Mechanical testing of steel/aluminium–silicon interfaces by pushout

The functionality of structural light alloy castings can be improved by inserting into them, upon moulding, local iron base reinforcements. To acquire a better knowledge of such bimetallic assemblies, samples were prepared by immersing a mild steel bar (5 mm in diameter) in aluminium base Al–Si alloy melts held at 730 °C. After melt solidification, the bimetallic samples were cut into 5 mm thick slices and pushout testing was performed on these slices. Characterization of damaging corresponding to different load level before complete debonding allows the determination of the failure mode. Crack initiation occurs at the specimen bottom face in the intermetallic reaction layer, important damage occurs before complete debonding and no brittle failure is observed. The results highlight the necessity of analysing pushout tests with a more integrated approach taking into account shear stress distribution along the interface such as interfacial crack growth.