(1. 湖南科技大學(xué) 高功效輕合金構(gòu)件成形技術(shù)及耐損傷性能評(píng)價(jià)湖南省工程研究中心，湘潭 411201；
2. 寧波大學(xué) 機(jī)械工程與力學(xué)學(xué)院，寧波 315211；
3. 湖南工學(xué)院 汽車零部件技術(shù)研究院，衡陽 421002)
摘 要: 對(duì)鑄態(tài)AZ31鎂合金進(jìn)行溫度300~400 ℃、平均應(yīng)變速率5.4~29 s-1的高應(yīng)變速率軋制，制備不同孿晶和晶粒尺寸分布的鎂合金板材，研究孿晶及晶粒尺寸分布對(duì)鎂合金高應(yīng)變速率軋制板材強(qiáng)韌化的影響，并建立了多尺度組織的強(qiáng)韌化模型。結(jié)果表明：平均應(yīng)變速率低于10 s-1時(shí)，可以獲得孿晶、細(xì)晶和粗晶共存的多尺度組織，且平均應(yīng)變速率為8.3 s-1時(shí)，組織中存在大量的亞微晶；在室溫變形過程中，不同尺度組織之間的背應(yīng)力能夠保證材料塑性，孿晶界和細(xì)晶保證強(qiáng)度，實(shí)現(xiàn)亞微晶、細(xì)晶、孿晶和粗晶共存的多尺度組織鎂合金具有高的抗拉強(qiáng)度，同時(shí)能夠保持相對(duì)良好的伸長率；在高溫變形過程中，亞微晶、細(xì)晶、孿晶和粗晶共存的多尺度組織鎂合金中的亞微晶發(fā)生晶界滑動(dòng)、粗晶和孿晶誘導(dǎo)再結(jié)晶提高了材料塑性；溫度為300 ℃變形時(shí)，強(qiáng)度亦遵循Hall-Patch公式。
關(guān)鍵字: AZ31鎂合金；多尺度組織；亞微晶；孿晶；背應(yīng)力
（1. Hunan Engineering Research Center of Forming Technology and Damage Resistance Evaluation for High Efficiency Light Alloy Components, Hunan University of Science and Technology, Xiangtan 411201, China;
2. Faculty of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, China;
3. Research Institute of Automobile Parts Technology, Hunan Institute of Technology, Hengyang 421002, China）
Abstract:Aiming to produce magnesium alloy sheets with different distributions of twin and grain size, the high-strain rate rolling was carried out on as-casting AZ31 magnesium alloys at temperatures of 300-400 ℃ and average strain rates of 5.4-29 s-1. The effects of twin and grain size distribution on the strengthening and toughening of high-strain rate rolled magnesium alloy sheets were studied. The strengthening and toughening model was also established. The results show that when the strain rate is lower than 10 s-1, the multi-scale microstructure including twin, fine grain and coarsen grain can be obtained and majority submicro-grains appear at an average strain rate of 8.3 s-1. During room temperature deformation, the back stress between different scale grains leads to good plasticity, and the twin boundaries and fine grains result in high strengthen. Then, high strengthen and relatively good plasticity are obtained in magnesium alloy with multi-scale microstructure including submicro-grain, fine grain, twin and coarsen grain. During high temperature deformation, the occurrence of grain slide in submicorgrain, the onset of dynamic recrystallization inside coarsen grains and twin induced dynamic recrystallization cause the plasticity improvement in magnesium alloy with multi-scale microstructure including submicro-grain, fine grain, twin and coarsen grain. At a deformation temperature of 300 ℃, the strengthen still obeys the Hall-Patch equation.
Key words: AZ31 magneisum alloy; multi-scale microstructure; submicrograin; twin; back stress
