## 2 Materials and Methods  
Two bars of different metal were joined using the CDW process to form Dissimilar Metal Welds (DMWs). The metals were steel and brass. Their composition can be seen in Table 1 and their properties are listed in Table 2. Both materials are solid rod with a diameter of 1.6 mm. The length of the bar which will be welded is 40 mm.  
The CDW process was carried out using a special jig which was designed for this experiment and can be seen in Figure 1. Figure 1 shows a sketch and a photo of the CD Welder. With the special jig, welding parameters can be maintained in equal values or conditions. The inputted power, which in turn determines the heat input, was 120 Joule and the voltage was 75 Volt DC. The normal pressure is assumed equable by setting the load and tip distance before the drop, which were 4 kg and 5 mm, respectively.  
The independent variable of this research is a different surface preparation, which is described in the lower part of Figure 1 and called \(\alpha 0\), \(\alpha 1\), and \(\alpha 2\). In the figure, for the steel that is always on the left side, or also termed specimen \(\alpha 0\), both surfaces are flat, while for specimens \(\alpha 1\) and \(\alpha 2\), the steel and brass are sharpened, respectively. It should be noted that, for the sharpened surface at two tips the good joint was hard to be obtained and always produced misaligned components. Thus, there is no specimen with a sharpened tip for both metals. For all surface combinations, the steel, which has better weldability, was always gripped at upper chuck to obtain better results. Using all the described methods, welding parameters were considered to be constant, and the only altered parameter is the surface preparation, which is the only independent variable in this article.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Materials**} & \multicolumn{10}{c}{**Composition (weight \%)**} \\ \hline \multirow{3}{*}{
\begin{tabular}{c} **Low** \\ **Carb** \\ **Steel** \\ \end{tabular} } & Fe & C & Al & S & Cr & Si & Ni & P & Cu \\ \cline{2-11}  & Bal & 0.148 & 0.001 & 0.02 & 0.046 & 0.0015 & 0.092 & 0.008 & 0.103 \\ \cline{2-11}  & Mn & W & & & & & & & & \\ \cline{2-11}  & 0.555 & 0.04 & & & & & & & & \\ \hline \multirow{3}{*}{**Brass**} & Ag & Al & Bi & Cd & Co & Cr & Cu & Fe & Mg & Mn \\ \cline{2-11}  & \(<\)0.01 & 1.55 & 0.006 & \(<\)0.01 & \(<\)0.01 & 0.006 & 57.01 & 0.56 & 0.03 & 0.08 \\ \cline{2-11}  & Mo & Ni & Pb & Sb & Sn & V & Zn & & & \\ \cline{2-11}  & \(<\)0.01 & 0.35 & 2.22 & 0.04 & 0.98 & \(<\)0.01 & 36.51 & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Materials Composition.  
Figure 1: Capacitive discharge welding (CDW) process.  
After the joints were obtained, the next step was the SCC corrosion test, which is the dependent variable of this article. The focus for the dependent variable is the stress corrosion threshold, which describes the maximum stress, which is defined as the maximum allowed exerted stress where the SCC is assumed to not occur. Figure 2 shows the installation of the SCC, which was designated for this research. Figure 2 shows a sketch and a photo of the SCC apparatus. The dead load is attached at the end of the loading arm (right arm) and the applied load at the upper clamp can be counted by considering the length of each arm. The exerted tensile stress can be calculated by dividing the load by the original area of the base metal (\(\pi\)D\({}^{2}\)/4). The specimens, especially the interface, were dipped in the 1 Molar HNO3 solution. To obtain the SCC threshold, the load must be varied, and for each load the time to fail was recorded.  
The morphology of welded interfaces was analyzed using Hitachi SEM/EDS type FLEXSEM 100. The backscattered electron (BSE) was used to characterize the high magnification of cracks/voids of the welding joint. The composition mapping of the joint interface was analyzed using Energy Dispersive X-Ray Spectrometry (EDS).