Effect Of Grain Size On Pure Copper Microrolling And Numerical Simulation Study

With the rapid development of micro system technology(MST),micro electro-mechanical system(MEMS)and medical engineering field,the market demand for micro parts is increasing,which has accelerated the rise and development of micro manufacturing industry.However,due to the influence of size effect,it is very difficult to explain the deformation behavior of the material in microforming by using the traditional plastic processing theory,which has limited the industrial production of micro forming,so it is necessary to study the size effect.In this paper,the effect of grain size on the mechanical properties of pure copper sheet under different annealing treatments is studied in the laboratory.The effects of grain size and the reduction ratio on nonuniform deformation,edge crack,microstructure and texture evolution in pure copper microrolling are studied through microrolling experiment,numerical simulation and XRD method.The main results are as follows:(1)As the grain size increases,the elongation and tensile strength of pure copper sheet decrease gradually and the number of the microvoids on the tensile fracture surface decreases significantly.(2)With the increase of grain size,the edge deformation is becoming more nonuniform,the edge bulge is more and more obvious,the uneven spread increases,the rolling force decreases gradually,the plasticity of material and rolling force are becoming more and more unstable.With the increase of reduction ratio,the edge uneven deformation increases,the edge bulge is more and more obvious,the uneven spread and the nonuniform deformation of whole workpiece increases.(3)When the reduction ratio is 80% and the grain size is 65?m,the edge cracks begin to appear,but the cracks are small.When the grain size increases to 200?m,edge cracks extend and become deep.When the grain size is 200?m and the reduction ratio is less than 60%,there is no edge crack.When the reduction ratio increases to 80%,the edge cracks start to appear.(4)In the same large deformation,the grains are elongated,microstructure becomes lamellar structure.With the increase of grain size,grains are elongated along the rolling direction;when the grain size increases to 200?m,the grain shape becomes continuous lamellar structure.When the grain size is constant,with the increase of the reduction ratio,the grains gradually are squashed and elongated,and the grain shape becomes lamellar structure along the rolling direction.(5)When the reduction ratio is 80% and the grain size is from 20?m to 65?m,the intensity of rolling texture changing slightly,the texture types do not change and show strong {112}<111>Copper texture and {123}<634>S texture.When the grain size increases to 200?m,the {112}<111>Copper texture and {123}<634>S texture become obviously weaker,and the texture type evolves into recrystallization texture.When the grain size is constant,with the increase of reduction ratio,the intensity of {112}<111>Copper and {123}<634>S texture increases,but the intensity of {001}<100>Cube texture gradually decreases.