Metall. Res. Technol.
Volume 112, Number 6, 2015
|Number of page(s)||12|
|Published online||07 December 2015|
Characteristics of subsurface inclusions in deep-drawing steel slabs at high casting speed
School of metallurgical and ecological engineering, University of
Science and Technology Beijing, No.30 Xueyuan Road, Haidian District, Beijing
2 State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, No.30 Xueyuan Road, Haidian District, Beijing 100083, P.R. China
3 Shougang Research Institute of Technology, No.69, Yangzhuang Street, Shijingshan District, Beijing 100043, P.R. China
4 Shougang Jingtang Iron and Steel Co. Ltd. Caofeidian District, Tangshan 063200, P.R. China
Received: 1 July 2015
Accepted: 19 October 2015
Deep-drawing steels are widely used in the automobile industry and macro-inclusions in continuous casting slabs should be strictly controlled because they cause surface defects in the final products. In this paper, industrial tests with different casting speeds from 1.0 m.min-1 to 2.5 m.min-1 and different tundish superheats were carried out, then subsurface inclusions in high-speed casting slabs were investigated with a large detection area by the ASPEX automatic inclusion analysis system, and the effect of the casting speed and tundish superheat was studied. The results show that there are six different types of macro-inclusions found beneath the slab surface, named cluster alumina, bubble plus cluster alumina, lump alumina, cluster TiOx-Al2O3, entrapped mold powder and CaO-Al2O3-MgO, respectively. The above first three types account for about 98% of total inclusions in the slabs cast with the mold fluctuation within ±3 mm. The size of more than 80% of such inclusions ranges from 20 to 50 μm. The number density of inclusions larger than 50 μm decreases with the increase in the casting speed and tundish superheat. The subsurface macro-inclusions in deep-drawing steel slabs are closely related to the hook structure. Increasing the casting speed and superheat is effective for reducing the hook depth and large-sized inclusions on the subsurface of slabs.
Key words: High-speed casting / non-metallic inclusions / hook structure / deep-drawing steels / continuous casting
© EDP Sciences 2015
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