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Information × Registration Number 0212U000529, 0109U002652 , R & D reports Title Development of methods for definition of serviceability of constructional materials and power eqyipment elements with ze account of hydrogen containing environment popup.stage_title Head Ivanytskyi Yaroslav Lavrentievich, Registration Date 21-02-2012 Organization Karpenko Physico-Mechanical Institute of the National Academy of Science of Ukraine popup.description2 The aim of work - creating a theoretical and experimental method of evaluation of carrying capacity of the elements of power equipment for the change in resistance to fracture of structural materials subject to operational conditions. In this work the influence of the stress-strain state on the hydrogen redistribution in the process zone and the effect of hydrogen on mechanical properties and fracture toughness parameters of materials was established; the mathematical model of hydrogen redistribution in structural elements by thermoforce load was developed and numerically implemented; software for solving elastic-plastic problem was created. Hydrostatic stress and hydrogen concentration distributions on extension of cracks during tension load at the time of crack start and after unloading for flat hydrogenated samples with a central crack and cylindrical specimens was constructed (steel 20, 65Г. 40X). It was established that the concentration of hydrogen in the process zone depends strongly on the distribution of hydrostatic stress, the maximum value is determined by strength characteristics of the material. In cylindrical specimens hydrogen concentration was in 2-3 times bigger than in the flat result specimens that is caused by complex stress state. In the unloaded specimen hydrogen concentration near the crack tip, calculated by the method of finite elements is in 2 times lower than the limit-equilibrium state, that is caused by squeezing stresses in the process zone. A new method of experimental research for determine the characteristics of strength and fracture toughness of steels under complex loading in different hydrogen concentrations was developed. Crack grows resistance of structural steels (steel 20, 12Х1МФ, 40X) at the normal tension, across and longitudinal shear in air and in hydrogen was defined. An ambiguous effect of hydrogen on the static crack grows resistance at the different mechanisms of plastic deformation of steel 20 and steel 40X. At normal tension (mode I) crack grows resistance in hydrogen of steel 40X and steel 20 decreases on 13% and 5% respectively, at longitudinal shear (mode III) decreases on 27% and 30%, at across shear (mode II) for steel 20 KIIC decreases 14%. The criterion of boundary equilibrium state of the body with a crack under complex loading at the hydrogen influence was extended and value parameters (i = 1, 2, 3) at complex loading, which are included in this criterion during practical use. The boundary equilibrium state diagram for steel 20 and steel 40X at hydrogen was building. It was shown, that hydrogen concentration in the process zone at axial tension of plate with crack made of 08кп steel increase in 3-5 times then in unstrained material. A technique for studying the processes of deformation and fracture cross-like metal specimens with the central crack in hydrogen environment was developed. That was found, when changing the stiffness of the load from -0.5 to 1.2, the start crack force Р1С and critical SIF KC vary within 30%, critical crack opening ?c at the tip of crack within the 47%, critical strain ?c in the crack tip within 40%. Research in hydrogen showed a similar character of hardness of biaxial loading influence on these characteristics depending. As a result of research by DIC method found that the zone of maximum elastic-plastic deformation before crack under biaxial loading in hydrogen is larger than in air. Product Description popup.authors Бойко Василь Миколайович Вергун Ігор Андрійович Гвоздюк Микола Мар'янович Гембара Оксана Володимирівна Гурська Руслана Василівна Дмитрів Зіновій Володимирович Квашневський Юрій Ілліч Костів Ростислав Богданович Кунь Петро Степанович Ленковський Тарас Михайлович Мольков Юрій Валерійович Чепіль Ольга Ярославівна Черниш Марія Степанівна Штаюра Степан Теодорович popup.nrat_date 2020-04-02 Close