Maximum residual contact stress in spinning process of SS304/20 bimetallic pipe

During forming process of the bimetallic pipe, the residual contact stress between the pipes is one of the most important technical issues. In recent study, the bimetallic pipe was manufactured by internal spinning forming technology and analyzed via different theories of elasto-plastic mechanics. It was assumed that the maximum contact stresses generated between the pipes when the inside surface of the outer pipe expanded to the elasto-plastic interface position. In addition, the maximum value of the residual contact stress occurred when the spinning pressure unloaded. The theoretical model of the elasto-plastic zone and the elasto-plastic boundary position of the outer pipe during the spinning process was proposed. The validity of the proposed model was verified by finite element simulation and experimentation, and the experimental results are in good agreement with those obtained from simulation. The obtained test results exhibit that the new technology is feasible and can be provided a theoretical reference for industrial applications.