Performance of the INCONEL 625 alloy weld overlay obtained by FCAW process

Resumo

Nickel-based weld overlays (cladding) are commonly used in oil & gas industry to extend the life of equipment
under corrosive environment, as it improves the corrosion resistance without a significant increase in
the manufacturing cost, when compared to a full nickel-based alloy equipment. Although there are extensive
literature involving overlays applied by SMAW, GMAW or GTAW processes, works about the use of
FCAW process are limited. Consequently, an investigation of the performance of the overlays deposited by
this process, which provides a higher productivity in comparison to the processes usually used, can be an
interesting option for this application.
The present work evaluates the mechanical and microstructural properties of the nickel-based superalloy 625
weld overlay deposited on a ASTM A516 Grade 70 carbon steel plate by the flux cored arc welding process
(FCAW), both in as welded and heat treated conditions. Bending and microhardness tests were performed in
order to verify possible effects of welding thermal cycles on the mechanical properties. The microstructure
was evaluated through both optical (OM) and scanning electron microscopy (SEM), with the use of electron
backscatter diffraction (EBSD) technique. Corrosion tests were conducted on samples removed from the top
layer of the weld overlay according to ASTM G 48 Method A. All results obtained with this welding process,
in both as welded and heat treated samples, were considered satisfactory.
Keywords: Clad; Inconel 625; FCAW; post weld heat treatment.