【摘要】 等通道转角挤压工艺(ECAP)通过不同路经的多道次挤压变形,产生大的塑性变形,可以达到细化晶粒的目的,同时也是超细晶材料制备的一种有效渠道。但试样在通过转角处会产生强烈的拉应力,累积的拉应力极易达到材料的抗拉极限,导致开裂,甚至断裂。为了减少这一现象发生的几率,减小试样开裂倾向,便于后一道次的挤压,对转角为90°的模具进行了改进。对2A12铝合金进行挤压研究结果表明,在C路径下4道次挤压效果较好,增强了晶粒细化效果,伸长率最大提高了10.3%,硬度最大提高了46.4%。更多还原

【Abstract】 Equal channel angular pressing(ECAP),as one of the most effective methods for producing ultra-fine grain materials(UFG),whose principle is that through pressing the billet in the die with two channels intersecting at an angle repeatedly,high shear strain is imposed on the sample,and thus the grain size is refined.However,experiments show that cracking or fracture usually occurs in the vicinity of upper surface of the extruded specimen even only after a few passes with conventional die(90°).The tensile stress occurs in the vicinity of upper surface of the specimen in the severe plastic deformation zone,which increases the crack and fracture tendency of the specimen and impedes the further ECAP processing.2A12aluminum alloy was tested by ECAP.The results reveal that in the Crouth four passes,extruding effect exhibits desirable,and the grain refinement is improved,where elongation is increased by 10.3%,and maximum hardness is increased by 46.4%.更多还原