(p127) Experimental und numerical investigations on cooling efficiency in the secondary cooling zone during continuous casting of steel

摘要

Cooling strategies in continuous casting of steel can vary from rapid cooling to slow cooling, mainly controlled byadjusting the amount of water sprayed onto the surface of the product. Inadequate adjustment however can lead tolocal surface undercooling or reheating, leading to surface and inner defects.This paper focuses on secondary cooling during continuous casting of steel and the experimental and numericalprediction of surface temperature distributions over the product width. The first part of this publication explains thedetermination of heat transfer coefficients (HTC) on laboratory scale, using a so called nozzle measuring stand(NMS) at the Chair of Ferrous Metallurgy (CoFM), Montanuniversitaet Leoben (MUL). Based on measured waterdistributions and determined HTC's for air-mist nozzles using the NMS, surface temperatures are calculated by atransient 2D-model for a steel plate moving at constant velocity, explained in the second part of this paper.Simulations are carried out varying water impact density and spray water distribution, consequently influencing thelocal HTC distribution over the product width. Furthermore, these results will be interpreted with regard to theirconsequence for surface and internal quality of the cast product. The results reveal the difficulty of correctadjustment of the amount of sprayed water, concurrent influencing water distribution and thus changing HTCdistribution and surface temperature, as will be shown in the end of this publication.