Finite element analysis and experimental investigation of the hydrostatic extrusion process of deforming two-layer Cu/Al composite

A concave die with an equal-strain contour line was used in the hydrostatic extrusion process to deform the two-layer Cu/Al composite. The extruding process was simulated using the finite element method (FEM). The effect of the friction coefficients on the relative slippage of the contact surfaces between the internal and external metals was investigated, and the stress distribution in the extruded specimen was studied. The simulation results reveal that the relative slippage decreases with increasing friction coefficient at the contact surface of the two metals. However, the relative slippage increases rapidly with increasing friction coefficient at the contact surface between the specimen and die. No axial tensile stress appears in the plastic deformation zone near the axis, indicating that the inner fracture will not occur in internal metal in the hydrostatic extrusion process as the concave die with equal-strain contour lines is used. The experimental test reveals that the metallurgical bond is formed between Cu and Al when the friction coefficient at the surface between the two metals is 0.3 and the extrusion ratio is 12.