Minimization of surface defects by increasing the surface temperature during the straightening of a continuously cast slab
Zmanjševanje površinskih napak z zvišanjem temperature površine kontinuirno ulitega slaba med ravnanjem

english

2013

volume 47, issue 3

Inštitut za kovinske materiale in tehnologije
(Obvezni izvod spletne publikacije)

Surface temperatures of cast slabs on small-radius segments as well as on the unbent areas belong to the parameters that affect the surface quality of continuously cast slabs. Older machines for continuous casting were designed with regard to the quantity (the amount of cast slabs) rather than the quality of the production. Therefore, an adaptation of the secondary cooling is required in order to obtain the desired surface temperatures. The modification consists of a dynamic control of the secondary cooling, surface-temperature monitoring by means of a numerical model of the temperature field as well as a prospective replacement of the cooling nozzles. In order to optimize and control the secondary cooling, characteristics of the nozzles, especially the influences of the water-flow rate, air pressure, casting speed, surface temperatures and heat-transfer coefficient under the nozzles have to be known. Moreover, the heat-transfer coefficient can also be influenced by the age of the nozzles. The paper deals with the relationships between these influences and their impacts on the temperature field of a cast slab. The results are presented for the 1530 mm x 250 mm slabs that are cast in Evraz Vítkovice Steel where the main author's dynamic, 3D solidification model is used, in its off-line version, to control the production interface. The results can be used for the preparation of a real casting process.

09.05.2014