(1. 北京科技大学 材料科学与工程学院，北京 100083；
2. 辽宁科技大学 材料科学与工程学院，鞍山 114051)
摘 要: 在250~ 400 ℃温度范围内以恒温、恒应变速率(10-3 和10-2 s-1) 对铸轧AZ31 镁合金进行拉伸实验，在不同应变下研究温度和应变速率对动态再结晶的影响，探讨二相粒子对动态再结晶的影响，并分析动态再结晶机制。结果表明：当应变相同时，再结晶晶粒尺寸随温度升高而增大。中温区(200~300 ℃)动态再结晶的主导机制为连续动态再结晶，高温区(300 ℃以上)动态再结晶的主导机制为不连续动态再结晶。变形过程中破碎的Mg17Al12相粒子及钉扎在晶界处的(Al,Mn)相粒子可提高动态再结晶的形核率。在350 ℃下，当应变速率由10-3 s-1 升高到10-2 s-1 时，晶粒尺寸逐渐减小，且出现孪生再结晶。
关键字: AZ31 镁合金；铸轧；动态再结晶
（1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;
2. School of Materials Science and Engineering, University of Science and Technology Liaoning, Anshan 114051, China）
Abstract:Tensile tests were conducted for a twin-roll cast AZ31 alloy under constant temperatures (250-400 ℃) and constant strain rates of 10-3 and 10-2 s-1, aimed to study the effects of temperature and strain rate on dynamic recrystallization at different strains, to explore the effects of the second phase particles on dynamic recrystallization, and to analyze the mechanisms of dynamic recrystallization. The results show that the grain size of the recrystallized grains increases with temperature under the same strain. The continuous dynamic recrystallization dominates at the intermediate temperature range (200-300 ℃), while the discontinuous dynamic recrystallization dominates at high temperatures (over 300 ℃) . The fractured Mg17Al12 particles and the (Al, Mn) phase particles pinning at grain boundary can improve the nucleation rate of dynamic recrystallization. When the strain rate increases from 10-3 s-1 to 10-2 s-1 at 350 ℃, the grain size gradually decreases, and the twin recrystallizaiton occurs.
Key words: AZ31 magnesium alloy; twin-roll cast; dynamic recrystallization
