Microstructure and Properties Evolution of 7075 Al Alloy in Hot Rolling and Short Process Heat Treatment

Abstract

7075 aluminum alloy is widely used in the aerospace field because of its low density, high specific strength, high fracture toughness, and good machinability. Herein, the evolution of the microstructure and properties of 7075 aluminum alloy at different temperatures is systematically studied. Based on the rolling and heat treatment process, a short process of rolling and heat treatment is proposed, which can significantly improve the properties. The study finds that the nanophases are distributed in a “streamline‐like” or “lip‐like” shape after rolling. When the rolling temperature is below 550 °C, the phases are mainly Al7Cu2Fe, the grain size does not change significantly, and shear bands appear inside the grains. When rolled at 600 °C, the grains coarsen significantly and the shear bands become longer, resulting in overburning and cracking. The broken phases are smoothed when rolled at 550 °C. It is observed that the nanophases becomes larger. Due to the strain‐strengthening effect, the ultimate tensile strength increases by 6% with little change in elongation. In industrial production, direct aging treatment after high‐temperature rolling can reduce energy consumption and improve production efficiency.