The influence of charge materials of flux-cored wires on their mechanical characteristics, chemical microheterogeneity and corrosion resistance in an aqueous solution of 3% NaCl was established. It is shown that, in contrast to coatings made of solid wires, coatings sprayed using flux-cored wires (PO) have a high chemical heterogeneity. This is due to the fact that the droplets that disperse from the PD melt and form a coating have different chemical compositions. This is caused by incomplete fusion of the charge and steel shell at the ends of the PD during electric arc spraying of coatings. To reduce the chemical micro-heterogeneity, it is proposed to add powders of ferroalloys FeSi, FeMn and self-flux PG-10H-01 to the charge of powder wire containing chromium, boron, carbon-containing components (Cr, FH, PG-100, B4C, FCB) between the components of the charge, homogenize the melt of PD and, as a consequence, reduce the microheterogeneity of the coatings. The presence of chromium, ferrochrome, ferro-silicon and ferromanganese in the charge of PD 90Х17РГС and PD 75Х19Р3ГС2 determines the minimum chemical microheterogeneity of coatings from these wires and, as a result, ensures their high corrosion resistance, which is close to corrosion steel18. To increase the completeness of fusion of the components of the PD charge between itself and its steel shell, it is proposed to add to the PD charge powders of ferroalloys Fe-Mn, Fe-Si, which have a low melting point, able to interact with refractory components of the charge to form low-temperature eutectics. The addition of ferro-silicon, ferromanganese and self-flux alloy PN-10H-01 powders based on ferrochrobor and ferrochrome provided high hardness of electric arc coatings, low heterogeneity in terms of chromium content in coating lamellae and, as a consequence, high corrosion resistance.

The influence of the diameter of the electrode flux-cored wires on the mechanical characteristics of the electric arc coatings is carried out in the work. Electric arc coatings were obtained on the original equipment, developed and manufactured at the Institute of Physics and Mechanics. GV Karpenko NAS of Ukraine. For spraying, model flux-cored wires of basic doping systems Fe – Cr – C and Fe – Cr – B with a diameter of 1.6 and 2.4 mm were used. The influence of the diameter of flux - cored wires on the structure, electric arc coatings from model flux - cored wires of different diameters is investigated. The dependence of porosity, microhardness, adhesion to the steel base, abrasive wear resistance of electric arc coatings sprayed from flux-cored wires with different amounts of charge on the thickness of the lamellae in the coating structure has been established. The influence of the thickness of the lamellae in the structure of coatings sprayed from flux-cored wires with different amounts of charge (depending on their diameter 1.6 and 2.4 mm) on their abrasive wear resistance was determined. It was found that the thickness of the lamellae in the coatings of all analyzed alloying systems increased with increasing volume of molten metal at the ends of flux-cored wires with the corresponding formation of droplets of larger diameter during its dispersion by air jet. shell charge and high arc current. It is shown that the amount of oxide phase in the structure of coatings doubles with increasing spray distance of flux-cored wires from 80 to 120 mm. More oxide phase (40… 100%) was found in coatings formed of flux-cored wires with a diameter of 2.4 mm with a higher filling factor of its shell charge compared to coatings formed of flux-cored wires with a diameter of 1.6 mm with lower filling. This is due to the larger volume of the charge in the powder wires of larger diameter, the cavities between the powders in which are filled with air, which intensively oxidizes the melt droplets inside the powder wires and at their ends during spraying. It is established that the porosity and microhardness of coatings from the developed flux-cored wires increase with the increase of the thickness of the lamellae in their structure and, accordingly, the diameter of the flux-cored wires. The increase in micro hardness is due to less evaporation and burnout of alloying elements from the droplets forming the coating, and the increase in porosity is caused by intensive spraying of droplets when hitting the sprayed surface, which contributes to micro cavities between the lamellae of the coating. It was found that with increasing the thickness of the lamellae in the structure of coatings of flux-cored wires 250H21VFGS and flux-cored wires 50HN2R5GS their adhesion to the steel base decreased slightly due to the occurrence of tensile stresses in coatings, which cause micro cracks or cracks. At the same time, the adhesion of 50X6MG2C flux-cored wire coatings to steel increased due to the higher carbon content of large lamellae and favorable conditions for the formation of high-carbon martensite, which has the lowest coefficient of thermal expansion and causes the lowest residual tensile stresses. It was found that the abrasive and gas-abrasive wear resistance of coatings from flux-cored wires 250Х21ВФГС decreased, and from flux-cored wires 50ХН2Р5ГС increased due to the increase in the thickness of the lamellae in their structure using a larger diameter.

Проаналізовано злами зразків після випробувань на ударну в’язкість, статичну тациклічну тріщиностійкість тривало експлуатованої (a2·105год ) теплостійкої сталі15Х1М1Ф. Фрактографічним аналізом зламів виявлено відмінності між станом металу, щопід час експлуатації переніс різну кількість зупинок блоків (501 та 576). А саме в металі збільшою кількістю зупинок частка міжзеренних фрагментів на фоні типового крізьзеренногорельєфу в зоні спонтанного руйнування зразків випробуваних на ударну в’язкість та статичнутріщиностійкість була високою, що пов’язано з його інтенсивнішою деградацією. Крім того, після випробувань на удар частка міжзеренних фасеток була більшою ніж за випроб настатичну тріщиностійкість, що пов’язано з більшим відхиленням тріщини (навіть надекілька зерен) від магістрального напряму її поширення. Тоді як при статичнихвипробуваннях руйнування відбувалося лише по тих ослаблених деградацією меж зерен, якітраплялися на шляху фронту магістральної тріщини. При циклічних випробуваннях наприпороговій ділянці росту тріщини на зламах експлуатованої сталі на фоні класичногокрізьзеренного втомного руйнування, виявили фрагменти міжзеренного руйнування, якіпов’язали з межами зерен пошкодженими внаслідок повзучості, які утворилися під частривалої експлуатації. Отримані результати дають підстави рекомендувати площуміжзеренного рельєфу, що припадає на одиницю площі зламів зразків з експлуатованоїтеплотривкої сталі, для кількісного оцінювання її структурно-механічного стану