Mechanical behavior and void coalescence analysis of cryorolled AA8090 alloy

Aluminum lithium alloy was rolled at two different temperatures, viz., 28 °C (301 K) and −196 °C (77 K). The thickness of the alloy was reduced by 75 % from its initial thickness (6 mm) in each condition. X-ray diffraction analysis was carried out on all samples to determine the grain size and dislocation density. The cryorolled sample exhibited a finer grain size with higher dislocation density, which was evidenced from micrographs obtained with transmission electron microscopy. Electron backscattered diffraction images revealed the presence of bimodal grain distribution in the rolled samples, in which the cryorolled sample exhibited a larger amount of ultrafine grains. Both tensile and hardness tests were performed on rolled samples. Cryorolled samples showed superior properties when comparing with room temperature rolled sample. Scanning electron microscopic images of fractured samples were used to analyze the void coalescence behavior. The various void coalescence parameters like void size, void area, length to width ratio of void, and ligament thickness were analyzed, and these results were correlated with microstructure, mechanical properties, crystallite size, and dislocation density in all conditions.