province, Shenyang 110870, China)
2. Key Laboratory of Magnesium Alloys and Processing Technology of Liaoning Province, Shenyang 110870, China)
Abstract: A novel extrusion-shearing (ES) composite process was designed to fabricate fine-grained, high strength and tough magnesium alloy. The structural parameters of an ES die were optimized by conducting an orthogonal simulation experiment using finite element software Deform-3D, and Mg-3Zn-0.6Ca-0.6Zr (ZXK310) alloy was processed using the ES die. The results show that the optimized structural parameters of ES die are extrusion angle (α) of 90°, extrusion section height (h) of 15 mm and inner fillet radius (r) of 10 mm. After ES at an extrusion temperature and a die temperature of 350 °C, ZXK310 alloy exhibited good ES forming ability, and obvious dynamic recrystallization occurred in the forming area. The grain size decreased from 1.42 μm of extrusion area to 0.85 μm of the forming area. Owing to the pinning of second phase and formation of ultrafine grains, the tensile strength, yield strength and elongation of alloy reached 362 MPa, 289 MPa and 21.7%, respectively.
Key words: Mg-Zn-Ca-Zr alloy; extrusion-shearing process; die design; dynamic recrystallization; mechanical properties