## 2 Materials and Methods
### Specimen Preparation and Analysis  
An initial investigation was conducted to compare CMT+P with CMT-conventional, which confirmed the suitability of CMT+P for the deposition of Cu1897. After successful trials, wire feed speed (WFS) and torch speed (TS) of 9000 mm/min and 300 mm/min were selected for material deposition, respectively. Furthermore, a gas flow rate (GFR) of 14 L/min was utilized, which was identified as optimal through the initial study, as a high gas flow rate can reduce the bead's penetration [18]. An interlayer temperature of 100 \({}^{\circ}\)C was kept for depositing the second and third layers of Cu1897. The reason for depositing the second and third layers was to study the effects of PC and ALC on porosity in WAM of Cu1897, as in the first layer, very minute porosity was observed due to the strong intermixing of copper and steel.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & \multicolumn{6}{c}{**Chemical Composition of Cu1897 (\%)**} \\ \hline
**Cu** & **Ag** & **Mn** & **Sn** & **Ni** & **Zn** & **Fe** & **P** & **Pb** & **Al** \\ \hline Rem. & 0.86 & 0.065 & 0.003 & 0.001 & 0.006 & 0.002 & 0.014 & 0.001 & 0.001 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chemical composition of Cu1897.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & **Chemical Composition of S235 JR (\%)** & & & \\ \hline
**Fe** & **C** & **Mn** & **P** & **S** & **N** & **Cu** \\ \hline Rem. & 0.190 & 1.5 & 0.045 & 0.045 & 0.014 & 0.55 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Chemical composition of S235 JR (\%).  
Three distinct values were initially used to investigate the effects of PC on bead penetration, which are \(-5\), \(0\) and \(+5\). Three layers were deposited on top of each other for each value of PC, and the resulting samples are shown in Figure 2.  
The samples were cut through a wire--electric discharge machine at three sections, as shown in Figure 2, and mounted using PolyFast powder as mounting material. For the specimens to achieve a mirror-like surface finish, their surfaces were ground with an automatic grinding and polishing machine using a series of abrasive papers of SiC (silicon carbide) from 400 to 2000 grit and eventually with diamond suspensions. The specimen at PC \(=-5\) after grinding and polishing is shown in Figure 3.  
These specimens were then observed under an optical microscope, ZEISS Axio Imager.M2m (from Carl Zeiss AG, a company based in Jena, Germany), to study the effects of PC on bead penetration. The optimal PC was then selected and kept constant while the ALC was varied to investigate its effects on bead penetration and porosity. Arc length is influenced by ALC, and variations in ALC can lead to various changes in bead characteristics. In the Fronius CMT welding machine (model--TPS 5000), the ALC ranges from \(-30\%\) to \(+30\%\). Five different values of ALC were used for investigation in this study, which are \(-30\), \(-15\), \(0\), \(+15\), and \(+30\) and the specimens deposited using these parameters are presented in Figure 4.  
Figure 3: Sample after polishing at PC \(=-5\).  
Figure 2: Cu1897 samples prepared by varying PC at constant ALC \(=0\%\).  
To study the effects of ALC on bead penetration and porosity, samples were cut at three sections as shown in Figure 4 and prepared in a similar way to that in the PC study. The study of bead penetration and porosity was performed in ImageJ, version 1.54j (an open-source software for image processing and analysis).