LAUSR

Abstract Dissimilar lap joints for a low carbon steel (SS400) sheet with thickness of 2 mm on a 6061-T6 Al alloy sheet with thickness of 5 mm or 10 mm were created by a process called friction stir spot fusion welding (FSSFW) using an assembly-embedded rod (AER) tool under a downward force of 12 kN and a rotational speed of 1200 rpm at different dwell times. The Al alloy sheet was melted at the central area of the faying surface, so that two IMC layers were formed at this surface and identified as Fe 2 Al 5 and Fe 4 Al 13 , as detected by XRD and SEM images. The IMC thickness increased along with dwell time, but its increment rate became slower for IMC thickness larger than 25 μm. The failure load increased along with the IMC thickness, but the failure load decreased quickly for IMC thickness larger than 17 μm. It was able to achieve 18–22 kN for the thickness of the IMC layer in the range of 6–17 μm for a dwell time from 35–55 s. The larger the crack was, the smaller the failure load.