High Strain Rate Electromagnetic Crimping on a Variation of Impact Target Geometry

Abstract

Due to its lightweight and high-strength-to-weight ratio, the demand for aluminum alloy AA6061 in automotive and aerospace industries necessitates robust joining with similar and dissimilar materials. Electromagnetic crimping (EMC) is a high-speed and contactless material joining process. This study investigates the effect of target rod surface geometry on the crimping of AA6061 tubes onto AA6061 rods. Experiments were performed at a discharge energy of 6.34 kJ by changing the target rod surface geometry to threading, knurling, grooving, and a plain finish. Samples were crimped with a multi-turn Archimedean spiral coil and a double taper field shaper for steady and concentrated magnetic pressure. Threaded rods showed higher load-bearing strength than knurled, grooved, plain finish samples under pullout, and compressive shear loading. Further, cross-sectional analysis was performed to get insights about material flow and deformation mechanisms. A microhardness test was conducted to understand the flyer and target material deformation behavior under high strain rate conditions. This study demonstrates that threaded surface geometry on the target rod significantly enhances EMC joint strength. In contrast, target rods with knurled surface geometry demonstrate higher hardness near the crimp interface due to more impact points and local strain-hardening effects. © ASM International 2025.