Abstract: Laminated steel is a new type of composite material in the field of metal packaging. The interfacial bond strength and water permeability of the finished laminated steel depend on the thickness and flow-spreading behavior of the molten layer of the polymer film during the laminating process. However, it is difficult to tune the thickness of the molten layer and its flow-spreading behavior, because the laminating process is complex and rapid, and affected by the microscopic topography of the substrate surface. Aiming at this difficulty, the microscopic topography of the substrate surface was characterized and reconstructed based on the fractal theory, the viscoelastic constitutive relation of the polymer film was established based on the generalized Maxwell model experiment, hence a finite element simulation model of the laminating process considering the microscopic topography of the substrate was established, and the accuracy of the model was experimentally verified. The model results show that the thickness of the molten layer is mainly affected by the initial preheating temperature of the substrate strip, and the interface filling ratio is mainly affected by the pressure of the laminating roll. The molten layer thickness and the interfacial filling ratio increase with the decrease of the roughness of the substrate strip and the increase of the initial preheating temperature of the substrate strip and the laminating roll, and the increase of the roll pressure also leads to the increase of the interfacial filling ratio. These laws were quantitatively described, which provides a theoretical basis for fine-tuning the thickness of the molten layer and its flow-spreading behavior.

Key words: laminated steel, interface heat transfer, melting-filling, preheating temperature, microscopic morphology, laminating roll stress