厚板坯角部凹陷裂纹的控制措施

Control measures for dented cracks at corners of thick slabs

角部凹陷裂纹是厚板坯连铸生产中常见的质量缺陷,随着板坯厚度的增加,角部凹陷裂纹发生率不断提高,已成为制约厚板坯质量提升和品种开发的重要因素。针对260 mm×2800 mm、320 mm×2800 mm断面板坯,研究了角部凹陷裂纹出现的位置、形貌及组织,分析了铸坯角部在结晶器内的凝固收缩行为的影响因素,获得了厚板坯角部凹陷裂纹控制方法。通过研发曲面窄面铜板结晶器,适应坯壳在结晶器中的收缩;增加窄边足辊对数延长二冷区冷却时间;提高保护渣黏度以增加结晶温度和传热性能;调整结晶器振动参数等控制措施,有效解决了厚板坯角部凹陷裂纹的难题,260 mm×2800 mm与320 mm×2800 mm角部凹陷裂纹的发生率分别降低至0.41%和0.86%,为板坯热装热送创造了有利条件。

Corner dent cracks are a common quality defect in the production of thick slab continuous casting.With the increase of slab thickness,the incidence of corner dent cracks continues to increase,which has become an important factor restricting the quality improvement and variety development of thick slabs.For slabs with 260 mm×2800 mm and 320 mm×2800 mm sections,the position,morphology and structure of the depression cracks in the corners were studied,the influencing factors of the solidification and shrinkage behavior of the slab corners in the mold were analyzed,and the control method of corner depression crack was obtained.Through the development of curved narrow surface copper plate mold,adapt to the billet shell shrinkage in the mold.The cooling time of secondary cooling zone is prolonged by increasing the logarithm of narrow edge foot roll.The crystallization temperature and heat transfer performance can be increased by increasing the viscosity of the slag.Control measures such as adjusting mold vibration parameters effectively solve the problem of corner sag crack in thick slab,and the incidence of dented cracks at the corners of 260 mm×2800 mm and 320 mm×2800 mm was reduced to 0.41%and 0.86%,which creates favorable conditions for hot loading and hot sending of slab.