## 1 Introduction
From the perspective of hardfacing through welding, the greatest disadvantage of these steels is that when subjected to the typical thermal cycle of a coating process (temperatures of 300-1000 \({}^{\circ}\)C), they readily and quickly form a variety of fragile phases such as sigma (6), chi (\(\varkappa\)), and alpha-prime (\(\alpha\)) [6; 7; 8; 9]. This is practically unavoidable because during hard loading through welding, a thin portion of the surface of the piece melts, and even if the majority of the material remains below 300 \({}^{\circ}\)C, there is always an intermediate microzone (near the deposited layer-substrate interface) that will experience temperatures in the embrittlement range, even if only for a short period. To avoid precipitation phenomena, it is necessary to maintain the temperature between two successive passes at approximately 150-200 \({}^{\circ}\)C. This ensures that the time spent in the embrittlement zone is minimized. In recent years, numerous research efforts have been undertaken to modify the microstructure of the surface layers of these steels in order to increase hardness and improve resistance to wear through friction and cavitation erosion. Among these, examples include laser beam welding, TIG welding, thermal spraying, and plasma nitriding. Thus, [PERSON] et al. investigated the effect of TIG (GTAW) and CO\({}_{2}\) laser beam welding (LBW) processes on the dimensions, microstructure, mechanical properties, and corrosion resistance of welded joints of duplex stainless steel, grade 2205 [13]. The results showed that LBW, compared to GTAW, provides better corrosion resistance (corrosion rate is 0.05334 mm/year for LBW and 0.2456 mm/year for GTAW). The explanation for these differences is based on the smaller dimensions of the welded joint and the heat-affected zone in the case of LBW welding. [PERSON], [PERSON]. [14] demonstrated that by preplacing Ti powders on the surface of steel and subsequently remelting with TIG welding of the marginal layer, hardness increases to approximately 2000 HV due to the formation of TiN compounds, thus justifying the reduction in wear rate. [PERSON], [PERSON]. [15] have shown that by TIG melting of the surface or by applying thermochemical gas nitriding treatment, significant surface hardening of duplex stainless steels is achieved, which promotes improvement in wear and corrosion resistance. [PERSON] et al. [16] and [PERSON] et al. [17] established that gas nitriding at temperatures of 400 \({}^{\circ}\)C-500 \({}^{\circ}\)C for 6 h in plasma leads to an increase in the hardness of duplex stainless steels to values exceeding 650 HV. The formation of expanded austenite was observed in the temperature range of 400 \({}^{\circ}\)C-500 \({}^{\circ}\)C, and chromium nitrides appearing at 500 \({}^{\circ}\)C decreases corrosion resistance. The expansion of the potential applications of duplex stainless steels to parts operating under conditions of frictional wear and cavitation erosion has led the authors of this study to characterize the microstructure of coatings made of Fe-C-Mn-Cr-Ni alloys of the \"Citomanganese\" type deposited by arc welding with pulsed current. These alloys were developed based on Hadfield steels and are delivered in the form of powders, tubular wires, and coated electrodes. Because they have a high capacity for work hardening, they are recommended for use in hardfacing through welding of valves, shafts, and other components in industries such as automotive, aerospace, petrochemical, and metallurgical, which are subjected to intense wear stresses during operation [18; 19; 20; 21; 22; 23; 24]. Based on our knowledge, there are currently no available reports regarding the microstructure and hardness of the coating-substrate system under hardfacing of duplex stainless steels with austenitic manganese alloys using the manual shielded metal arc welding technique with pulsed current.