半固态轧制对沉积态7050铝合金显微组织的影响

Effect of Semisolid Rolling on Microstructure of Deposited 7050 Aluminum Alloy

在560～620℃下对喷射沉积态7050铝合金材料进行了半固态轧制实验,采用扫描电镜和能谱仪、X射线衍射仪考察了材料晶粒尺寸和第二相粒子的分布随重熔温度的变化规律,以及轧制过程中重熔温度和变形量对带材显微组织的影响,分析了半固态轧制的可行性.结果表明:喷射沉积态7050铝合金的晶粒长大激活能为70.5kJ/mol;当重熔温度由560℃增加到620℃时,材料的晶粒粗化速率由1.16μm3/s增加到76.06μm3/s,液相分数由3.7%增加到64.1%;第二相粒子的分布和数量对晶粒的粗化有抑制作用;喷射沉积态7050铝合金最佳的半固态轧制重熔温度为590℃;喷射沉积态材料在半固态轧制成形时,形变的主要作用是致密化材料、破碎晶粒、促使动态再结晶的发生.

Semisolid rolling of spray-deposited 7050 aluminum alloy was carried out at 560 - 620 ℃, and the effects of remehing temperature on grain size and second-phase distribution of the alloy were investigated by means of SEM, EDS and XRD. Moreover, the influences of remelting temperature and thickness reduction ratio on the microstructure of the strips were explored, and the feasibility of semisolid rolling was evaluated. The results show that （1） the activation energy for the grain growth of spray-deposited 7050 aluminum alloy is 70. 5 kJ/mol; （2） when the remelting temperature increases from 560 to 620 ℃, the coarsening rate and the liquid fraction of spray-deposited 7050 aluminum alloy respectively increase from 1.16 to 76.06μm^3/s and from 3.7% to 64. 1% ; （3） the distribution and amount of second-phase particles inhibit the coarsening of spray-deposited 7050 aluminum alloy; （4） the optimum remelting temperature for the semisolid rolling is 590 ℃ ; and （5） the rolling deformation plays its role in terms of eliminating pores, breaking grains and accelerating dynamic recrystallization.