ShEREMET V. Scientific fundamentals of technology for longitudinally divided reinforcement

. Object is the process of structure formation during new low-carbon low-alloyed semikilled steels cooling and the parameters of the technology of thermal-mechanical strengthening of longitudinally divided reinforcement for concrete structures of strength classes А400С and А500С. The purpose is elaboration of scientific fundamentals and parameters of the industrial technology of thermal-mechanical strengthening of reinforcement rolling of the classes А400С and А500С, cooling devices for its realization and introducing them into practice in the condition of the combine "Krivorizhstal". The methods are chemical, differential-thermal, metallographic examinations; electron-microscope investigations of fine structure on a ray; quantity structure analysis; mathematic simulation of thermal exchange processes, mechanical tests of reinforcement for concrete structures and welded joints made from reinforcement, corrosion tests of reinforcement for concrete structures in various environment. In the dissertation the main regularities of structure formation processes are established, and for the first time the CCT (continuous cooling transformation diagrams) of semikilled steels with carbon contain 0,20... 0,34 % and of СтЗпс steel, which are used at the combine "Krivorizhstal" for longitudinally divided reinforcement of strength classes А400С and А500С manufacture, and also of СтЗсп steel with boron, have been built; the correlation dependences on chemical composition of industrial heats and mechanical properties of thermal hardened reinforcement for concrete structure rolling have been obtained. The technology of thermal-mechanical hardening of longitudinally divided reinforcement for concrete structure rolling of strength classes A400C and A500C and new cooling device for this technology realization are introduced into practice at condition of the combine "Krivorizhstal"; the results of the work are used in elaboration of the state standard ДСТУ 3760-98 "Прокат арматурный для железобетонных конструкций ". Efficiency: actual annual economic effect from elaborations introducing into practice only in 2002 year constituted 23.483.539,76 grivn. (author's ratio is 650.000 grivn.); increasing of competitiveness of home-grown reinforcement for concrete structures rolling of strength classes A400C and A500C at the expense of increasing of mechanical properties stability. Range of usage: the enterprises, which produce thermal hardened rolled sections, and reinforcement for concrete structures sections.