纯铜纳米晶切屑的等通道转角挤压块体成形工艺

ECAP block forming process for pure copper nanocrystalline chips

通过有限元和试验相结合的方法,探究等通道转角挤压试验中挤压道次对由挤压纳米晶纯铜切屑制备的纯铜棒料所受的等效应变、挤压载荷和平均等效应力的影响规律,研究在热压协同作用下挤压道次对纳米晶细化和纳米成形块体致密性的影响。结果表明:随着挤压道次的增加,试样的平均等效应变和等效应力逐渐增大,变形区的等效应变分布的均匀性降低,试样的硬度先增大后降低;随着挤压道次的增加,在低道次(<4道次)下挤压后试样的固化成形效果越好,在高道次(>4道次)下由于挤压试样受热和高压的作用,晶粒间难以融合固结,且材料出现的孔隙和裂痕增多,试样的变形抗力下降。

The influence laws of extrusion passes on equivalent strain,extrusion load and average equivalent stress for pure copper bar prepared by extruding nanocrystalline pure copper chips in equal channel angular pressing(ECAP)test were explored by the combination of finite element and experiment,and the influences of extrusion passes on nanocrystalline refinement and compactness of nano-formed block under hot pressing synergy were studied.The results show that with the increasing of extrusion passes,the average equivalent strain and equivalent stress of sample gradually increase,the uniformity of equivalent strain distribution in the deformation zone decreases,and the hardness of sample first increases and then decreases.With the increasing of extrusion passes,the curing forming effect of sample after extrusion at low passes(<4 passes)is better.However,at high passes(>4 passes),due to the effect of heating and high pressure on extruded sample,it is difficult for grains to fuse and consolidate,the pores and cracks in the material increase,and the deformation resistance of sample decreases.