DEVELOPMENT OF PILOT BATCH AND GRADE ESTIMATION OF COILS OF STEEL GRADE S355MC AT ROLLING MILL "1700", PJSC "ILYICH IRON AND STEEL WORKS"

Development of technology of hot rolling coils using thermo- mechanical controlled process for the wide-strip rolling mill and grade estimation of coils

Estimation of crack progration dynamics in WWER-1000 core barrel taking into account combined effect of high temperature, static loading and neutron irradiation

Розглянуто питання про поширення тріщини в шахті водо-водяного ядерного реактора ВВЕР-1000. Побудовано рівняння швидкості поширення тріщини в матеріалі за сумісної дії високої температури, силового навантаження та нейтронного опромінення, що добре описує результати експериментальних досліджень. На його основі побудовано модель визначення залишкової довговічності елемента при заданій конфігурації тріщини. Модель застосовано для визначення залишкового ресурсу паропроводу першого контуру реактора типу ВВЕР-1000 з поверхневою тріщиною та прогнозування динаміки поширення поверхневої тріщини в шахті такого реактора.Reactor in-core components is subjected to high radiation doses that results in change of form and swelling during operation. Inside pressure of baffle on core barrel in zone of contact in WWER-type reactors creates additional stresses. Residual welding stresses can also significantly effect a level of stressed state of core barrel wall. High stresses combined with in-core temperature can cause growing of initial micro defects which can lead to rapid crack growth. That should be considered in estimation of working capacity of vessel internals for extension of WWER-1000 reactor service life. It is also important to take into account influence of neutron irradiation on material properties which can increase cracking rate. Aim of present work is to build general mathematical model of creep cracking which includes neutron irradiation influence, and apply it to reactor core barrel to see what happens with macro crack which is formed during service life of reactor. Base model for predicting crack growth of loaded cracked plate under influence of high temperature and neutron irradiation was build using second thermodynamics law modification for cracked body. It has been suggested that main mechanism of cracking is high-temperature creep crack growth. Neutron damage only increase creep rate which was shown in experimental investigations [5]. According to that we use creep law, and describe crack tip opening displacement rate like function of neutron damage. That function was used to describe one cycle of stepwise slow cracking process. All components were rewritten in terms of crack tip opening displacement. Adding initial and final condition equations to energy rate balance function extended for all time period forms finished model for predicting crack growth dynamics and estimating residual life in cracked plate under aforementioned conditions. Base model was further developed for case of plane crack in spatial body, and applied to reactor core barrel with initial longitudinal crack. It was shown than neutron irradiation significantly effect the creep crack growth level in the core barrel wall, that should be considered in estimation of working capacity of vessel internals at extension of service life of WWER-1000 reactor

Calculation method and simulation of work of the ring elastic compensator for sheet-forming

The design of the elastic ring compensator of «press-and-die” system errors, the method and software for calculating its geometric parameters are given in the article. The developed method is based on the account of unevenness of the radial and altitudinal deformation (barrel-type shape) of the elastic working element made of polyurethane. A specific example of computer implementation of the developed mathematical model for calculating the sizes of such a compensator for steel-forming operations on an open-crank press is made. Approbation of the compensator was carried out in industrial conditions

Refinement issue of displaced volume at upsetting of cylindrical workpiece by radial dies

By analyzing the problem of upsetting of a workpiece by radial dies, an improved solution for determining the displaced volume was obtained. The value of the displaced volume is the basis for calculating such an important technological criterion as the engineering strain range of the workpiece during the upsetting. It is revealed that the main difficulty lies in calculating the volume that is placed between the contact surface and the end protuberances of the deformed workpiece, which requires the involvement of numerical or tabular integration methods that do not provide a complete solution

Refinement issue of displaced volume at upsetting of cylindrical workpiece by radial dies

By analyzing the problem of upsetting of a workpiece by radial dies, an improved solution for determining the displaced volume was obtained. The value of the displaced volume is the basis for calculating such an important technological criterion as the engineering strain range of the workpiece during the upsetting. It is revealed that the main difficulty lies in calculating the volume that is placed between the contact surface and the end protuberances of the deformed workpiece, which requires the involvement of numerical or tabular integration methods that do not provide a complete solution

Spring-back effect during multi-pass bending of sheet blanks

A significant factor, which leads to the discrepancy of the final sizes of the bent sheet parts to their drawings is the springing of the sheet blank during bending. At the same time, the springing during multi-pass bending is not sufficiently studied. The purpose of the work is to obtain the graphical and mathematical dependencies for descriptions of the resultative spring-back angle of the blanks at the multi-pass bending, taking into account the width of the blank, number of passes, and pre-bending angle at each preliminary pass. The paper describes the basic information about the difference between the spring-back angle for one-pass or multi-pass bending. In the course of the study it is shown that during calculations of forming and preventive prediction of the geometric quality of bending shapes it is necessary to take into account properties of the blank material, as well as the angles of the prebends and the width to thickness ratio of the blank. A methodology of experimental research was developed for determining the spring-back angle during multi-pass bending in three bending dies with 109°, 91° and 72° pass-by-pass reducing angles

Calculation method and simulation of work of the ring elastic compensator for sheet-forming

The design of the elastic ring compensator of «press-and-die” system errors, the method and software for calculating its geometric parameters are given in the article. The developed method is based on the account of unevenness of the radial and altitudinal deformation (barrel-type shape) of the elastic working element made of polyurethane. A specific example of computer implementation of the developed mathematical model for calculating the sizes of such a compensator for steel-forming operations on an open-crank press is made. Approbation of the compensator was carried out in industrial conditions

Contact-deformation mechanism of boundary friction

Research was conducted to determine the effect of lubricants on stress and strain in the contact of metal surfaces. Experiments were carried out on the introduction of a fixed and moving indenter in contact with a dry and lubricated surface.The steel spherical specimen was pressed into a lubricated and dry metal surface. The microstructures of the structure of the surface layer are studied under various conditions of deformation. The diagrams of the relative deformation of the surface layers are constructed. The mechanism of the formation and distribution of internal stresses for dry and greased contact is described. Experimental studies of the introduction of a moving steel indenter into a lubricated surface have been carried out. The relationship of the deformation mechanisms of lubricated surfaces with their wear resistance is determined. The results obtained are recommended for predicting the durability of lubricated friction units according to the criterion of contact strength