SPIF of Cu/Steel Clad Sheet: Annealing Effect on Bond Force and Formability

Clad sheet metals offer a better combination of different properties than a monolithic sheet does. In the present study, the formability of a cold bonded Cu/Steel clad sheet was investigated in single point incremental forming (SPIF). In order to relieve deformation stresses, the sheet was annealed over a range of temperature and time. It was found that the sheet ductility increases as the annealing temperature increases, and as a result the formability increases. On the other hand, the bond force at the interface of constituent sheets was observed to decrease with the increasing of temperature. Moreover, the annealing time was found to have no significant effect both on the formability and bond force. Therefore, performing annealing for low times can satisfactorily serve the purpose. The most appropriate annealing temperature for maximizing the formability was 700°C, because higher temperature was noticed to cause severe delamination of Cu layer, thus deteriorating the clad sheet. As a promising aspect of the study, there was no delamination of laminates during forming till the maximum achievable angle. The correlations presented herein study can act as guideline for the users. This study is the first report of its nature.