Study on heredity of shrinkage holes in continuous casting slab

doi:10.13228/j.boyuan.issn1001-0963.20240269

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Journal of Iron and Steel Research ›› 2025, Vol. 37 ›› Issue (5) : 590-597. DOI: 10.13228/j.boyuan.issn1001-0963.20240269

Smelting and Working

Study on heredity of shrinkage holes in continuous casting slab

JIANG Dongbin¹, XIE Xin², WU Chenhui², REN Ying¹, ZHANG Lifeng³

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Abstract

The mechanical properties of rolled plate will be significantly reduced if the shrinkage holes of continuous casting slab are not completely healed during rolling process. With the samples from slab, intermediate slab, and plate of E355 pipeline steel, the industrial computed tomography (CT), scanning electron microscope (SEM), and optical microscope were applied to analyze the shrinkage holes evolution in the rolling process. The results show that the slab surface layer has a dense solidification structure, where the shrinkage hole appears to be small size and single type. With the distance from the slab surface increasing, the number density of shrinkage holes rises, the size is enlarged, and it becomes the through type holes. The number density of shrinkage holes in the slab center is 5.510 mm^-3, the volume rate increases to 2.191‰, and the average and maximum sizes are 0.140 and 1.493 mm, respectively. After rough rolling process, the shrinkage hole extends along the rolling direction, the size decreases, and the number density increases. In the center of the intermediate slab, the number density is 61.744 mm^-3, the volume ratio is 0.395‰, and the maximum and average diameters are 0.038 and 0.023 mm, respectively. No large-size holes are found in the final plate, and the shrinkage holes are completely welded during finishing rolling, but the small-size holes are still observed near the MnS inclusions.

Key words

slab / intermediate slab / plate / shrinkage hole / heredity

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JIANG Dongbin, XIE Xin, WU Chenhui, REN Ying, ZHANG Lifeng. Study on heredity of shrinkage holes in continuous casting slab[J]. Journal of Iron and Steel Research, 2025, 37(5): 590-597 https://doi.org/10.13228/j.boyuan.issn1001-0963.20240269

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