(1. 河北省特种运载装备重点实验室(燕山大学)，秦皇岛 066004；
2. 先进锻压成形技术与科学教育部重点实验室(燕山大学)，秦皇岛 066004)
摘 要: 基于高强铝合金低温形变热处理工艺，研究了自然时效对AA7075铝合金力学性能的影响并使用透射电镜(TEM)对热处理后的组织形貌进行了观察。将板材试样单向拉伸与三维数字图像相关(3D-DIC)技术相结合，研究了自然时效对板材拉伸变形锯齿形屈服行为(Portevin-Le Chatelier，PLC效应)的影响，对B型、C型PLC效应时域和空域行为的相关性进行了研究；应用轮廓扫描与3D-DIC等技术手段，研究了PLC效应为对变形试样表面质量的影响机制。研究表明：随自然时效时间延长，PLC效应产生的应力锯齿和PLC变形带特征均由C型向B型转变，直至消失；变形试样表面波纹度减弱。对于PLC变形带的带静态行为，变形带作用位置随机，产生周期短，对试件表面质量的影响最大；带动态行为，PLC变形带传播引发板材表面质点产生连续、均匀的厚向位移，对表面质量影响小。
关键字: AA7075铝合金；Portevin-Le Chatelier (PLC)效应；时空演变；表面质量
（1. Hebei Key Laboratory of Special Delivery Equipment, Yanshan University, Qinhuangdao 066004, China;
2. Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education of China, Yanshan University, Qinhuangdao 066004, China）
Abstract:Based on the low temperature thermo-mechanical treatment process of high-strength aluminum alloy, the uniaxial tensile test was combined with three-dimensional digital image correlation (3D-DIC) to study the effect of natural aging on the Portevin-Le Chatelier (PLC) effect of AA7075 sheet. The temporal and spatial evolutions of deformation in the full field of specimen surface of type B and type C were observed. Contour scanning and 3D-DIC were used to study the effect of PLC effect on the surface quality of deformed samples. The results show that with the extension of natural aging time, the serrations in the stress-strain curves and PLC bands characteristics generated by PLC effect change from type C to type B until disappear; at the same time, the surface waviness of the deformed sample weakens. For the static behavior of the PLC bands, the PLC bands has a random position and short production cycle, which has a great influence on the surface quality of the specimen. For the dynamic behavior of the PLC bands, the propagation of the PLC bands causes a continuous and uniform thick displacement of the sheet surface, which has little effect on the surface quality.
Key words: 7075 aluminum alloy; Portevin-Le Chatelier (PLC) effect; temporal and spatial evolutions; surface quality
