Investigations on joining of CRNO electrical steel with and without susceptor using microwave energy

Microwave hybrid heating (MHH) has not been applied to joining thin laminated sheets of Cold Rolled Non-Oriented (CRNO) electrical steel. This study transforms microwave-metal repulsion into effective steel joining, utilizing CRNO electrical steel powder (ESP) and Blumer 1450XX as filler material. The study explores separate agglomeration of CRNO-ESP, as well as butt and lap joint formation. Investigations with and without susceptor (green silicon carbide [SiC] and charcoal powder) and separator (graphite sheet) of various thicknesses has been carried out using graphite and charcoal crucibles. Joints are investigated using optical and scanning electron microscope (SEM) analysis, energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD). Optimal results are observed in joints of thin sheets using CRNO-ESP (1.00 g) and Blumer 1450XX (0.60 g). A 9% hardness improvement in the material processed in charcoal crucible is observed with 360 s of heating using susceptor and separator, and 390 s without prior arrangement. Negligible material composition change and no phase change with (110), (200) and (211) hkl ferrite reflection indices through XRD analysis was observed. The study and issues during joining CRNO electrical steel sheet (ESS) could be helpful for industrial material processing to prevent changes in material properties after joining.