Effects of the Replacement Vanadium to Niobium at E347-16 Electrode on Micro-structure and Corrosion Behaviors of Weld Metal

In this research, effects of the replacement vanadium to niobium at E347-16 electrode on microstructure and corrosion behaviors of weld metal have been studied. For this reason, two types of electrodes have been produced with ferrovanadium and ferroniobium containing at the coat of the electrodes. Specimens were welded by SMAW according to AWS A5.4, then the samples were cuts and prepared from the weld metal for the chemical analysis, corrosion test and metallographic examination. The result of the chemical analysis test and matching with the schaeffler diagram indicated that the micro-structure of the weld metals was composed of the ferrite and austenite. The the metallographic examination results indicated that the weld metal of the electrode containing vanadium had a higher volume percentage of ferrite than that the electrode containing niobium. Also, the results of corrosion tests showed that with replacing vanadium to niobium at the E347-16 electrode, susceptibility of the intergranular corrosion was at the acceptable range, and the resistance to pitting corrosion was not significantly affect, as well as the electrochemical behavior of the weld metals is not that much difference. The final results determined that the replacement of vanadium to niobium at the E347-16 electrode is possible to metallurgical standpoint.