Effect of Annealing on Mechanical Properties and Metallurgical Factors of Ultrafine-Grained 6082 Al Alloy

In the present work, cryorolling (CR) (rolling temperature is - 196 degrees C) followed by annealing (AN) (100-400 degrees C for 1 h) of 6082 Al alloy has been performed. The main objective of this study was to investigate the thermal stability of the ultrafine-grained 6082 Al alloy, for higher temperature applications. The mechanical properties of the CR and the CR + AN 6082 Al alloy were investigated and correlated with the microstructure with the help of a transmission electron microscope (TEM). The hardness and the tensile strength of the CR + AN (150 degrees C) 6082 Al alloy were significantly improved up to 95% and 40%, respectively, when compared to the solution-treated (ST) 6082 Al alloy. The main reason behind the mechanical strength improvement was dislocation strengthening and precipitation strengthening. Thermal stability of the CR 6082 Al alloy was found up to a high annealing temperature of 300 degrees C due to the pinning of grain boundaries by precipitates evaluation during annealing by Zener drag effect. The formation of beta ''-phase, beta '-phase and stable beta-phase occurred at the annealing temperatures of 175 degrees C for 1 h, 200 degrees C for 1 h and 250 degrees C for 1 h, respectively.