Mechanical properties and formability of metal–polymer–metal sandwich composites

Mechanical properties and formability of a three-layer metal–polymer–metal sandwich composite were studied as a function of the angle of the sample axis with respect to the rolling direction. Sandwich was obtained by bonding a polymer core, 0.4 mm in thickness, between two steel sheets, each of them with a thickness of 0.2 mm. The strength-deformation characteristics and anisotropic behavior were investigated by performing uniaxial tensile tests. Hemispherical punch tests were also carried out in order to evaluate both formability, in terms of limiting dome height and forming limit curves, and thinning attitude of the metal–polymer–metal sandwich composite. Finally, the fracture surfaces of both tensile and hemispherical punch-formed samples were analyzed by means of the scanning electron microscopy. It was observed that the samples oriented at 45° to rolling direction are characterized by the highest mechanical properties and formability as compared to the ones at 0° and 90°. Such results were related to the debonding mechanism occurring at the interfaces between steel sheet and plastic core as the angle of the sample axis was 0° and 90°.