Investigation of the bonding strength of the stainless steel 316L/polyurethane/stainless steel 316L tri-layer composite produced by the warm rolling process

In this study, a metal/polymer tri-layer composite was produced by direct adhesion (without adhesive), and mechanical locks were created using the warm rolling process. The effect of the process parameters including preheating temperature, rolling speed, thickness reduction, surface roughness, and the orientation of the surface scratches on the bond strength between layers was investigated. The results indicated that the suitable polymer fluidity and penetration, to provide stronger mechanical locks and higher bond strengths, could be achieved at an optimum preheating temperature and a rolling speed of 240°C and 36 r/min, respectively. In addition, the most appropriate surface pretreatment was obtained in the wire brush in the rolling direction mode with the surface roughness of 0.65 µm, so that the failure mechanism in this case was cohesive and the optimum thickness reduction was achieved at 40%. Furthermore, the mechanical properties of the sandwich sheet with highest bonding strength were evaluated.