Preparation And Properties Of Pure Copper With Different Grain Size By Multi-pass ECAP

As a widely used metal material,copper is used in electronic industry,mechanical industry,construction industry,national defense industry and other fields due to its excellent conductivity and thermal conductivity,but the strength and hardness of pure copper are not high enough.It can not meet the increasing demands of industrial production,which limits the use of pure copper.Therefore,it is valuable to improve the strength and hardness of pure copper with a reasonable method.This paper takes the commercial pure copper T2 as the research object,improves the traditional mould design scheme,the grain refinement and mechanical properties of the material are improved by multi-pass equal channel angular pressing experiment.This study investigates the effects of strain rates on the dynamic performance of pure copper with different grain size.In addition,the influence of prestrain on the mechanical properties of pure copper are also studied.The main research contents are as follows:1.In order to solve the problems of low efficiency of specimen preparation,such as the shortage of mold clamping force,the disassembling difficulties,A new mold design called symmestrical-split combined die is proposed,and multi-pass equal channel angular pressing experiment is carried out,pure copper specimens with different extrusion passes are prepared.2.The microstructure evolution,microhardness and tensile properties of pure copper with different extrusion passes are studied,the tensile fracture surface is analyzed by SEM.3.In order to study the sensitivity of pure copper with different grain size to strain rate,the rate sensitivity of pure copper with different grain size are analyzed by tensile deformation under different strain rates.4.In order to study the influence of prestrain on the mechanical properties of pure copper of different extrusion passes,the tensile pre-treatment of specimens and the tensile test are carried out.In short,in this paper,the pure copper T2 is studied based on the proposed fine grain strengthening pressing process.The traditional die design scheme is improved,and the specimens with different extrusion passes are prepared efficiently.With the increase of extrusion passes,the grain size of the sample obviously decreased,the tensile strength and microhardness of the specimans can be significantly improved.In the study of rate sensitivity,it is found that the strain rate sensitivity factor increases with the decrease of grain size.At the same time,in the study of the effect of different prestrain on pure copper,the results show that there are obvious differences in the effect of different prestrain on different samples.