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

Microwave Hybrid Heating (MHH) based joining of super duplex stainless steel (SAF 2507) with cross-sectional dimensions 3.5 mm x3 mm has been carried out for the first time by using a microwave applicator of 900 W operated at 2.45 GHz for 400 s. Graphite rods have been used instead of traditionally used charcoal powder to serve as susceptor material. Graphite rods are good susceptor of microwave radiations therefore the presence of these rods helps in initiating and carrying forward the joining process. Moreover, the melting temperature can be achieved for specimens under investigations through this novel process thereby eliminating the need of using any filler powder. Absence of filler powder reduces the process cost significantly. The joints have been mechanically characterized by Vickers micro-hardness and physically characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) tests. It has been observed through these tests that micro-hardness of the joints was more than the base alloy due to transfer of carbon from graphite rods to the joint zone.