Effect of ECAP and Subsequent Annealing on Microstructure, Texture, and Microhardness of an AA6060 Aluminum Alloy

AA6060 aluminum alloy was subjected to severe plastic deformation through equal-channel angular pressing (ECAP) up to 8 passes via route B-C. ECAPed samples isochronally annealed for 1 hour at a temperature range of 150-450 degrees C. The microstructure and texture of the studied material were evaluated by electron backscatter diffraction, and the microhardness was characterized by Vickers microhardness testing. It was found that shearing texture is typically enhanced after ECAP processing. Grain size and grain growth kinetics were also studied. ECAP led to a substantial rise in hardness, with stability following 4 passes. Microstructures and material properties were relatively stable up to annealing temperatures of 150 degrees C. Some sub-micrometer grains were kept in the 8 passes sample to annealing temperatures of 300 degrees C. Annealing at elevated temperature resulted in a reduction in hardness leading to a rise in grain size and a decrease in dislocation density. After annealing temperature up to 450 degrees C, the texture index reveals a tendency to the texture weakening and randomization. The activation energy required for the grain growth of the AA6060 alloy was exceptionally low above 300 degrees C.

Automated summary

After ECAP processing, AA6060 aluminum alloy showed a substantial increase in hardness, with stability improving with the number of passes. Grain size and growth kinetics were affected, and annealing temperature had an impact on material properties and structure, leading to reduced hardness and increased grain size at higher temperatures.