Filler powder free joining of SAF 2507 using selective microwave hybrid heating technique

Abstract

Microwave Hybrid Heating (MHH) based joining of super duplex stainless steel (SAF 2507) with cross-sectionaldimensions 3.5 mm ×3 mm has been carried out for the first time by using a microwave applicator of 900 W operated at2.45 GHz for 400 s. Graphite rods have been used instead of traditionally used charcoal powder to serve as susceptormaterial. Graphite rods are good susceptor of microwave radiations therefore the presence of these rods helps in initiatingand carrying forward the joining process. Moreover, the melting temperature can be achieved for specimens underinvestigations through this novel process thereby eliminating the need of using any filler powder. Absence of filler powderreduces the process cost significantly. The joints have been mechanically characterized by Vickers micro-hardness andphysically characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) tests. It hasbeen observed through these tests that micro-hardness of the joints was more than the base alloy due to transfer of carbonfrom graphite rods to the joint zone.