# Development of an Alternative Alloying Concept for Additive Manufacturing Using PVD Coating
## 3 Results
### Comparison of Alloying Concepts  
As a comparison of the alloy concepts, the base wire DIN EN ISO 14341-A G 50 7 M21 4 Mo examined here is modified in its chemical composition so that it corresponds to a Mn4 Ni2 CrMo. The Mn4 Ni2 CrMo was produced by secondary metallurgy. These two filler metals are compared in their microstructural morphologies and mechanical properties. A welded composite is created for this purpose, shown in Figure 7.  
Figure 6: Average arc temperature over the ionisation potential of the elements [30]. As a basis, the chemical compositions are first considered, which, according to the manufacturer's specifications, should be present in the Mn\({}_{4}\)Ni\({}_{2}\)CrMo, be what the standard prescribes and be what is actually present in the alloy according to optical emission spectroscopy (OES). For comparison, the chemical composition of the alternative alloy concept is determined and listed in Table 3.  
In the reference structure in Figure 7, on the left, a clearly ferritic/matrensitic structure can be recognised. The ferrite is partly polygonal and an acicular ferrite. For comparison, the rebuilt modified 4 Mo is shown on the right in Figure 8. The same ocular magnification is selected. The difference in the exposure ratios is not to be considered in the observation, as this has no relevance. The microstructure of the modified 4 Mo has the same ferritic/matrensitic microstructure as the microstructure of the reference. Here also, ferrite is present both as grain boundary ferrite and as acicular ferrite. From a purely microstructural point of view, no difference can be detected between the reference and the alternatively alloyed filler metal. \begin{table}
\begin{tabular}{c c c c c} \hline  & \begin{tabular}{c} **Manufacturer** \\ **Specification**[33] \\ \end{tabular} & \begin{tabular}{c} **DIN EN ISO** \\ **16834** \\ \end{tabular} & \
\begin{tabular}{c} **Mn\({}_{4}\)Ni\({}_{2}\)CrMo** \\ **OES** \\ \end{tabular} &
\begin{tabular}{c} **Alternative** \\ **Alloy OES** \\ \end{tabular} \\ \hline C & 0.09 & 0.12 & 0.118 & 0.130 \\ \hline Si & 0.8 & 0.60–0.90 & 0.454 & 0.655 \\ \hline Mn & 1.8 & 1.60–2.10 & 1.190 & 1.60 \\ \hline Cr & 0.3 & 0.20–0.45 & 0.443 & 0.540 \\ \hline Mo & 0.55 & 0.45–0.70 & 0.426 & 0.420 \\ \hline Nb & - & - & 0.009 & - \\ \hline Ni & 2.25 & 1.8–2.3 & 1.619 & 1.67 \\ \hline Ti & - & - & 0.013 & 0.002 \\ \hline \end{tabular}
\end{table} 
Table 3: Chemical composition. Figure 7: Welded composite. Beyond the microstructure, the mechanical properties should also be comparable. As proven several times in preliminary work and in the course of the project, a direct conclusion can be drawn from the microstructural properties to the mechanical properties. The interpass temperature maintained in this work was kept constant at 150 \({}^{\circ}\)C for all welding tests. Furthermore, it must be taken into account that the chemical composition varies in relation to the standard, the manufacturer's specifications and the composition determined via optical emission spectroscopy. In two different investigations, significant differences in the yield strength and tensile strength of the weld metal were also determined. In none of the tests was the yield strength according to the manufacturer's specifications achieved, and in only one was the tensile strength achieved. When comparing the strength values with the alternatively alloyed Mn\({}_{4}\)Ni\({}_{2}\)CrMo, it can be seen that the yield strength is comparable to the rest of the tests. The tensile strength is slightly below the specified values. However, as already described, this can also be attributed to the difference in the interpass temperature and the variance in the chemical composition. Due to the high scatter of the results, the alternative alloy concept is considered to have normal variance and to be comparable.