In this paper

through the combination of the finite element numerical simulation and the actual test

the causes of the surface groove formation of superplastic forming/diffusion bonding (SPF/DB) four-sheet structure are analyzed and studied. The orthogonal test method is used to analyze the influence of four factors on the surface groove of the panel

including the strain rate έ

the diffusion connection width b

the thickness ratio t of the core plate to the panel and the friction coefficient u of the die. It can be seen that the thickness ratio t of the core plate to the panel is the most important factor of the surface groove of the panel. Based on the experimental study

a method of pressing 0.2MPa back pressure on the panel surface is proposed

which can effectively control the formation of the surface groove of SPF/DB four-sheet structure.