PSI - Issue 59

Olexandr Ivanov et al. / Procedia Structural Integrity 59 (2024) 622–628 Olexandr Ivanov et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Keywords: borides; carbides; microstructure; hardndess; wear resistance

1. Introduction Despite the economic and political factors tungsten-based materials are still widely used as main strengthening material in different industries: drilling and mining equipment, surfaces of details and elements of construction that work under increased working loads, working surfaces of the tillage equipment, etc. Using more economically effective materials with favorable mechanical properties is still perspective, open, and desirable aim for researchers with different directions of research. Different scientists that are working with developing and investigating new strengthening materials search system with high mechanical properties and with structure that provides high wear resistance working in different conditions. While mechanical parameters of phases and inclusions in structure is important, distribution of phases and their geometrical parameters are also important for wear resistance. Researches that are done can be roughly divided by the researching materials itself, methods of obtaining the material, methods of observation, laboratory and experimental approbation. Methods of obtaining includes sintering (Ishii et al. (2023)), flux-cored arc welding (FCAW) (Kumar and Vijayakumar (2023), Xu et al. (2022)) and many other that differs with practical features and prices. Hardfacing with FCAW is described as one of the most universal, practical and economically effective for strengthening of details. Most serial production hardfacing electrodes are based on the Fe-Cr-C system with addition of some other elements, while experiments are made with systems based on Fe-Ti C (Sejc et al. (2022)), Fe-Ti-B-C (Trembach (2023)), Fe-Ti-Mo-B-C (Bembenek et al. (2022)) and others, as well as changing the main Fe element with different elements from iron group, such as Co (Hsieh et al. (2013)), Ni and Mn (Prysyazhnyuk and Tommaso (2023)). Research often includes not only experimental approbation but also modeling of different aspects of material, its structure, formation features and properties. Such modeling includes mathematical and thermodynamic modeling, study of results of working, failures, heat propagation in materials, etc. Modeling could be based on experimental, theoretical or combination of this data. While modeling based on strictly theoretical data can, in some way, predict the phase formation of the material it is also should be taken into account that technological parameters are highly important for their practical using in real working conditions. For practical using of materials technological parameters are highly important as it can affect mechanical properties and wear resistance in long term periods, as defects in material can lead to the material/detail failure while working. Despite the serial using of electrodes based on Fe-Cr-C system, such system, due to formation of coarse M7C3 carbides with low crack resistance, characterized with defects while obtaining (Buchanan et al. (2007)) and wearing (Sabet et al. (2011)). For material with including of Mo in composition there are experimental data (Zhang et al. (2018), Wang et al. (2008)) of defects presence in the structure, while other work (Yang et al. (2017)), with different method of obtaining, shows presence of molybdenum in high amount (up to 34 at. %) without mention of defects presence in structure. According to literature review hardfacing systems with increased amount of Mo seems like promising for investigating with further experimental tests as potential alternative for tungsten-based materials in term of material for restoring and increasing the durability. In this research, hardfacings obtained with FCAW with flux-cored electrodes based on Fe-Ti-Mo-B-C system with different ratio between Ti and Mo are tested. Testing includes hardness measurement and wear resistance testing in condition of working with fixed, non-fixed abrasive and impact-abrasive load. Also scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis for obtained hardfacings are made. 2. Methods and materials Electrod es producing. For researching the mixture of prepared dried fine grained (~5 μm) powders of initial components (Ti, Mo, B, C) were placed into 08kp steel (DSTU 7809:2015) cold rolled shell (DSTU EN 10139:2018) by rolling. Width and height of the electrode is 8  2,5 mm, 420 mm length. Proportions between metal shell and powder filler, and between components in filler was chosen in order to ensure the same ratio between Fe, C and B in each sample with different ratio between main strengthening components Mo and Ti. Chemical composition of 08 kp steel presented in Table 1 as well as chemical composition of produced electrodes presented in Table 2.