Effect of the arc energy on microstructure and corrosion resistance on Inconel 625 weld overlays deposited by GMAW process

Inconel 625 alloy is a highly corrosion resistant nickel-based alloy, largely used as coatings onto a less noble substrates Many techniques have been used for the deposition of Inconel, including welding processes. Traditionally, welding processes that promote low dilution (less contamination of Inconel with the substrate material) have been used, but they present low productivity due to the low deposition rates involved. Thus, this study aims to evaluate the application of Inconel 625 using the GMAW process under different arc energies, which should lead to high deposition rates, but with the inconvenience of promoting high dilution. For this, coatings were deposited using three levels of arc energies and the effects on microstructure and corrosion resistance were evaluated. The macro and microstructural characteristics of the deposited were evaluated by optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Dilution and secondary dendrite arm spacings were measured and microstructures were evaluated. The corrosion resistance of the deposits was evaluated via cyclic potentiodynamic polarization tests. The results showed that the relationship between arc energy and dilution depended on the weaving amplitude. The arc energy affected the amount of phases, where lower energies produced more refined dendritic structures. In addition, the study showed that corrosion tests conducted at 25 degrees C did not promote superficial corrosion in the samples regardless of the arc energy imposed on the coating and that the tests at 60 degrees C caused corrosion.