## 2 Materials, Experimental Procedure  
The base material used as a substrate was duplex stainless steel 2205, symbolized as X2 CrNiMoN22-5-3 according to the European standard EN 10088 and UNS S31803 according to ASTM A276. Before the hardfacing process, it underwent a solution annealing heat treatment at a temperature of 1060 \({}^{\circ}\)C followed by rapid cooling in water. Table 1 presents the nominal chemical composition of this steel (determined by optical emission spectrometry using Thermo Arl QuantoDesk equipment from Thermo Fisher Scientific, Burladingen, Germany), and Table 2 shows the obtained values for the main mechanical characteristics at room temperature (determined using the equipment Zwick/Roell Z005, Ulm, Germany). The selected filler material was the CITOMANGAN electrode with a basic coating of austenitic manganese steel, symbolized DIN 8555: -E 7--UM--200 KP, and EN 14700: E Fe 9, respectively, which is recommended for deposition of wear-resistant layers under conditions of strong impacts and shocks. The guaranteed chemical composition of the deposited metal is as follows: 0.60% C, 15% Mn, 4.5% Cr, 4.8% Ni, and balance Fe. Using a universal welding source MAGIC WAVE 300, from Fronius company, which allows, as an option, manual welding with pulsed current electrodes (Figure 1), depositions of 1, 2, or 3 layers of austenitic manganese steel (electrode) were made on the considered steel substrates. The novelty lies in the fact that in the welding torch head, in its grip, instead of the non-fusible tungsten electrode, the selected coated electrode for hardfacing was fixed. Welding by melting with the electric arc in pulsed current differs from conventional welding in that the welding current varies over time between a maximum value called the pulse current and a minimum value called the base current, at a certain frequency (Figure 1). By adjusting the level of specific parameters: I\({}_{\text{p}}\), I\({}_{\text{b}}\), t\({}_{\text{p}}\), t\({}_{\text{b}}\), and f, it is possible to precisely dose the energy introduced into the components of the coating-substrate system. Melting of the material and formation of the weld bath occurs during a pulse, while stable burning of the electric arc is maintained during the base time, resulting in cooling with partial solidification of the molten bath. At the same average welding current, the penetration of the weld beam is greater than in conventional welding, and the linear energy is lower. Through preliminary trials and based on data obtained from literature, the following conditions for carrying out the welding process in pulsed current were established:  
- Basic coated electrode: CITOMANGAN;  
- Electrode diameter: 3.25 mm;  
- Polarity: DC+;  
- Pulse current, I\({}_{\text{p}}\): 180 A; \begin{table}
\begin{tabular}{c c} \hline \hline Carbon (C) & 0.021\% \\ Silicon (Si) & 0.79\% \\ Manganese (Mn) & 0.82\% \\ Phosphorous (P) & 0.019\% \\ Sulfur (S) & 0.012\% \\ Chromium (Cr) & 22.34\% \\ Nickel (Ni) & 5.61\% \\ Nitrogen (N) & 0.14\% \\ Molybdenum (Mo) & 3.1\% \\ Iron (Fe) & Balance \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The chemical composition of the analyzed steel substrate. Figure 1: The parameters of the pulsed current welding process. - Base current, \(\mathrm{I_{b}}\): 90 A (50% of \(\mathrm{I_{p}}\));
- Average current, \(\mathrm{I_{m}}\): 135 A;
- Arc voltage, U: 22 V;
- Pulse frequency, \(\mathrm{f=1/t_{c}=5\ Hz}\);
- Cycle time, \(\mathrm{t_{c}=1/f=1/5=0.2\ s}\);
- Pulse time, \(\mathrm{t_{p}=0.5\ t_{c}=0.1\ s}\);
- Base time, \(\mathrm{t_{b}=0.5\ t_{c}=0.1\ s}\) (\(\mathrm{t_{p}=t_{b}}\));
- Arc length, \(\mathrm{I_{a}=3.0\ mm}\);
- Welding rate, \(\mathrm{v=27\text{--}28\ cm/min}\). Before welding hardfacing, the substrate surface was grinded with 120 gr SiC paper and cleaned with acetone. After each deposited layer, the surface was cleaned using a wire brush.