The Comparison between SMAW and FSW Performances on Microstructure, Hardness and Corrosion Susceptibility of Carbon Steel

Corrosion tends to occur at various rates in the base metal, heat affected zones (HAZ) and the weld or fusion metal. The corrosion rate of API X52 carbon steel by Shielded Metal Arc Welding (SMAW) and Friction Stir Welding (FSW) were investigated using Linear Polarization Resistance (LPR) test. The microstructure of the base metal, HAZ and weld metal for SMAW and FSW were studied using optical microscope. The hardness values for both SMAW and FSW on carbon steel were determined using Rockwell Hardness Test. The optical microscope test results indicated that for both SMAW and FSW, the grain size decreases starting from the base metal to the HAZ, followed by the weld metal. The hardness test results showed that the weld metal yields highest hardness values, while the base metal yields lowest hardness values. In conclusion, SMAW exhibited higher hardness values compared to FSW. The LPR test results showed that for both SMAW and FSW, the weld metal has the highest corrosion susceptibility as compared to the HAZ and base metal. In addition, FSW weldment was more susceptible to corrosion than SMAW.