## 1 Introduction
In addition, an improved method of multilayer plasma surfacing of heat-resistant steels in a nitrogen atmosphere is presented as preventing cracking and increasing surface metal hardness without subsequent heat treatment. The article [19] is based on the results of fabricating multilayer semi-finished products and laminates, shaping the structure and properties of homogeneous and heterogeneous materials using plasma surfacing with straight and reverse polarity currents. It is shown that reverse-polarity plasma surfacing provides good layer fusion with minimal heat input to the base material and filler. This reduces the thickness of the fusion zone and the mixing of metal in the layers. In addition, cathode cleaning reduces the likelihood of interlayer defects. The paper [20] presents the results of a study of the structure, phase formation, and properties of chromium-nickel alloys in plasma surfacing of high-alloy steel wire. In order to investigate the possibility of structure modification during argon arc deposition, an additional ultrasonic action was applied to the deposited material using a waveguide connected to the bottom surface of the sample. A comparison of the surface alloy structures obtained by laser deposition showed that arc welding of the alloy combined with ultrasonic action created an additional effect of increasing phase dispersion, which led to an increase in the strength of the alloy at high temperatures. In the study [21], a medium entropy CoCrFeMnNiW alloy coating on Q235 was produced using plasma spraying technology. The wear resistance of the prepared single-layer coating and the double-layer coating was investigated using a friction and abrasion tester. The microstructure and performance of the CoCrFeMnNiW coating were investigated using optical microscopy, a nano-hardness test, SEM, and a hardness tester. The results showed that the microstructure of the coating was composed of a melt zone, equiaxial dendrites near the fusion zone, coarse co-luminal and near-surface crystals in a specific direction between the melt zone, and near-surface fine equiaxial grains. What distinguishes this research from the existing literature is its comprehensive analysis of the specific impacts of variable plasma surfacing parameters on C45 steel, particularly focusing on weld geometry, the dilution factor, and microhardness. Unlike previous studies that may have addressed these factors individually or in different contexts,this research provides a holistic examination, integrating these aspects to offer a clearer understanding of their interdependencies. The concrete contribution of this study lies in its detailed investigation of how specific changes in plasma surfacing parameters can be optimized to achieve precise weld characteristics, thereby enhancing weld quality and performance. This work also provides practical guidelines for industry professionals aiming to improve plasma surfacing outcomes for C45 steel, bridging the gap between theoretical research and practical application. In this study, the aim was to investigate the effects of varying plasma surfacing parameters such as arc intensity, arc voltage, deposition speed, feed rate and torch distance from the work surface on the surfacing geometry, the dilution coefficient, and microhardness. The parent material was C45 unalloyed steel, the filler material was 45554S stainless steel wire, and the surfacing was carried out under protective argon gas shielding.