Research on the Forming Process of Bimetal Composite Pipe by Hydroforming

Bimetal composite pipe has higher strength and is more corrosion and high temperature resistant compared to single metal pipe, making it a new type of pipe that is being gradually applied to important industrial fields such as aviation and aerospace manufacturing. To study the hydraulic forming mechanism of bimetal composite pipes, the forming process is divided into three stages: liner pipe elastic–plastic deformation, base pipe loading, and unloading. The stress and strain relation between the liner and base pipe during the gradual increase in hydraulic pressure is analyzed, and the range of selected internal pressure required for composite pipe formation and the relation between residual contact pressure and internal pressure for the liner–base pipe interface are obtained. The accuracy of analytical predictions for the contact pressure and the axial and circumferential strains on the outer wall of the base pipe during the forming process is verified through numerical simulation and composite pipe forming experiments. Through this analysis, the appropriate internal pressure for forming can be selected and the residual contact pressure between the layers can be effectively regulated to ensure quality formation of composite pipes, depending on different materials and working conditions. Effective guidance for production practices can be provided by theoretical analysis and numerical simulation during the development of bimetal pipe composite process.