VDEh-Betriebsforschungsinstitut GmbH, Düsseldorf, Germany:

Torsten Lamp, Dr., project group leader casting and solidification, torsten.lamp@bfi.de

Herbert Köchner, Dr., head of department, Dept. Measuring techniques for metallurgical processes

ArcelorMittal Ruhrort GmbH, Duisburg, Germany:

Siegfried Schiewe, Dipl.-Ing., continuous casting manager

Dieter Kirsch, Dipl.-Ing., head of steelplant

Thomas Schramm, Dipl.-Ing., continuous casting manager

Naga Rajesh Puvvada, Dipl.-Ing., co-ordinator development projects

Peter Janßen, Dr., head of quality department 

A non-uniform solidification of the strand in the mould and during the secondary cooling process is one of the main reasons for crack formation. Especially peritectic steel grades are sensitive to crack formation. The continuous characterization of the mould flux cover on the meniscus helps to stabilize and optimize the initial solidification in the mould. The strand surface temperature is monitored after the individual cooling zones inside the secondary cooling area. The monitoring is based on the principle of area resolution and works continuously. It gives directin formation on the homogeneity and efficiency of the spray cooling system. Both monitoring systems are used for the identification of process conditions which tend to higher crack formation. The publication gives an overview onthe industrial application and the first operational results. An on-line strand surface temperature monitoring system and a system for the characterization of mould flux cover were developed. Both systems were built up, tested and installed in the plant. Plant trials of the mould flux cover monitoring system showed complex interactions between stirring, mould flux cover and melt. With stereo imaging sensors and image adopted processing software it isnow possible to detect upcoming mould flux cover breakups, their frequency, their intensity and their position over the whole mould area. An installed traffic light warning system is an advisor for operators. The strand surface temperature monitoring system was installed at two positions in the secondary cooling zone area. The build up of asymmetric temperature profiles with different cooling water through put could be detected. The asymmetric temperature distribution was approximately equalled by reheating as far as the subsequent cooling zone. This asymmetric temperature profile cannot be detectedby a temperature measurement after the end of the secondary cooling box.

1. Lamp, T.; Köchner, H.: stahl u. eisen 129 (2009) No. 7, p. 69/72.