Strengthening and stress drop of ultrafine grain aluminum after annealing
(1. School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 200126, China;
2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)
2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: Ultrafine grain pure aluminum was produced by equal channel angular pressing and cold rolling, the deformed aluminum was annealed at 200 °C for 1 h. The tensile curves of deformed and annealed aluminum show that yield strength of deformed aluminum increases by 100%−300% and its elongation decreases by about 20%. After low temperature annealing, strength of annealed aluminum increases by 20% and elongation decreases by over 50%, the recovery of dislocations may be the main cause of annealing strengthening. In addition, there is an abrupt stress drop in the tensile curves of annealed aluminum and the formation of shear band is responsible for it.
Key words: aluminum; ultrafine grain; mechanical properties; heat treatment