MECHANICAL AND MICROSTRUCTURAL PROPERTIES OF THE INCONEL 625 ALLOY WELD OVERLAYS OBTAINED BY ELECTROSLAG WELDING PROCESS
Francisco Carlos Albuquerque Madalena1; Camila Pereira Alvaraes2; Luis Felipe Guimarães de Souza2; Jorge Carlos Ferreira Jorge2; Leonardo Sales Araujo3
1 Petrobras; 2 CEFET-RJ; 3 UFRJ
doi:10.20906/CPS/COB-2015-0592
Resumo
Nickel base weld overlays are commonly used in oil & gas industry to extend the life of equipments under aggressive corrosion environments, since the overlays improve the corrosion resistance without a significant increase the cost of manufacture when compared to massive equipment. Usually, the joints are welded by SMAW, GMAW or GTAW processes. In this respect, the electroslag welding process (ESW), which promotes high heat inputs and low dilution welds, can be an interesting option for this application as provides a high productivity. The present work evaluates mechanical, microstructural and corrosion properties of an Alloy 625 weld overlay deposited on ASTM A516 Grade 70 carbon steel by electroslag welding process (ESW), in as welded and heat treated conditions. Bending and microhardness tests were conducted, in order to verify possible effects of welding thermal cycle on the mechanical properties. Microstructural evaluation was performed using both optical (OM) and scanning electron microscopy (SEM) techniques. Corrosion tests were conducted on samples removed from top layer of weld overlay cladding deposit according to ASTM G 48 Method A Standard. Low dilution rates and the microhardness values for all regions studied were within the requirements of the standards. Corrosion tests showed no evidences of pitting. All results obtained with this welding process were considered satisfactory.
Palavras-chave: overlay; inconel 625; electroslag