Experimental Investigation of Heat Treatment Effects on Mechanical Properties and Microstructure of AA6063 Alloy in ECAP Process

Abstract

Severe Plastic Deformation (SPD) methods have gained significant attention in modern metal forming due to their ability to create desirable microstructures. One highly regarded SPD method is Equal Channel Angular Pressing (ECAP), which induces substantial shear strain to refine grains during the forming process and subsequent recrystallization. Numerous factors influencing ECAP's efficiency and material quality have been subjects of extensive research. This study investigates the effects of various heat treatment cycles on the mechanical properties and microstructure of 6063 AA alloy subjected to ECAP. The ECAP process was performed up to 4 passes at room temperature, following the BC route for aluminum samples of 6063 AA. Additionally, the combination of ECAP and in-passe aging heat treatment was examined. To evaluate the mechanical properties and microstructural changes, tensile and hardness tests along with Scanning Electron Microscopy (SEM) were utilized. Results indicated a significant increase in strength and hardness, coupled with a reduction in elongation, attributed to work hardening and grain refinement. SEM images confirmed ECAP's effectiveness in producing ultrafine grains. Overall, natural aging for 30 days post-ECAP showed no effect on mechanical properties compared to immediate solutionizing and subsequent ECAP. For applications requiring high strength and substantial elongation, artificial aging post-ECAP is recommended.