Microstructure and mechanical properties of Al-Mg-Si alloy U-shaped profile
(1. Manufacturing Center, Zhuzhou CRRC Times Electric Co., Ltd., Zhuzhou 412001, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China)
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China)
Abstract: To get a full understanding of hot extrusion, solid solution treatment and aging process on the Al-0.56Mg- 0.63Si alloy, the microstructure and mechanical properties of a U-shaped profile were studied through optical microscopy, scanning electrical microscopy, transmission electrical microscopy, hardness, and tensile tests. The coarse equiaxed grains existed near the profile edge as a result of the dynamic recrystallization nucleation and exceeding growth during hot extrusion. The fibrous deformed and sub-structured grains located between the two coarse grain layers, due to the occurrence of work-hardening and dynamic recovery. Perpendicular needle β′′ precipitates were distributed inside the grain, and obvious precipitates-free zone appeared after aging treatment. The tensile strength, yield strength and elongation of the aged Al-Mg-Si alloy U-shaped profile were no less than 279.4 MPa, 258.6 MPa, and 21.6%, respectively. The fracture morphology showed dimple rupture characteristics. The precipitates and grain boundaries played key role in the strengthening contribution.
Key words: Al-Mg-Si alloy; U-shaped profile; hot extrusion; microstructure; mechanical properties; precipitates