EVALUATION OF Ni-Cr-Mo ALLOY APPLIED BY WELD OVERLAY CLADDING ON CARBON STEEL FOR USE IN NaCl 3.5% MASS SOLUTION

Abstract

This paper presents an evaluation of specimens prepared by deposition of UNS 625 alloy on carbon steel. The coating was performed using the weld process SMAW (Shielded Metal Arc Welding) to compare with a repair performed on a pressure vessel in a marine facility where severe localized corrosion occurred. The specimens were prepared by qualified welders using E-NiCrMo3 filler. Chemical analyses were performed by X-ray fluorescence to evaluate the degree of welding dilution that increases the iron content and gradually decreases the Ni-Cr-Mo contents in the coating final layer. The application of one layer the iron content was identified as 23.10% and for three layers the iron value was 2.94%. The Standards recommend a value of less than 5% iron. Corrosion and polarization tests were performed, both in NaCl solution at 3.5%, to investigate the corrosion resistance of the deposited metal mainly in relation to crevice corrosion and galvanic corrosion.