Mechanical properties of steel-aluminum multi-materials using a structural adhesive

Abstract

In this study, a DP590 steel sheet and A356 cast aluminum alloy were joined using a structural adhesive to evaluate the effect of the mechanical behavior depending on the adhesion strength. The tensile test results of the steel-aluminum multi-materials showed that the elongation of aluminum prior to fracture tends to increase with increasing adhesion strength. SEM observations of the tensile specimen fracture surface in A356 single material showed cracks that propagated along the interface of the eutectic Si phase and Al phase. On the other hand, the multi-materials tended to produce considerable deformation inside the primary Al due to the uniform dispersion of stress throughout the joint surface. Bending under the same stacking sequence conditions of multi-materials, the flexure stress increases until interfacial separation because of the uniform deformation of different materials as the adhesion strength increases. In addition, the results of bending on the steel (upper) - aluminum (lower) condition showed interfacial separation and aluminum. This was attributed to aluminum with weak ductility under a tensile load, which resulted in fracture. On the other hand, in the case of the aluminum (upper) - steel (lower) condition, the multi-materials act like a single material, so that the aluminum did not break until the end of the test.