In recent years, industrial applications of composite sheets have been increasingly expanded due to their extremely different properties such as high strength, low density, and good corrosion resistance compared to single layer sheets. For this reason, in the current study, it is investigated the flanging of composite metal sheets. Also, the behavior of an aluminum-copper sheet, cladded using explosive welding, during incremental forming of a circular collar have been experimentally and numerically studied. In addition, the experimental results are used to validate the numerical simulation of the forming process. At first, in order to understand collar forming of the perforated sheet, the effect of hole diameter, forming direction or layer arrangement on dimensional accuracy, thickness distribution and forming force were investigated and then, the effect of hole flanging and collar forming were compared using two strategies. The results show that by decreasing the initial hole diameter of sheet, the average vertical maximum force increases by 9%, the minimum thickness decreases and its location shifts toward the center of sheet. Aluminum-copper arrangement also experiences a 7% reduction in average force and a 4% increase in minimum thickness due to the protective property of copper layer in tensile state compares to copper-aluminum. Besides, the multi-step method leads to a 6% minimum thickness increase due to better material flow compared to single-step method.