Evaluation of modal characteristics of SS202-SS202 lap joint produced using selective microwave hybrid heating

Microwave joining is an upcoming technique of joining similar and dissimilar materials. Different metals, non-metals, alloys, and ceramics have already been joined successfully in the past. However, the joining of long bulk metals is always challenging and an impediment in commercial exploitation of microwave joining methods. Lap joints on SS202 specimens of dimensions 160 × 31 × 1 mm have been fabricated using selective microwave hybrid heating inside a domestic microwave oven of 2.45 GHz frequency and 700 W power, using nickel as an interface material. Exposure time has been varied from 15 to 25 min. A modified crucible setup has been proposed for better masking during the heating process. To establish a microstructure property correlation, the joint zone has been characterized using electron microscopy and energy dispersive spectroscopy (EDS). Microhardness tests as well as shear test has also been carried out on joined specimens. Further, experimental modal analysis has been carried out to measure the dynamic or modal characteristics of the joined specimens and to characterize the various modal parameters like, natural frequencies, mode shapes, and corresponding structural damping present in the microwave welded structure. Exposure time of microwave hybrid heating is observed to influence the damping characteristics as well as other properties of the joined specimens. An optimum exposure time of 19 min has been observed for producing good quality joints.