Effects of Annealing and Solution Treatment on Microstructure and Tensile Properties of 7001 Aluminum Alloy Tube

• Main Authors: Yu-TingLi, 黎寓庭
• Other Authors: Li-Hui Chen
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/46nce3

碩士 === 國立成功大學 === 材料科學及工程學系 === 103 === 7001 aluminum alloy tube has higher strength but lower ductility in Al-Zn-Mg-Cu alloy system. Heat treatments are conducted to improve formability before plastic process. Annealing―415℃/2h→260℃/2h→RT(by furnace cooling) and solution treatment―490℃→RT(by water quenching) were used in this study. Microstructure observation by OM and SEM, phase analysis by XRD and DSC, and tensile tests were done. Properties of parallel and vertical to extrusion direction were investigated respectively. As the results showed, microstructure (alignment of particles and texture) affected the tensile properties, but no obvious difference of tensile properties between two directions. After annealing, Al matrix became soft and second phases particles remained, which caused low strength and high ductility. The major fracture mode was ductile fracture, and dimple distributed throughout the fracture surface. After solution treatment, most second phases dissolved into matrix, leading to supersaturated state of material. During deformation, it showed high work hardening rate and exhibited larger uniform elongation than annealing treated one, and it ruptured in shear fracture mode. As a whole, solution treatment had a bigger benefit of improving formability before plastic process.