Experimental study of oscillation mark depth in continuous casting of steel

Abstract

Mould oscillation is needed to reduce friction and thus prevent sticking and breakout of the liquid metal during casting. However, this oscillation is known to cause surface defects in the solidified steel slabs, so called oscillation marks. In this paper, the depth and the depth variation of these oscillation marks were studied using a two-level full factorial experiment (2) with four additional centre point runs. Four factors were studied: stroke length of the mould, oscillation frequency, motion pattern (strip factor) and casting speed. The stroke length affected the depth of the marks the most, where larger strokes created deeper marks. The interaction between the oscillation frequency and the strip factor of the mould also affected the oscillation mark depth. The oscillation mark depth variation was also increased by increased stroke lengths and at higher oscillation frequencies. The largest effect on the oscillation depth variation was found for the interaction between the stroke length and the oscillation frequency.

Keywords:

• Two-level factorial design
• Continuous casting experiment
• Continuous process
• Analysis of variance
• Design of experiment

Acknowledgements

The financial support from the European Union and Produktion Botnia is gratefully acknowledged. The authors thank SSAB and the engineers working on the continuous casting process for the contributions to the results presented here. Special thanks to L. Ahlström and C. Nilsson at SSAB for their valuable contributions.