PSI - Issue 36

Olexandr Ivanov et al. / Procedia Structural Integrity 36 (2022) 223–230 Olexandr Ivanov et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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1. Introduction Modern equipment and machines are operated under difficult conditions under high loads and temperatures in abrasive and corrosive environments, which leads to intensive wear of parts, and as a consequence – stopping of production processes. Using of reinforcing technologies allows to rationally combine of the properties of coating and base materials (Ropyak et al. (2020)), ensuring the accuracy of the drilling tool (Bazaluk et al. (2021)). Composite materials (Shihab et al. (2021)) are used for increasing the wear resistance of equipment parts. Reinforcement of the working surfaces of parts is carried out by friction treatment (Maksymiv et al. (2021)) and ultrasonic shock treatment (Vasyliev et al. (2016)). Chemical and thermal treatment has become widespread: ionic nitriding (Duryagina et al. (2011)), cementation (Yakym et al. (2020)) and obtaining eutectic coatings (Pashechko et al. (2017)). Functional single-layer oxide coatings, two-layer oxide coatings (Ropyak et al. (2021)) and multilayer oxide coatings (Ropyak et al. (2020)), nanocomposite coatings with non-metallic bond with content are used. diamonds (Buketov et al. (2018)) and oxides (Popadyuk et al. (2019)), as well as discontinuous coatings (Antonyuk et al. (2007)). A promising area is using of electric arc welded coatings. In the works (Melnick et al. (2020)), the phase composition of highly entropic alloys, was predicted. (Shihab et al. (2020)) described the formation of electric arc coatings based on high-manganese steel with titanium and niobium carbides, and (Prysyazhnyuk et al. (2020)) described Fe-Mo-B-C system. Hardfacing with powder electrodes is one of the most common used methods for restoring of parts of equipment or instruments and for increasing their durability. Due to high versality (Trembach et al. (2021)), Flux-cored arc welding (FCAW) is used in almost every of the technical branches, where restoring or increasing of durability of the equipment parts are required. This method not only can be described as simple and versality, it is also are characterized with high quality of the deposited layer, which allows to use FCAW for hardfacing of parts or instruments of responsible equipment. Most common used systems for production of powder electrodes are systems based on tungsten and based on chromium. Yet, tungsten-based materials are expensive and their usage are not always economically justified for restoring/increasing of durability of equipment parts of some branches. On the other hand, chromium-based materials are considered as an alternative to tungsten-based, they are characterized with high hardness and corrosion resistance. System based on Fe-Cr-C, with addition of a small amount of other alloying elements (Liu et al. (2012)), is one of the most used among the developers of modern serial electrodes. By some developers, such electrodes are presented as electrodes for hardfacing of surfaces that works under conditions of intense abrasion wear. However, such system is also characterized with some disadvantages, such as low crack resistance, low hardness of chromium carbides. Taking to account the above mentioned, researchers are experimenting with investigation of other systems (Marinenko et al. (2009)), that can provide higher durability under different kinds of wearing. One of such systems is Fe-Ti-C. Titanium carbides is hard, but due to fine size, they are not effective for increasing of durability, because while abrasion wear such carbides are subject to be remove with rest of material of hardfacing, which is less hard than abrasion particles. However, adding of other chemical elements (Pukas et al. (2020)), such as B, Cr, V, W and others is aimed on providing the structure of uniformly distributed hard particles in metal matrix and, as a result, increased mechanical properties and wear resistance of hardfaced layer. In addition to the chemical composition of system itself, such parameters as coefficient of filling of metal sheath with reaction mixture and welding parameters are important for providing high quality FCAW process (Trembach et al. (2021)). Current, as a part of welding parameters, determines the degree of melting of the base material and the intensity of transfer of the electrode material to the reaction zone. Usually, for FCAW method, 220-250 A current is used, as it can provide relatively fast and productive harfacing (Coronado et al. (2009)). Under such current, melting of base material, in the contact zone is intense, which provides intense mixing of it with electrode material, due to what the volume amount of deposited electrode material is reduced in the first hardfaced layer. As follows, there is a difference of properties in the deposited layers, which requires surfacing in several layers to ensure the required properties of hardfaced surface. However, for some equipment parts, especially for increasing of durability, there is a need to ensure high mechanical properties in the first deposited layer, as well as minimal temperature effects on the base material. The thermal cycle of welding processes is an important characteristic that determines the kinetics of the phase transformations and, accordingly, the degree of deviation of the phase composition from equilibrium. In addition to