(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 湖南科技大学 机电工程学院，湘潭 411201；
3. 广西南南铝箔有限公司，南宁 530031；
4. 中南大学 有色金属先进结构材料与制造协同创新中心，长沙 410083)
摘 要: 以汽车车身用6061-T4铝合金为研究对象，利用显微硬度测试、拉伸试验和透射电子显微镜(TEM)，研究温变形对汽车车身用6061铝合金自然时效及烤漆硬化的影响。结果表明：温变形后的6061铝合金不会发生明显的自然时效效应，放置8 d的自然时效过程中硬度值保持稳定；对温变形样品分别立即和停放8 d后，实施模拟烤漆(180 ℃人工时效30 min)温变形后立即进行烤漆，其硬化能力与放置8 d后再进行烤漆样品的无明显差异。合金烤漆后的硬度与温变形温度有关，在160~230 ℃范围内，随着温变形温度上升，硬度上升；而经250 ℃拉伸后，烤漆硬度出现下降， 230 ℃为最适宜温度，此条件下成形后的6061铝合金经烤漆过程后，硬度最高值可达到114HV。
关键字: 6061铝合金；温变形；烤漆硬化；β″析出相；自然时效
（1. School of Material Science and Engineering, Central South University, Changsha 410083, China;
2. College of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
3. Alnan Aluminium Inc., Nanning 530031, China;
4. Nonferrous Metal Advanced Structure Material and Manufacture Collaborative Innovation Center,
Central South University, Changsha 410083, China）
Abstract:The effects of warm deformation on natural ageing and mechanical property of aluminum alloy 6061 for automotive body were investigated by microhardness test, tensile test and TEM. The results show that no obvious natural aging effect is found in the warm deformed samples, and the hardness maintains stable during the 8 d natural ageing after warm deformation. Simulated baking process, i.e., artificial ageing at 180 ℃ for 30 min, is conducted to the warm deformed samples immediately and after a delay of 8 d, respectively, and no obvious mechanical property difference is found between the two groups of samples. The hardness of the samples is deformation temperature dependent, i.e., it increases with the increasing of warm deformation temperature within the range of 160-230 ℃, but further increasing of deformation temperature to 250 ℃ leads to the decrease of final hardness. 230 ℃ is the optimum warm deformation temperature, and the final hardness of the samples deformed at this temperature increases to 114HV.
Key words: 6061 aluminum alloy; warm deformation; paint-bake hardening; β″ precipitates; natural ageing
