# Advantages of Corrosion-Resistant Overlay Welding on Steel S355J2N
## 4 Results
### Electron Microscopic Examination  
In order to obtain a more detailed image of the specimen, we also took images with a scanning electron microscope with a greater depth of field.  
The scanning electron microscope creates images from secondary electrons, thus providing information about the chemical distribution as well. The EDX analyses were performed using a Bruker X-ray spectrometer (Bruker AXS Mikroanalysis GmbH, Berlin, Germany) -equipped Hitachi 3400N scanning electron microscope.  
The locations of the point analyses are marked with a green cross and a red arrow. Figure 15 shows the results of the first austenite point analysis (FH-WM1 austenite 1) of the first layer, while Figure 16 displays the results of the first delta ferrite point analysis (FH-WM1 delta ferrite 1) of the first layer.  
Point analyses were also performed in the base material, the welds deposited with filler materials, and the mixing zones, with two analyses conducted in each area. We were interested in the proportions of alloying elements in the different microstructural phases (austenite, delta ferrite). The images also show smaller carbides, inclusions, and pores, which were examined as well, but their number is so minimal that they do not play a significant role in the evaluation of the microstructure, and therefore, they are not included in the measurement results. The results are summarized in Table 3 for easier reference.  
Figure 14: Microscopic photos: (**a**) BM–S355J2N, showing corrosion on base metal; (**b**) WM1, 1 st layer microstructure: delta ferrite + austenite; (**c**) WM1-WM2, the edge of the 1 st layer and 2 nd layer; (**d**) WM2-WM3, the edge of the 2 nd layer and 3 rd layer; (**e**) WM3 microstructure at higher magnification.  
Figure 16: FH-WM1 delta ferrite 1 point analysis results.  
Figure 15: FH-WM1 austenite 1 point analysis results.  
In Figure 17, we contextualized the changes in Cr and Ni, which clearly form a directed pattern depending on which microstructural phase they are found in.  
The diagram essentially corresponds to the weld's resistance curve, which, despite fluctuations, shows uniform corrosion resistance well above the first resistance threshold. The curve clearly demonstrates the opposite directional changes in the amount of Cr and Ni alloying elements in the austenite matrix and delta ferrite net. The depicted trend indicates that the austenite matrix contains less chromium than the delta ferrite [29; 35], but  
Figure 17: Chromium and nickel content of the layers.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Cr** & **Ni** & **Mo** & **Mn** & **Fe** & **Si** \\  & **\%** & **\%** & **\%** & **\%** & **\%** & **\%** \\ \hline  
$-ferrite 1** & 23.17 & 7.19 & 4.55 & 1.84 & 62.74 & 0.52 \\ \hline
**WM3 \$-ferrite 2** & 22.75 & 7.52 & 4.84 & 1.58 & 62.74 & 0.56 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Chemical compositions of point examinations.  
the austenite is not significantly depleted, which confirms the minimum risk of chromium carbide precipitation. In none of the measurement points did the chromium content fall below the first resistance threshold (12%), ensuring passivity against corrosion.