中文摘要：

通过力学性能检测、扫描电镜和透射电镜观察，研究了3种工艺下大冷变形对2024铝合金组织和性能的影响。结果表明，大冷变形后2024铝合金的伸长率随时效时间的延长呈台阶式变化，当时效时间≤40min时，δ5≥8％；时效时间≥160min时，伸长率急剧降低，δ5约为2％。研究表明，伴随S′相析出所产生的晶界无析出带及粗大的晶界平衡相，是2024铝合金伸长率急剧降低的主要原因。

英文摘要：

The effects of severe cold plastic deformation of three testing process on the microstructure and elongation of the 2024 aluminum alloy were investigated by means of mechanical tensile test,SEM and TEM observations. The results show that the elongation （ δ5 ） of the alloy is larger than 8% when the aging time is less than 40 min,and markedly decreases rapidly from 8% to 2% when the aging time is more than 60 min, displaying platform with the prolonging of aging time in the age-elongation curve. It is suggested that the formation of precipitation free zones accompanying with the precipitation of S＇phase and coarsen equilibrium phase （S） on the grain boundaries reduce the elongation.