Development of a model predicting inclusions precipitation in nozzles based on chemical composition and process parameters such as casting rate, liquid temperature, nozzle design and slag composition
During continuous casting of Al killed steels, nozzle clogging occurs due to alumina precipitation. This phenomenon is highly detrimental to casting reliability and the quality of cast products. Calcium treatment has been successfully tested to solve clogging problems by modification of alumina inclusions into low melting point calcium aluminates. Calcium treatment, on the other hand, can worsen steel cleanliness, especially if the amount of Ca is inadequate. Moreover, the presence of sulphur can lead to the formation of solid CaS inclusions, which can also be responsible for nozzle clogging. The aim of the project was to develop a mathematical model to predict inclusions precipitation in nozzles, in order to supply steelmakers with a reliable tool for a correct calcium treatment, in order to assure a good castability and also to improve steel cleanness. The model has been developed and tested by means of experimental data available from industrial scale heats. The main frame of the model and the decision criteria are described. A large number of inclusions found on samples collected in trial heats have been detected by means of optical microscopy, supported by image analysis software, and scanning electron microscopy. Results on inclusion amount and composition have been linked to castability and steel composition. The strong influence of inclusion composition and steel composition on castability has been proven. The influence of nozzle design and casting parameters on nozzle clogging and steel cleanliness has also been investigated by means of physical models and numerical computations, with reference to the continuous casting feeding system. Resulting strategies for preventing clogging have been assessed.
Bibliographic Reference: EUR 21442 EN (2005), 205 pp. Euro: 35
Availability: Katalogue Number: KI-NA-21442-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.eu/
ISBN: ISBN: 92-894-9869-2
Record Number: 200618452 / Last updated on: 2005-12-15
Original language: en
Available languages: en