Investigation on Microwave Joining of Mild Steel Plates at 2.45 GHz and Joint Characterization

Abstract

Microwave joining of materials is a recently developed advanced joining process in which electromagnetic energy at 2.45 GHz is used to develop butt joint between different metallic plates. Rapid selective hybrid heating of the targeted area depends upon the location of the metallic samples inside the applicator cavity during microwave exposure. A high electric field intensity location for rapid hybrid heating of samples was identified inside the resonating cavity with the help of the COMSOL Multiphysics 5.2. Accordingly, experimentation was done to develop joints of mild steel (MS) samples using microwave energy at 2.45 GHz and input power of 900 W. The nickel powder was used as an interface material between metallic plates. The fabricated mild steel butt joints were characterized to analyse the microstructures and the micro indentation hardness of the joints. The microstructural characterization of the joints revealed complete melting of nickel powder and its fusion with base mild steel plates. The presence of iron in the joint zone indicated a metallurgical fusion of the interface layer with the base metal; however, oxides and carbides presence in the joint indicated interaction with atmospheric oxygen and carbon in the susceptor. The hardness of the developed joint zone was 405 ± 12 Hv which is higher as compared to the base metals (211 ± 12 Hv).