# Effect of Welding Parameter on the Corrosion Rate of Underwater Wet Welded SS400 Low Carbon Steel
## 2 Experimental Configurations  
The material used in this study was SS 400 steel which was widely applied to marine construction. The specimen size was 100 mm \(\times\) 100 mm \(\times\) 3 mm. SS 400 steel is low carbon steel that has a carbon content of 0.05%. The electrodes used were E7016, RB 26 and RD 26 type rutile underwater electrodes with a diameter of 3.2 mm waterproof and protected by wax. The underwater welding process was carried out in the water with a depth of 2.5 m, 5 m and 10 m in the experimental pond using the SMAW welding process. The results of underwater welding are to be compared with ground welding. The welding parameters used in the welding process are electric currents 100 A and 110 A. During an observation in one setting, e.g., water depth. Other parameters, e.g., voltage and current, will be set to be a constant value. Electrodes in this study are selected based on market availability with consideration to the existing range that can be used to weld thin plates with a certain thickness. According to the WPS (welding procedure specification), the lower current limit for low carbon steel plates with a thickness of 3 mm is 100 A. If welding is carried out with a current lower than 100 A, the arc is unstable, and the weld results will have a low penetration. Conversely, the upper limit of the current is 110 A, because if it is welded with a current higher than 110 A, the plate will experience holes. Practically, the three electrodes are often used in welding underwater carbon steel materials, and technically they can substitute one another. However, the technical review of underwater welding is limited to its acceptance of the standards used such as AWS which reviews physical and mechanical properties. The physical properties are in the form of welding defects and appearance of the welding campus, while the mechanical properties consist of tensile, bending and impact strength. Chemicalproperties in the form of corrosion are not a requirement for acceptance of the welded joints, so the effect of these types of electrodes on corrosion has not been investigated. According to the results of this study, electrode selection recommendations can be added to the corrosion resistance requirements. The corrosion testing method used for this test was the three-electrode polarization resistance method to determine the surface corrosion rate of welded joints. As a comparison, corrosion tests on the results of ground welds were also carried out. Illustration of cutting and dimensions of the specimen is as shown in Figure 1. Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) tests were carried out to see the type of corrosion that occurred and the distribution of chemical composition of intermetallic matrix and particles. Corrosion test using VersaStudio 2.50.3 software (AMATEK, Inc., Berwyn, US) and VersaSTAT 4 hardware (AMATEK, Inc., Berwyn, US). This test was carried out with a range of \(-0.25\) V to \(0.2\) V against corrosion potential (\(E_{corr}\)) and a scan rate of \(2\) mV/s. As a comparison, corrosion tests are also carried out on the ground welding results. Corrosion testing is carried out by scanning V values by rotating the potentiodynamic in stages and obtaining voltage (V) and current (A) data, then plotted in the E-I graph. From this graph plot obtained Tafel constants for anode and cathode in the form of graph slope and corrosion current (\(I_{corr}\)) which is in the way of the intersection of the two Tafel constants. The corrosion rate is expressed by the formula:  
\[CR=\frac{0.1288\ I_{corr}(EW)}{\rho} \tag{1}\]  
\(CR\) is the corrosion rate in miles per year (mpy) which will be converted into mmpy (millimeters per year), \(0.1288\) is a factor constant in mpyg/uAcm, \(I_{corr}\) is the current density in uA/cm\({}^{2}\), \(\rho\) is the density in g/cm\({}^{3}\).