Improving strength of Al-7075 by applying severe plastic deformation (SPD) leads to a drop in material ductility. The challenge of the present study is to achieve both strength and ductility improvement in Al-7075 by a combination of dual equal channel lateral extrusion (DECLE) and aging heat treatment. The design of experiment (DOE) was also used to obtain the first-order polynomial equations in order to examine the effect of DECLE and aging statistically. To improve both strength and ductility, the specimen was first subjected to one pass of DECLE at 400 °C and then subsequent aging heat treatment at the temperatures of 120 °C and 150 °C for 9 and 24 h. It was found by analysis of the polynomial equations that the combination of one pass of DECLE process and aging heat treatment at 150 °C for 24 h led to the notable improvement of 63.5% in yield strength, 41.2% in ultimate strength and 20% in elongation. Besides, DECLE process was determined to be the most influential factor for improving the strength and deteriorating the ductility. Micrographs of optical microscope (OM) and scanning electron microscope (SEM) showed that elongated grains were formed by DECLE process, and precipitations were crushed into finer ones and distributed along the extrusion direction. Fracture surface analysis depicted that after employing both DECLE process and aging heat treatment, number of fine dimples increased and distributed uniformly across the fracture surface.

中文翻译：

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通过将双等通道横向挤压与时效热处理相结合来提高 Al-7075 的强度和延展性

通过施加严重的塑性变形 (SPD) 来提高 Al-7075 的强度会导致材料延展性下降。本研究的挑战是通过双等通道横向挤压 (DECLE) 和时效热处理的组合来提高 Al-7075 的强度和延展性。实验设计 (DOE) 也用于获得一阶多项式方程，以便从统计上检查 DECLE 和老化的影响。为了提高强度和延展性，试样首先在 400°C 下进行一次 DECLE，然后在 120°C 和 150°C 的温度下进行 9 小时和 24 小时的时效热处理。通过多项式方程分析发现，1道DECLE工艺与150℃时效热处理24小时相结合，显着提高了63。屈服强度为 5%，极限强度为 41.2%，伸长率为 20%。此外，DECLE工艺被确定为提高强度和劣化延展性的最大影响因素。光学显微镜（OM）和扫描电子显微镜（SEM）的显微照片表明，DECLE工艺形成了细长的晶粒，沉淀物被粉碎成更细的颗粒并沿挤压方向分布。断口分析表明，采用DECLE工艺和时效热处理后，细小凹坑的数量增加并均匀分布在断口上。光学显微镜（OM）和扫描电子显微镜（SEM）的显微照片表明，DECLE工艺形成了细长的晶粒，沉淀物被粉碎成更细的颗粒并沿挤压方向分布。断口分析表明，采用DECLE工艺和时效热处理后，细小凹坑的数量增加并均匀分布在断口上。光学显微镜（OM）和扫描电子显微镜（SEM）的显微照片表明，DECLE工艺形成了细长的晶粒，沉淀物被粉碎成更细的颗粒并沿挤压方向分布。断口分析表明，采用DECLE工艺和时效热处理后，细小凹坑的数量增加并均匀分布在断口上。