Microstructure investigation and mechanical property analysis in electromagnetic riveting

Electromagnetic riveting (EMR) is a new joining technology based on high-speed magnetic impulse forming and conventional riveting. EMR experiments were conducted on dual-layered 2A12 aluminum alloy sheets with one 2A10 aluminum alloy rivet. Observation of the microstructure and mechanical properties of rivet heading verified the forming quality of the heading. And, mechanical property tests were performed to evaluate the durability of riveted specimens through shear and pull-out loading. Microstructure observation indicated that adiabatic shear bands, where the deformation was highly concentrated, were an important characteristic of deformed structures in rivet headings under electromagnetic riveting. The distribution law of hardness in rivet headings was obtained. The compressive yield strength of rivet headings increased 70 % over that of the original rivets. Riveted specimens were capable of withstanding shear loads of 23.2 kN and pull-out loads of 35 kN. Ruptures characterized by a scanning electron microscope were found to be due to shear failure.