Development of ultrafine-grained Al 6063 alloy by cryorolling with the optimized initial heat treatment conditions

The effects of rolling temperature and rolling strain on the microstructural refinement of Al 6063 alloy are investigated in the present work by employing electron back scattered diffraction (EBSD) analysis, transmission electron microscope (TEM) investigations, and X-ray diffraction (XRD) analysis. The solution treated bulk Al 6063 alloy samples are subjected to cryorolling and room temperature rolling to produce sheets with different strain levels such as 0.4, 2.3 and 3.8, respectively. Prior to cryorolling and room temperature rolling, the initial conditions such as solution treatment temperature, and sample immersion duration time, in liquid nitrogen, before cryorolling are optimized by using EBSD analysis, TEM investigations, hardness test, and tensile test. It is observed that the formation of recrystallized ultrafine-grains with the high angle grain boundaries occurs at the strain value of 3.8. However, in case of room temperature rolled samples, the sub-grains are not recrystallized even up to the strain value of 3.8. (C) 2010 Elsevier Ltd. All rights reserved.