Influence of Welding in Operational Conditions on the Partial Mixed Zone Formation in Ni-Based Dissimilar Weld Overlay

The main objective of this study, was to evaluate some of the operational conditions on the partial mixed zones with martensite formation in the fusion boundary of nickel-based alloys weld overlays, deposited by the GTAW cold wire feed on C-Mn steel plates. The Taguchi method was applied. Furthemore, control factors duly investigated, were of the type from nickel-based alloys, a type of shielding gas, in heat input level, a type of arc oscillation and the microstructure was investigated as well, using light microscopy, scanning electron microscopy (SEM), energy dispersive of X-ray spectroscopy (EDS), bacicscattering electron diffraction (EBSD). The coating bond and microhardness tests were carried out to evaluate some mechanical properties. The results showed that the global dilution level of the weld overlay, does not have any influence on the PMZ content. However, the interface coating/substrate were influenced by the operational conditions and the formation of PMZ with martensite was mainly influenced by the heat input level, shielding gas and arc oscillation, which are strongly related to the amount of metal deposited per unit length and the melted pool agitation.