Mechanical properties and interface failure behavior of steel/Al laminated composite sheets during tensile test

The tensile tests of steel/aluminum composite sheet were conducted at strain rate ranging from 1×10-4 s-1 to 1×10-2 s-1. It was aimed to study the deformation behavior and failure mechanism. The results show that a transition layer with thickness of about 8 μm and a few of intermetallic compounds Fe2Al5 and Fe4Al13 phases forms at the steel/aluminum roll-bonded interface. The strength of the composite sheet satisfies the mixing rule with the individual layers. The interface plays an important role in the strengthening of composite sheet. However, the bonding interface is prone to fracture due to microstructural defects. The failure of the interface and the strain hardening of the individual layer cause the stress-strain curve to fluctuate. High strain rate loading leads to the sharp break of interface layer and the obvious fluctuation of tensile curve. During the quasi-static tensile process, the cracks firstly initiate in the steel/aluminum interface, and the additional stress between the layers causes the cracks to grow and expands into aluminum layer. The steel layer subsequently necks and causes the composite sheet to fracture. By increasing the bonding strength of steel/aluminum interface, the deformation coordination and mechanical properties of the composite sheets can be improved. © 2021, China Science Publishing & Media Ltd. All right reserved.