Study On Deformation Of Pure Copper Strip During Continuous Extrusion By Using Finite Element Simulation

Grain refinement is an important way to promote the comprehensive properties of metals.As an effective method to refine the grain and improve the property of metals,severe plastic deformation(SPD)has attracted much attention by scholars all over the world in the field of materials science and engineering.However,there still exist some difficulties in processing long ultrafine grained(UFG)strips,let alone the production in a large scale.In this thesis,numerical simulations are used to give a systematic analysis of pure copper strip deformed on an improved continuous extrusion equipment.The deformation behavior of pure copper strip under this new deformation way will be made clear,which will be helpful to further improvement of the equipment.The continuous equal thickness extrusion of pure copper strip has been simulated by using finite element method.The effect of such parameters as deformation passes,pressures exerted by planetary rolls and die parameter,etc.,on the deformation stability,the deformation characteristics and microstructural evolution of the pure copper strip.It can be shown from this study that the channel angle of the die for the improved continuous extrusion method should not be less than 115 degrees.It is better placing a guide plate between planetary roll 1 and 2 to avoid the strip from bending.The optimal condition for the improved continuous extrusion of copper strip is 120 degrees of the channel angle and 2500N of spring pressure to one-side of a planetary roll,which can ensure a multi-pass deformation of copper strip without failure.Metal strips of yield strength less than 100MPa should not be processed in this extrusion deformation.A stable deformation condition was obtained for continuous extrusion of metal by the study in this thesis.A model was established on the basis of dislocation theory for the prediction of grain size.The calculated results of the grain refinement for pure copper strip in continuous extrusion is reasonable and well consistent with the experimental.The work of this thesis is of great value for further improvement of the continuous equal thickness extrusion technology.It is also of practical value for the research on the control of grain refinement as well as this new processing method.