Forming limit diagrams of fine-grained Al 5083 produced by equal channel angular rolling process

Abstract

The objective of this research is to study the strain forming limits of Al–Mg alloy (5083) sheet, fabricated by equal channel angular rolling process at room temperature. For this purpose, the equal channel angular rolling process was executed at room temperature in three passes. Mechanical properties, microhardness, and microstructure were investigated after the equal channel angular rolling process. Uniaxial tensile tests of the equal channel angular rolling process produced samples and showed that yield and ultimate stresses increase, while the uniform elongation to fracture decreases in comparison with the annealed state. There was a continuous hardness enhancement by increasing the number of the equal channel angular rolling passes. After the third pass, the amount of hardness raised by 73% in comparison with the annealed sample. In the fourth pass, the hardness reduced slightly, that was attributed to the strain saturation in room temperature and was followed by high surface cracks. In the annealed condition, the average grain size was 45 µm, and after the third equal channel angular rolling pass, this amount was reduced to 10 µm. Furthermore, the forming limit diagrams were determined experimentally, using the Nakazima test. The obtained results show that after the third pass, the forming limit diagrams’ level move downward, meaning that a reduction occurred in the forming limits of equal channel angular rolled samples.