連鑄扁鋼胚形成熱軋鋼捲孔洞原因之研究及其改善成效

Study of holes in hot rolled strip from continuously cast slabs and its elimination

陳勝榮(S. J. Chen) ； 林東毅(D. Y. Lin)

《鑛冶：中國鑛冶工程學會會刊》 31卷1期 (1987/03) Pp. 123-134

https://doi.org/10.30069/MM.198703_31(1).0012

摘要

中鋼熱軋廠自71年2月開工以來，卽受鋼捲中央不連續性大型孔洞所困擾，導致鋼品剔退，甚至鋼捲斷帶、中斷生產，耗費修復工時及人力至鉅。為解決此項存在已久之鋼捲品質大患，吾人雖經廣查文獻，均未有孔洞之形成機構及改善資料可供參考，遂自行設計一套完整之試驗方法，針對鋼種成分特性、鋼胚表面、内部品質、扁鋼胚連鑄製程條件及其冷却方式全面探討；在大量試驗下，發現（1）扁鋼胚之酸洗内裂乃熱軋鋼捲孔洞之來源（2）當碳鋼之［N］含量大於80 ppm時，便有軋延孔洞之危險（3）紅熱扁鋼胚之水冷作業對孔洞之發生有極不利之影響。進而建立一套完整之扁鋼胚酸洗内裂至熱軋鋼捲孔洞之形成模式。本文旨在闡明此項試驗、結果及孔洞之形成模式，並針對上述缺陷成因，改變連鑄扁鋼胚之製程冷却條件，終能有效解決此項懸宕已久之缺陷，提高產品產率及合格率。

並列摘要

Rolled holes have been considered to be the big problem in CSC's Hot Strip Mill since it was set-up in Feb. 1982. They happened discontinuously at the center of the coil and usually caused the product rejection, coil fracture and even the HSM shut-down, which wasted much production time and man power to repair it. To solve the chronic problem and the remedy of the hot rolled holes, even though with the lack of published information about the formation mechanism, we made a series of experiments to figure out the relationship between the rolled holes and following factors such as steel composition, slab's surface and internal qualities, casting process parameters and slab's cooling mode. After a lot of experiments we found that (1) slab's internal cracks revealed by macroetching are the sources of hot rolled holes (2) it is possible for rolled holes to occur if the content of [N] in carbon steel exceeded 80ppm. (3) water cooling of hot slab which is just cast is so detrimental as to cause hot rolled holes. According to these experimental results, we established that the forming mechanism ef the hot rolled hole is caused by slad's internal cracks as revealed by macroetching. This paper is to demenstrate the results of these experiments, the forming mechanism of hot rolled hole and how the modification of hot slab's cooling mode could solve this suspending problem and the remarkable improvement of yield and quality of the hot rolled coils.