Numerical Simulation On Indirect Extrusion Of Copper Clad Aluminum Bimetal Composite

Copper clad aluminum bimetal composite material, combining the advantages of copper and aluminum, possess comprehensive performance than any one of them, which has aroused great concern in the field of materials. Because of the thickness distributions of the cladding layer along the length direction are not uniform during conventional extrusion, this paper adopts the indirect extrusion method to prepare the copper clad aluminum bimetal composite material. Isothermal compression tests of pure copper T2 and 5005 aluminum alloy were performed on Gleeble-3500 system in the temperature range of 300?500? and strain-rate range of 0.01?10s-1. Finite element numerical simulation software DEFORM-2D was used to analyze the indirect extrusion of copper clad aluminum bimetal composite material. The main results are shown below:(1)Within the experimental range, pure copper T2 and 5005 aluminum alloy belong to the negative temperature sensitive material and positive strain-rate sensitive material. In the early stage of compression deformation, the flow stress increases rapidly with the increasing of the deformation degree. Subsequently, the flow stress decreases with the increasing of deformation temperature and increases with the increasing of strain rate.(2)Based on isothermal compression experimental data, the flow stress of pure copper T2 and 5005 aluminum alloy can be represented by the general ??? relationship and Zener-Hollomon parameter in the hyperbolic sine equation, their constitutive equations are:?=425.726?0.158?0.032e-0.0013T and ?=51.281n{(Z/1.37×1012)1/7.81+[(Z/1.37×1012)2/7.81+1]1/2}.(3)The finite element numerical simulation analyses show that:in the indirection extrusion forming of copper clad aluminum, extrusion pressure is gradually increased in the process of the billet filled with cavity. At the moment of billet flowing out of the die, extrusion pressure surges instantly. With the extrusion process, extrusion pressure tends to be stable during steady extrusion stage; The billet deformation is the largest at the exit of the extrusion die, and the rest is not involved in the plastic deformation; The maximum effective stress and the maximum effective strain both change in the position of the contact between the billet and the extrusion die; Under the influence of the heat exchange, the plastic deformation work and the friction heat effect, the billet temperature is on the upward trend along the radius direction.(4)Extrusion force and distribution of coating material for products the reasonable process parameters can be obtained by analyzing the effect of die angle, extrusion temperature and extrusion speed during the indirection extrusion process. The reasonable process parameters(die angle 45°, extrusion temperature 350? and extrusion speed 5mm/s)were obtained, under which the coating layer thickness distribution is most stable. The relationship between coated billet thickness ratio and the cladding layer thickness ratio was also verified in this condition. Linear fitting was used to obtain the linear equation of the percentage of cladding billet of the total billet and the percentage of coating layer thickness of the total thickness of the bimetal composite materials:y=0.00864x+20.90103.