Návrh chladících sekcí pro tepelné zpracování

Design of cooling units for heat treatment

kapitola v knize

en

Microstructure and nature of grains, grain size and composition determine the overall mechanical behavior of steel. Heat treatment provides an efficient way to manipulate the properties of steel by controlling the cooling rate. Way of heat treatment depends on many aspects. One of the most important parameter is the amount of production. Another important parameter is size of products. We focus here on large production such as interstand and run-out table cooling of hot rolled strip, run-out table cooling of sheets and plates, cooling of long products at the exit from a rolling mill, cooling of rails, tubes and special profiles, continuous hardening and heat treatment lines for steel strips. In-line heat treatment is characterized by running of hot material through the cooling section. Design procedure of cooling sections for obtaining the demanded structure and mechanical properties is iterative research involving several important steps. We begin with Continuous Cooling Transformation (CCT) diagram for the selected material. Numerical simulation of cooling follows to find appropriate cooling intensity and its duration. Knowing the desired cooling intensity new cooling section is designed and tested under the laboratory conditions. From the laboratory experiments boundary conditions are obtained and tested using numerical model. When the best solution is found it is tested on the real sample and the result structure is studied. In most cases the process must be repeated as the CCT diagram is for different size of sample and the cooling rate in designed section is not constant.

Mikrostruktura oceli má významný vliv na její mechanické vlastnosti. Mechanické vlastnosti a mikrostruktura může být ovlivněna jak chemickým složením oceli, tak i tepelným zpracováním. Zvyšování obsahu legujících prvků znamená značné zvýšení ceny oceli. On-line tepelného zpracování redukuje náklady jak na legující prvky, tak i náklady na re-ohřev provalků. Ve článku jsou podrobně zkoumány různé postupy tepelného zpracování kolejnic. Kolejnice jsou tepelně zpracovány za pohybu pomocí soustavy vodních trysek. Jsou zkoumány mechanické vlastnosti kolejnic a je hodnocena mikrostruktura oceli.

Microstructure and nature of grains, grain size and composition determine the overall mechanical behavior of steel. Heat treatment provides an efficient way to manipulate the properties of steel by controlling the cooling rate. Way of heat treatment depends on many aspects. One of the most important parameter is the amount of production. Another important parameter is size of products. We focus here on large production such as interstand and run-out table cooling of hot rolled strip, run-out table cooling of sheets and plates, cooling of long products at the exit from a rolling mill, cooling of rails, tubes and special profiles, continuous hardening and heat treatment lines for steel strips. In-line heat treatment is characterized by running of hot material through the cooling section. Design procedure of cooling sections for obtaining the demanded structure and mechanical properties is iterative research involving several important steps. We begin with Continuous Cooling Transformation (CCT) diagram for the selected material. Numerical simulation of cooling follows to find appropriate cooling intensity and its duration. Knowing the desired cooling intensity new cooling section is designed and tested under the laboratory conditions. From the laboratory experiments boundary conditions are obtained and tested using numerical model. When the best solution is found it is tested on the real sample and the result structure is studied. In most cases the process must be repeated as the CCT diagram is for different size of sample and the cooling rate in designed section is not constant.

součinitel přenosu tepla, chlazení, tepelné zpracování, termočlánek, Leidenfrost, experiment, ocel, tryska, okrajová podmínka, simulace, inverzní úloha, model, kolejnice, struktura, vlastnosti, perlit

HTC, cooling, temperature, thermocouple, Leidenfrost, heat treatment, experiment, steel, nozzle, boundary conditions, simulation, inverse method, model, rail, tubes, structure, properties, perlite

2012

26.09.2012

InTech

Rijeka, Croatia

978-953-51-0768-2

Heat treatment conventional and applications

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