深冷处理对汽车轮毂用A356铝合金组织与力学性能的影响

Effects of Cryogenic Treatment on Microstructure and Mechanical Properties of A356 Aluminum Alloy for Automobile Hub

对A356铸造铝合金进行了530℃×4 h固溶+不同时间深冷+160℃×6 h时效处理,采用显微组织观察、拉伸试验、硬度测试等研究了不同时间深冷处理对A356铸造铝合金组织与性能的影响。结果表明:铸态A356铝合金的组织由树枝状α-Al相和共晶硅相组成,合金经固溶+时效处理后树枝晶有所长大。合金经固溶+1 h深冷+时效的A356树枝晶明显细化,共晶硅相分布均匀,深冷时间增加到8、16 h时,合金中硅相逐渐偏聚,晶粒逐渐粗化。随着深冷时间的增加,合金试样的硬度、抗拉强度先升高后降低,伸长率先升高后降低又小幅度升高,A356铝合金经固溶+1 h深冷+时效处理后综合力学性能最佳。

A356 cast aluminum alloy was treated by 530 ℃× 4 h solid solution and different time cryogenic treatment and160 ℃× 6 h aging treatment, and the effects of different time of cryogenic treatment on the microstructure and mechanical properties of A356 cast aluminum alloy were studied by means of microstructure observation, tensile test and hardness test.The results show that the microstructure of cast A356 aluminum alloy is composed of dendrite α-Al phase and eutectic silicon phase, and the dendrite grows after solution and aging treatment. After solution and 1 h cryogenic and aging, the dendrites of A356 alloy are obviously refined, and the eutectic silicon phase is evenly distributed. When the time of cryogenic treatment increases to 8 h and 16 h, the silicon phase in the alloy is gradually segregated and the grains are gradually coarsened. With the increases of cryogenic time, the hardness and tensile strength of the alloy samples first increase and then decrease, and the elongation first increases and then decreases and then increases slightly. The comprehensive mechanical properties of A356 aluminum alloy treated by solution and 1 h cryogenic and aging are the best.