Experimental & theoretical investigation of roll bonding process of multilayer strips by finite element method

In the present study, cold roll bonding process of dissimilar bimetal strips of steel/Al was simulated and investigated using finite element method. To this end, velocity variable was introduced to ABAQUS using UVARM subroutine. Accordingly, prediction of the starting bonding point by the finite element method, based on the criterion of equal velocities of the layers, was in good agreement with the experimental results. In the process of roll bonding of bimetal steel/aluminum strips, the effect of some factors on the bonding strength including the total deformation of the strip, the initial thickness of the strip, the yield stress ratio and the thickness ratio of the layers were studied. In addition, the deformation of each of the steel and the aluminum layers were also investigated during the rolling. The results of finite element simulations, as well as the experimental results, showed that with increasing the total deformation percentage of the strip, the rolling force, the mean pressure at the interface of the layers, the deformation percentage of each layer and the relative bonding length increase. Furthermore, it was found out that increasing the yield strength ratio of the aluminum layer to the steel layer at a certain total deformation percentage of the strip, on one hand, increased the rolling force, the mean pressure at the interface of the layers as well as the relative bonding length and on the other hand, decreased the non-homogeneity in the deformation of the layers. Further studies revealed that decreasing the initial strip thickness at a certain total deformation percentage of the strip reduced the rolling force as well as the non-homogeneity in the deformation of the layers. But it increased the mean pressure at the interface of the layers as well as the relative bonding length. In this regard, the unprecedented consistency of the theoretical and experimental results indicated an appropriate accuracy of the presented finite element analysis in analyzing the cold roll bonding process.