Effect of a Cold Wire on the Metallurgical Characteristics of Nickel-Based Welds Deposited by GMAW-CW

摘要

This paper aims to study the solidification structure of Ni-based superalloy class AWS ER NiCrMo-4 metallic coatings deposited by GMAW and gas metal arc welding-cold wire (GMAW-CW) processes with two heat input levels (0.9 and 0.6 kJ mm(-1)) on carbon steel plates. The metallurgical characterization of the coating's interface was performed by scanning electron microscopy, optical microscopy, and electronic dispersion spectroscopy. Mechanical evaluation was carried out by Vickers hardness test. The results revealed that the welding conditions did not influence the solidification structure (planar, columnar, and equiaxed); however, molybdenum microsegregation to interdendritic region was observed. Cold wire addition by GMAW-CW process decreased the iron dilution on weld metal, but increased the partially mixed zone thickness and hardness values. The increase in heat input produced the opposite behavior to the cold wire feeding.