Regular Article

Mathematical model for prediction of hydrogen pick-up of liquid steel during filling of a continuous casting tundish

Department of Metallurgical and Materials Engineering, Engineering School, Federal University of Minas Gerais, Ave. Presidente Antônio Carlos, No. 6627, Belo Horizonte, Minas Gerais 31270-901, Brazil

^* e-mail: bernardombraga@hotmail.com

Received: 20 October 2017
Accepted: 4 January 2018

Abstract

Steels for several applications, such as steel cord for tires and heavy plates, present severe hydrogen restriction in their chemical composition. However, the hydrogen content of the liquid steel usually increases during tundish filling. This phenomenon, known as hydrogen pick-up, occurs due to direct steel contact with humidity present in the lining refractory, ladle sand and atmospheric air. The present work investigated by means of an analytical mathematical model the magnitude of hydrogen pick-up promoted by steel-air interaction. The relative importance of this mechanism was evaluated comparing the predictions with industrial data of hydrogen pick-up for a specific microalloyed steel grade. Results showed that air contamination can contribute to approximately 40% of the total hydrogen pick-up. An appropriate tundish inertization, which eliminates completely the air contamination, would be able to reduce approximately 1.5 ppm from the total hydrogen pick-up that happens during the beginning of the first heat of a sequence. As a consequence, it would be reduced more than 0.20 ppm of the total hydrogen pick-up in 36t of the steel cast.