(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 湖南科技大學(xué) 機電工程學(xué)院，湘潭 411201；
3. 廣西南南鋁箔有限公司，南寧 530031；
4. 中南大學(xué) 有色金屬先進結(jié)構(gòu)材料與制造協(xié)同創(chuàng)新中心，長沙 410083)
摘 要: 以汽車車身用6061-T4鋁合金為研究對象，利用顯微硬度測試、拉伸試驗和透射電子顯微鏡(TEM)，研究溫變形對汽車車身用6061鋁合金自然時效及烤漆硬化的影響。結(jié)果表明：溫變形后的6061鋁合金不會發(fā)生明顯的自然時效效應(yīng)，放置8 d的自然時效過程中硬度值保持穩(wěn)定；對溫變形樣品分別立即和停放8 d后，實施模擬烤漆(180 ℃人工時效30 min)溫變形后立即進行烤漆，其硬化能力與放置8 d后再進行烤漆樣品的無明顯差異。合金烤漆后的硬度與溫變形溫度有關(guān)，在160~230 ℃范圍內(nèi)，隨著溫變形溫度上升，硬度上升；而經(jīng)250 ℃拉伸后，烤漆硬度出現(xiàn)下降， 230 ℃為最適宜溫度，此條件下成形后的6061鋁合金經(jīng)烤漆過程后，硬度最高值可達到114HV。
關(guān)鍵字: 6061鋁合金；溫變形；烤漆硬化；β″析出相；自然時效
（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
