Microstructural Characterization of Inconel 625 Nickel-Based Alloy Weld Cladding Obtained by Electroslag Welding Process

This work investigates the microstructure and mechanical characteristics of the Inconel 625 weld cladding deposited by the ESW process with a single layer on ASTM A516 Gr. 70 steel plate with a heat input of 11.7 kJ/mm. Microhardness testing and metallographic examination were performed on samples removed transversally from the weld deposit. Metallographic characterization was performed by optical, scanning, and transmission electron microscopy and by electron backscattering diffraction. Energy-dispersive spectrometry was also used to evaluate the composition of the secondary phases. Metallographic examination of the austenitic weld metal was carried out at locations 1 mm and 3 mm from the fusion line. The results revealed that in addition to the absence of partially diluted zones, the austenitic microstructure of the weld metal contains low volume fractions of secondary phases for all conditions. So, it can be inferred that the ESW process can be an important alternative for overlaid Inconel 625 weld layers, because adequate results were achieved even only 1.0 mm from the fusion line. This may offer a useful cost reduction because the welding layer is thinner.