چكيده به لاتين
The purpose of this study was to investigate the effect of heat treatment and severe plastic deformation on the microstructure and mechanical properties of AA6063 aluminum alloy. In this regard, the prepared samples after initial annealing (550oC - 6h), were cooled to room temperature in different environments, i.e., in the furnace, air and water. Subsequently, all of the samples were subjected deformed via equal channel angular pressing (ECAP) and were aged at 150oC for 8 hrs. Different cooling rates were found to have no effect on the microstructure. Deformation led to decrease in the grain size to be continued with increasing the number of ECAP passes. Water-quenched samples (WQ) showed more significant grain refinement during ECAP which was diminished after 6 passes. The increase in dislocation density after 2 passes ECAP was higher for WQ samples rather than the air-cooled (AC). This trend was continued up to six passes. With further deformation, the dislocation density was continued to increase for the AC samples while it was reduced for WQ. After aging heat treatment, there was a noticeable drop in dislocation density in all samples. By increasing cooling rate, the strength and hardness of the samples increased. In case of AC sample, an increase in strength was associated with decreased ductility, while increasing the strength of the WQ sample with preservation of ductility. By increasing the number of deformation passes to 10 on furnace-cooled (FC) and AC samples, a significant increase in strength and decreased ductility of the alloy was resulted. However, in the case of WQ sample, with increasing deformation up to 6 passes, the strength increased, but with the continuation of the deformation, the strength decreased. Applying aging treatment on the deformed AC and WQ samples, led to the decrease in strength. For WQ samples, Unlike the AC samples, the strength reduction was not associated with increased ductility. A similar trend was observed in the hardness of the samples.