## 2 Materials and Methods
### Electrochemical Corrosion Testing  
The corrosion testing methods for the specimens included hydrogen collection measurement, electrochemical testing, and hydrogen bubble detection. The specimens for the corrosion testing were divided into two types. The first type was cut from the weldment samples at the three zones of interest and ground with abrasive papers up to 2000 grit, and the second type used resin and was mounted in a container for electrochemical testing and recorded for video. The first type was applied to hydrogen collection and electrochemical testing and the second type targeted hydrogen bubble quantification.  
Sodium molybdate (Na\({}_{2}\)MoO\({}_{4}\)) in powder form (22.3 wt% Na, 46.6 wt % Mo, and O 31.1 wt %) was dissolved into a 1 M HCL electrolyte solution. The solution will act as a corrosion test solution with varying concentrations of 0 g/L, 0.1 g/L, 0.2 g/L, 0.3 g/L, and 0.4 g/L.  
A range of corrosion testing solutions were prepared with various percentages of sodium molybdate, Na\({}_{2}\)MoO\({}_{4}\) inhibitors, i.e., 0.1, 0.2, 0.3, and 0.4 g/L, into 1 M HCl. The electrochemical test methods were performed by potentiodynamic polarization with an Autolab potentiostat (PGSTAT 128N, Herisau, Switzerland). A three-electrode system was used for conducting the PP test, with the weldment specimen as the working electrode as shown in Figure 2a. The reference electrode was Ag/AgCl (3 M KCl), and the counter electrode was platinum. The PP test was measured at +/ - 1 V from the corrosion potential (E\({}_{\text{corr}}\)) at a scan rate of 1 mV/s. Then, the Tafel plot extrapolation was analyzed by using the software tool associated with the potentiostat NOVA 1.11.  
The inhibition efficiency IE (%) of the inhibitor was calculated by using the equation below:  
\[IE(\%)=\frac{i_{corr}-i_{corr(inh)}}{i_{corr}}\]  
where i\({}_{corr(inh)}\) and i\({}_{corr}\) are the corrosion current densities with and without the inhibitor, obtained by the extrapolation of the Tafel lines to the corrosion potential from the PP test.  
Figure 2b shows the minicell was linked to the three-electrode cell within the solutions contained in the specimen container [6]. After closure, it was directed toward a 50 mL  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Values** \\ \hline Current Type & DC \\ Polarity & DCEP (Direct Current Electrode Positive) \\ Current (A) & 90 \\ Electrode Type & E6013 \\ Arc Voltage (V) & 24 \\ Travel Speed (mm/min) & \(\pm\)150 \\ Electrode Angle (degrees) & \(\pm\)45 \\ Arc Length (mm) & 3-8 \\ Type of Butt Welds & Double-V butt joints with single pass each side \\ Groove Angle (degrees) & 60 \\ Butt Gap (mm) & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 1: SMAW process parameters.  
springer designed for dissolved gas analysis (DGA) (Figure 2b), as well as to the solutions. This configuration was employed to quantify the volume of H\({}_{2}\) gas generated during the PP test.  
Three techniques--potentiodynamic polarization, hydrogen volume measurement, and deep learning--were employed using five specimens. Each test specimen underwent evaluation in distinct types of HCl solutions: HCl + SM 0 g/L, SM 0.1 g/L, HCl + SM 0.2 g/L, HCl + SM 0.3 g/L, and HCl + SM 0.4 g/L. Additionally, each specimen underwent five repetitions for the respective tests.