| Equal Channel Angular Pressing (ECAP) is one of the most promising techniques that has been proved to be an effective method at present, which is used to fabricate various bulk ultrafine-grain materials. During the pressing, the billet undergoes severe shear deformation by multi-pass, and could improve mechanical property of materials by only change microstructure, and the grain can be refined largely. But it is rarely reported on study and to apply scale-up ECAP to industrial production.The5N5high pure aluminum,99.97%refined aluminum and99.7%commercial pure aluminum were used as the experimental material of ECAP experiment. The effect of ECAP parameters, such as ECAP routes,passes were investigated on grain refinement systematically. For the high pure Al that dynamic recrystallization occurred, the effect of ECAP parameters were directly investigated on grain refinement through hardness and TEM analysis. For the refined Al and commercial pure Al, the microstructure variation with different passes was observed through TEM analysis, and the effect of defferent annealing conditions on grain size was investigated. Recrystallization temperature was infered through metallograph and hardness analysis. On the recrystallization annealing condition, the grain size with different ECAP parameters was compared. At last, the grain size with different purity was compared.The experimental results show that the grain refinement result of route135designed particularly was superior to traditional route Be. Because of sufficient distortion and heat, dynamic recrystallization occurred of high pure Al during the process of ECAP. The perfect recrystallization temperature of refined Al was between200℃and250℃, the perfect recrystallization temperature of commercial pure Al was between250℃and300℃. The thermal stability of pure Al was favourable. On the recrystallization annealing condition, the grain refinement result of refined Al and commercial pure Al was superior to high pure Al. |
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