Formation mechanism and control of aluminum layer thickness fluctuation in embedded aluminum–steel composite sheet produced by cold roll bonding process

The influences of rolling reduction and aluminum sheet initial thickness (AIT) on the thickness fluctuation of aluminum layer (TFA) of embedded aluminum–steel composite sheet produced by cold roll bonding were investigated, the formation mechanism of TFA was analyzed and method to improve the thickness uniformity of the aluminum layer was proposed. The results showed that when the reduction increased, TFA increased gradually. When the reduction was lower than 40%, AIT had negligible effect on the TFA, while TFA increased with the decrease of AIT when the reduction was higher than 40%. The non-uniformities of the steel surface deformation and the interfacial bonding extent caused by the work-hardened steel surface layer, were the main reasons for the formation of TFA. Adopting an appropriate surface treatment can help to decrease the hardening extent of the steel surface for improving the deformation uniformity during cold roll bonding process, which effectively improved the aluminum thickness uniformity of the embedded aluminum/steel composite sheets.