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Документ Development of innovative method of steel surface hardening by a combined chemical-thermal treatment(Scientific Route, Estonia, 2016) Kostyk, KaterynaThe aim of the article is a hardening of the surface steel layers due to the combination treatment. Samples of steel 38Cr2MoAl were hardened by complex chemical and thermal treatment such as carburizing and subsequent boriding. It was established that surface double-layer hardening for steel 38Cr2MoAl with sequential saturation with atomic carbon (during carburizing) and atomic boron (during furnace boriding) at different temperatures allowed to form a boride layer with transition zone. The obtaining transition zone can improve operational properties of machine parts and tools by micro-friability reduction of diffusion layer. An optimal mode of complex chemical-thermal treatment (CTT) was obtained for the regime, which includes carburizing at 950 °C for 2 hours, boriding at 950 °C for 2 hours, which allows to get the best value for the surface hardness of 22 GPa with a maximum overall diffusion layer 1.4 mm. Due to the technology of combined treatment we can significantly reduce treatment time compared to traditional hardening means and significantly improve product performance properties due to the transition zone between the borides and the matrix of machine elements. The technology can be used in enterprises where there is any hardening furnace without additional installation or conversion of equipment.Документ Surface hardening of steel parts(Одеський національний політехнічний університет, 2017) Idan, Alaa Fadhil І; Akimov, O. V.; Kostyk, K. O.Development of new resource-saving and costeffective technologies of combined hardening of steel parts with a significant reduction of the process duration is an important and urgent task. Aim: The aim of the work is to create a technology for combined toughening of steel parts to provide high operational properties of the steel surface layer by intensifying the nitriding process through the laser pre-treatment of steel products. Materials and Methods: Materials for study are types of steels 40, 40Cr and 38Cr2MoAl. Laser treatment of steel was performed at the LATUS-31 installation. Nitriding carried out in the environment of fine nitrogen-containing substance with activators at a temperature of 530…560 ºC during 2…3 hours. The nitriding process was carried out in the closed atmosphere in the chamber furnace without application of the protective atmospheres. Influence of laser pre-treatment and final nitriding on structure, thickness, phase structure, microhardness of surface layers of steel samples has been investigated. Results: It is shown that preliminary hardening by laser increases surface hardness in 0.88…1.15 times after nitriding, depending on brand of steel and speed of a laser beam movement, in comparison with steel nitriding in similar conditions. The combined treatment promotes significant increase in the strengthened layer – up to 0.49 mm for 40 steel type, up to 0.55 mm for 40Cr steel type and up to 0.65 mm for 38Cr2MoAl steel type.Документ Development of a combined technology for hardening the surface layer of steel 38Cr2MoAl(Технологический центр, 2017) Idan, Alaa Fadhil І; Akimov, Oleg; Kostyk, KaterynaDevelopment of new combined strengthening technologies for treatment of steel surface layer is a topical issue. Influence of conditions of combined hardening treatment on variation of properties of the surface layer of 38Cr2MoAl steel was studied. Experimental data have shown that thickness of the hardened layer of 38Cr2MoAl steel, depending on the process conditions of combined treatment, varied in the range 0.18 to 0.69 mm with the surface hardness being 10.5-12.5 GPa. Mathematical models of the hardened layer thickness and surface hardness were obtained depending on variation of velocity of the laser beam travel and duration of nitriding of steel following the combined treatment. In their structure, the models are regression equations. These regularities have practical technological significance and ensure prediction of values of the hardened layer thickness and surface hardness. Nomograms of simultaneous influence of velocity of the laser beam travel and duration of nitriding on thickness of the hardened steel layer and surface hardness were constructed. Nomograms make it possible to determine concrete conditions of hardening processing, starting from specified thickness of the hardened layer or the surface hardness of 38Cr2MoAl steel, respectively and also to solve inverse problems. This method is suitable for hardening hard-to-reach part sectios and local contact areas.Документ Инновационная технология скоростного азотирования стали(НТУ "ХПИ", 2016) Идан, Алаа Фадил И; Акимов, Олег Викторович; Костик, Екатерина АлександровнаЦелью данной работы является разработка скоростной технологии упрочнения деталей для обеспечения высоких эксплуатационных свойств поверхностного слоя стали 38Х2МЮА. Интенсифицирован процесс азотирования за счет предварительной лазерной обработки поверхности стальных изделий. Изучено влияние предварительной лазерной обработки стали на изменение глубиныупрочненного слоя. Получены закономерности изменения толщины упрочненного слоя в зависимости от скорости передвижения лазерного луча для поверхностных слоев стали 38Х2МЮА обработанных только лазером и комбинированной технологией упрочнения. Изучено влияние предварительной лазерной обработки стали на изменения значений поверхностной твердости. Установлено, что увеличение скорости передвижения лазерного луча резко снижает поверхностную твердость стали.