## 3 Results and Discussion
### Evaluation of the Corroded Surface  
The shape of the corroded area of the two different sample types was not the same (Figure 7). The corroded area was heterogeneous with cracks on the wrought sheet area (Figure 7a,b). The heterogeneity of the corroded surface validates the localised corrosion indicated in AEN analyses. This is the typical corrosion for 316L stainless steel. The chloride ions can cause local dissolution of the passive film, producing cracks [25]. Corroded LPBF samples (Figure 7c,d) showed pitting localised in the voids and molten front. The passive film is weaker in the voids, encouraging the formation of pitting [25]. The corroded area of the wrought sheet samples was two times larger than that for the LPBF samples, further indicating the LPBF material's higher corrosion resistance.  
The distribution of the chemical elements in the corroded area was different according to the sample (Figure 8). The corroded area on the wrought sheet samples (Figure 8a) showed a higher concentration of the carbon and oxygen while iron, chromium, and nickel had lower concentrations on the area. This indicates localised damages of the passive film. For the LPBF samples, the concentration of the elements was found to be homogeneous, meaning that the passive film was less damaged. The good resistance of the LPBF sample's passive film is due to the large grain size that mitigates the cathodic effect of the grain  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Time** & **R\({}_{a}\)** & **CPE\({}_{pass}\)** & **R\({}_{pass}\)** & **CPE\({}_{bared}\)** & **R\({}_{bared}\)** & **R\({}_{bared}\)** & **d** & **\(\chi^{2}\)** \\  & **(h)** & **(\(\Omega\)cm\({}^{-2}\))** & **(\(\mu\)S\({}^{n}\)cm\({}^{-2}\))** & **(\(\mu\)S\({}^{n}\)cm\({}^{-2}\))** & **(\(\mu\)S\({}^{n}\)cm\({}^{-2}\))** & **(\(\Omega\)cm\({}^{-2}\))** & **(\(\Omega\)cm\({}^{-2}\))** & **(\(\Omega\)cm\({}^{-4}\))** \\ \hline \multirow{6}{*}{Wrought} & 2 & 2.010 & 46.680 & 0.92 & 0.225 \(\times\) 10\({}^{6}\) & 9.510 & 0.90 & 3531 \(\times\) 10\({}^{3}\) & 0.339 & 6.080 \\ \cline{2-10}  & 24 & 3.220 & 22.000 & 0.92 & 0.147 \(\times\) 10\({}^{6}\) & 4.420 & 0.66 & 1750 \(\times\) 10\({}^{3}\) & 0.718 & 4.310 \\ \cline{2-10}  & 48 & 3.070 & 20.500 & 0.93 & 0.065 \(\times\) 10\({}^{6}\) & 3.874 & 0.58 & 2370 \(\times\) 10\({}^{3}\) & 0.771 & 2.740 \\ \cline{2-10}  & 72 & 3.490 & 19.700 & 0.93 & 0.077 \(\times\) 10\({}^{6}\) & 3.690 & 0.51 & 3030 \(\times\) 10\({}^{3}\) & 0.802 & 4.190 \\ \cline{2-10}  & 96 & 2.880 & 19.200 & 0.92 & 0.064 \(\times\) 10\({}^{6}\) & 2.500 & 0.61 & 2500 \(\times\) 10\({}^{3}\) & 0.823 & 2.760 \\ \hline \multirow{6}{*}{LPBF} & 2 & 3.890 & 21.453 & 0.92 & 0.052 \(\times\) 10\({}^{6}\) & 2.778 & 0.93 & 32 \(\times\) 10\({}^{3}\) & 0.737 & 3.528 \\ \cline{2-10}  & 24 & 2.652 & 314.250 & 0.57 & 0.867 \(\times\) 10\({}^{6}\) & 18.250 & 0.95 & 879 \(\times\) 10\({}^{3}\) & 0.050 & 2.879 \\ \cline{1-1} \cline{2-10}  & 48 & 3.554 & 15.508 & 0.96 & 4.483 \(\times\) 10\({}^{6}\) & 87.697 & 0.87 & 37 \(\times\) 10\({}^{3}\) & 1.020 & 5.829 \\ \cline{1-1} \cline{2-10}  & 72 & 3.616 & 17.185 & 0.97 & 4.980 \(\times\) 10\({}^{6}\) & 464.900 & 0.70 & 8 \(\times\) 10\({}^{3}\) & 0.920 & 8.608 \\ \cline{1-1} \cline{2-10}  & 96 & 3.098 & 18.050 & 0.94 & 4.997 \(\times\) 10\({}^{6}\) & 300.793 & 0.76 & 235 \(\times\) 10\({}^{3}\) & 0.876 & 4.829 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Corrosion mechanism evolution features of the samples in 0.6 M from EIS.  
Figure 7: Corroded areas of the wrought sheet (**a,b**) and LPBF sample (**c,d**).  
boundary. The cathodic effect of the grain boundary encourages the corrosion of the 316L stainless steel. The high concentration of the molybdenum contributes to the cathodic effect at the grain boundary [1,2,17,18].