## 2 Estimation of the Welding Parameters
### Size of the Nugget Areas  
There are two ways to calculate the missing welding parameters, the first is to estimate them according to the standard, and the second is to calculate the welding parameters from the welding report. Two procedures were used for welding the specimen, gas tungsten arc welding (GTAW) and SMAW. Based on reference [22], the following equations can be used to calculate the voltage. For GTAW with currents \(I\) up to 600 A, the voltage \(U\) is  
\[U=13+0.012I, \tag{1}\] \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Material** & **C\%** & **Si\%** & **Mn\%** & **P\%** & **S\%** & **Cr\%** & **Ni\%** & **Mo\%** & **Cu\%** & **N\%** & **Nb\%** \\ \hline
1.4550 steel & \textless{}0.08 & \textless{}1.00 & \textless{}2.00 & \textless{}0.045 & \textless{}0.03 & 17.00–19.00 & 9.00–12.00 & - & - & - & 1.00 \\ ESA OK & \textless{}0.030 & \textless{}0.50–1.00 & \textless{}0.50–1.20 & \textless{}0.025 & \textless{}0.020 & 18.5–20.5 & 9.0–11.0 & \textless{}0.5 & \textless{}0.5 & \textless{}0.15 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical composition. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Material** & **E (GPa)** & **\(\sigma_{y}\) (MPa)** & **\(c\) (J/kg\({}^{\circ}\)C)** & **\(\alpha\) (10\({}^{-5}\)/c)** & **\(\lambda\) (W/m\({}^{\circ}\)C)** \\ \hline
1.4550 steel & 195.62 & 17.88 & 204.69 & 449.48 & 14.46 \\ ESAB & 199.62 & 17.25 & 221.03 & 450.29 & 14.89 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Thermo-mechanical properties at 20 \({}^{\circ}\)C. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Number of Layers** & **Welding Process** & **Welding Position** & **Filler Material** & **Electrode Diameter (mm)** & **Current Type and Polarity** & **Current (A)** & **Electrode Run-Out Length (mm)** & **Burn-Off Time (s)** & **Electrode Inclination (*)** \\ \hline
1 & 141 & PA * & EAS 2-IG & 2.4 & DC negative & 120 & 40–60 & 60 & 60–80 \\
2 & 111 & PA & ESA OK & 4.0 & DC positive & 140 & 130 & 60 & 60–80 \\
3–9 & 111 & PA & ESA OK & 5.0 & DC positive & 180 & 160 & 65 & 60–80 \\
10–12 & 111 & PA & ESA OK & 4.0 & DC positive & 150 & 125 & 60 & 60–80 \\
13 & 111 & PA & ESA OK & 4.0 & DC positive & 150 & 150 & 60 & 80 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The welding report. It should also be noted that the welding speed must be less than \(v=4\) mm/s and the process efficiency \(\eta=0.6\). The SMAW voltage is calculated using the following equation:  
\[U=20+0.04. \tag{2}\]  
Here the maximum welding speed is the same as in the case of GTAW, but the efficiency is higher, \(\eta=0.8\). From this, the welding heat input can be calculated using the following equation:  
\[P=\eta UI/v. \tag{3}\]  
The next step is calculating the nugget areas, which can be determined from the rate of the welded volume and the electrode run-out length. The volume can be calculated from the electrode's length and diameter. Two types were used for the studied weld, the EAS 2-IG and the ESAB OK 61.30. The length of the ESAB OK 61.30 electrode is 350 mm, but it is safe to estimate that 50 mm of that length is not consumed in the welding process. From the data provided, the estimated values of stress, volume, and void area were determined and are shown in Table 4.  
The second calculation version of the welding parameters is based on the welding report. The welding speed can be calculated using the given electrode run-out length and burn-off time; the welding heat input can be determined as well. The relationship between the cross-sectional area of the weld filler metal introduced per pass and the electrical heat input per unit length was measured in reference [23] for SMAW welding of austenitic steels. Based on the data in [23], the weld heat input and the area of the nuggets can be estimated for different current values. These values are summarised in Table 5. It should be noted that the equation given in reference [23] does not consider the welding efficiency; therefore, the last column of the table shows the actual nugget areas.