Influence of Quenching Transfer Time on the Mechanical Properties and Microstructure of A357 Aluminum Alloys
FAN Zhenzhong1, ZHENG Weidong1, ZHANG Xianfeng1, LI Hong2, WANG Shaohua1
1. Beijing Institute of Aeronautical Materials, China Aviation Industry Corporation, Beijing 100095, China;
2. Schol of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
Abstract：In the present work, the effects of quenching transfer time on the mechanical properties and microstructure of A357 aluminum alloys are investigated by using optical microscopy (OM), scanning electron microscope (SEM), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), as well as tensile mechanical properties testing methods. The results show that with the increase of quenching transfer time from 3 s to 49 s, the tensile strength, yield strength and elongation of A357 aluminum alloys are reduced from 351 MPa, 275 MPa, and 12.4% to 320 MPa, 254 MPa, and 6.5% , respectively after T6 heat treatment, together with a continuous declining of tensile strength, tiny variation of yield strength and a continuous variation of elongation. The average length and width size of silicon particles are 10~25 μm and 5~10 μm, respectively, and the morphologies of neonatal and eutectic silicon particles evolve from needle and lamellar structures to spheroidal and rod structures after the T6 heat treatment process. Silicon particles are shown as needle and lamellar mostly when the quenching transfer time exceeds 35 s. The tensile fracture morphology is observed as dimple and intergranular fracture, and the intergranular fracture is increased with the prolonged quenching transfer time. Magnesium and silicon elements are distributed nearby the grain boundaries and the binary and ternary eutectic structures, whereas the aluminium elements are concentrated in the grain and grain boundaries. The length and width size of Mg2Si phase are 0.2~1 μm and 0.02~0.08 μm, respectively, the precipitation amount and size ratio of Mg2Si phase are declined, together with the decreases of strength and ductility of A357 aluminum alloy with the prolonged quenching transfer time.
樊振中, 郑卫东, 张显峰, 李红, 王少华. 淬火转移时间对A357 铝合金力学性能与微观组织的影响[J]. 科技导报, 2014, 32(32): 22-27.
FAN Zhenzhong, ZHENG Weidong, ZHANG Xianfeng, LI Hong, WANG Shaohua. Influence of Quenching Transfer Time on the Mechanical Properties and Microstructure of A357 Aluminum Alloys. Science & Technology Review, 2014, 32(32): 22-27.
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2014, Vol. 32 
