In-line heat treatment of flat products

conference paper

English

An in-line heat treatment of rolled materials is becoming frequently used by hot rolling plants. This method achieves the required material structure without the necessity of reheating. This paper describes a design procedure of spray cooling sections for obtaining demanded structure and mechanical properties of steel flat products. The design involves several important parts. First, it is necessary to obtain boundary conditions for the numerical model. Several types of nozzles are tested and dependences of the heat transfer coefficient on the surface temperature are obtained. After that, the cooling process is simulated using obtained boundary conditions. The required cooling regime and appropriate type and size of nozzles are selected with the knowledge of the CCT diagram and simulations results. The selected heat treatment regime is then validated on the small sample quenching test. The regime is modified if it is necessary. Finally, the full scale sample is heat treated on the new experimental stand which was developed at the Brno University of Technology. This experimental stand allows cooling of the moveable sample by two types of nozzles. First, it is cooled by intensive spray for short time period and then it is cooled by soft spray. The stand is able to stop the cooling and temper the sample. This paper presents laboratory results of the heat treatment of S355 steel which was spray quenched and self-tempered (the hot core tempers the quenched outer part) at the temperature 600 °C.

Keywords: heat treatment, quenching, spray cooling, heat transfer coefficient

HORSKÝ, J.; HNÍZDIL, M.; CHABIČOVSKÝ, M.; KOTRBÁČEK, P.

11. 5. 2016

Asociace pro tepelné zpracování kovů

Čerčany

978-80-904462-9-8

Proceedings European Conference on Heat Treatment 2016 and 3rd International Conference on Heat Treatment and Surface Engineering in Automotive Applications, 11 – 13 May 2016, Prague, Czech Republic

1

8

8