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Registration Number

0219U004816, 0118U006911 , R & D reports

Title

Increasing the complex of mechanical properties of structural and tool steels due to optimization of the chemical composition and methods of thermal and chemical-thermal treatments.

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Head

Cheiliakh Alexandr Petrovich, Доктор технічних наук

Registration Date

11-11-2019

Organization

State Higher Educational Institution "Pryazovskyi State Technical University"

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The object of research - semi-finished products and finished products from structural and instrumental steels, which were subjected to different methods of volume and surface hardening. The purpose of the work is to improve the quality of metal products due to doping, surface and volume treatments. Research methods - analytical calculations, dilatometric method, macro, microscopic and fractographic analyzes, X-ray phase analysis, tests of mechanical and operational properties The first section shows that there are important rational temperature and time parameters during the quenching from the intercritical temperature range and the next tempering. Environmentally friendly methods of intermittent and isothermal quenching allow for a good combination of mechanical properties. This reduces energy costs compared to typical heat treatment, in some cases, using of expensive and fire-hazardous oils and non-organic melting salts (alkalis) is eliminated. In the second section, the influence of plasma modification on the properties of high-carbon steels and alloys is studied: the hypereuctoid steel (1,2 % C), graphite steel of 1,5 % С doped with chromium, nickel and molybdenum, gray cast iron and ( в=180 MPa and в=400 MPa), high-strength cast iron ( в=600 MPa). As a result of plasma surface modification the hardness for hypereuctoid steels, gray and high-strength iron increases in 3 times, and for white iron - in 2 times is shown. In this case, there is no significant embrittlement, which is associated with qualitative changes in the micromechanism of destruction of the metal of the modified zone. As a predominant micromanagement of destruction, the most favorable micromechanism of destruction should be considered the implementation of a highly dispersed chipping. In the third section, the effect of isothermal quenching on microstructure and mechanical properties of economically non-nickel steel 55Si3Mn2CrVMoNb is considered. It is shown that as a result of holding at 250-300 ?С, a structure of uncarbide lower bainite with a high content of residual austenite is formed in the steel. This structure provides a high complex of strength, ductility and impact strength, which is usually characteristic of steels containing nickel. In the fourth section, the operating properties of diffusion layers, obtained by saturation of steels with 0,45 % C, 1 % C and the steels for dies 3Cr2W8, 4Cr5W2VSi, Сr12Mo, Сr12V by titanium and combined with chromium and titanium, are investigated. It has been established that the durability of coatings depends on the composition of steel, saturated mixture and the type of activating additives. The highest coefficients of relative wear resistance were obtained for steels 1 % C and Сr12Mo, in which the thickness of the carbide layer was maximal. In the fifth section the results of researches of the substructure of steel 50CrNi after thermocyclic treatment with variable temperature parameters and its mechanical properties are given. The contribution of various mechanisms of strengthening to the value of the yield limit is calculated. The dominant mechanisms of hardening, which are activated during thermocyclic treatment, are found.

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Єфременко Василь Георгійович
Іващенко Вікторія Юріївна
Бурова Дар'я Володимирівна
Гаврилова Вікторія Григорівна
Григор'єва Марія Олексіївна
Зурнаджи Вадим Іванович
Малінов Леонід Соломонович
Малишева Інна Юхимівна
Олійник Інна Михайлівна
Рябікіна Марина Анатоліївна
Самотугіна Юлія Сергіївна
Чейлях Олександр Петрович

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2020-04-02