扁鋼胚連續鑄造技術發展及內部品質改善成效

DEVELOPMENT OF SLAB CONTINOUS CASTING TECHNOLOGY AND IMPROVEMENT OF INTERNAL QUALITY

陳勝榮(Seng-Jung Chen)

《鑛冶：中國鑛冶工程學會會刊》 26卷2期 (1982/06) Pp. 53-62

https://doi.org/10.30069/MM.198206_26(2).0005

摘要

扁鋼胚連續鑄造所遭遇主要之内部品質問題，為（1）中心線裂及（2）縱斷面内部裂。中心線裂是因鑄胚接近完全凝固之部份有凸起之現象，或此部份之液心受到不當之擠壓，因此機器之狀況實為中心線裂之主要影響因素。目前除以硫印判斷中線裂之外並以超音波偵測鑄胚之内部，除可控制品質之外並有檢測機器之功能。縱斷面内部裂是因鑄胚於鑄道内受到不當之矯直或擠壓應變。裂縫起源於鑄胚內部之液態－固態交界面，而沿着柱狀晶之界面延伸成長，直至應力消失為止。鋼中C含量大於0.17％以上，Mn/S比值小於40，澆鑄中之遇熱度大於15°C時，都會使鑄胚對内裂之敏感性增加。針對以上之缺陷，首先研究其生成機構，再採取適當之冶金條件及機械條件並改進連鑄之技術，現已足以有效遏止缺陷之發生。

並列摘要

Two major internal defects encountered in continuous casting slab are internal cracks (half way cracks) and centreline cracks. Centreline cracks caused by the bulging of the strand or unproper rollers suppressed at the point of complete solidification. Therefore the machine factors are the primary driving force to cause the centreline cracks. Besides sulphur print, the ultrasonic test are used to inspect and control the internal quality of the slabs, which also have the function to check the condition of the slab casters. The internal cracks are initiated at the liquid-solid interface in the slab during cooling, then propagated along the portion of interdendrite until the stress vainshed. If the carbon content in steel greater than 0.17%, Mn/S ratio approximately lower than 40, and the superheat of molten steel higher than 15°C, the steel becomes more sensitive for cracks formation. Through carefully study the mechanism of cracks formation, suitable metallurgical critera, mechanical conditions and technical improvement are adopted to effectively prevent the formation of internal defects that mentioned above.