Abstract: The cause for fracture of partial 22 t 170 mm x 1 650 mm x 10 000 mm casting slab of steel 25SiMn2 during crane-conveying process has been examined and analyzed. Results show that during casting the superheating extent of liquid steel in tundish is higher (30 ~36 °C) led to significant columnar crystal growth at 1/4 thickness of slab, poor fluidity of molten steel and lack back feeding during solidification, as result a lot of micro-shrinkage cavity occur causing crack at micro-shrinkage cavity by stress concentration effect and finally causing fracture of slab by repeating crane-conveying and acting with self-gravity. The fracture of casting slab is availably avoided by decreasing superheating extent of liquid in tundish to 10 ~30 ℃ and reducing times of crane-conveying of slab.

摘要： 分析了在吊运过程部分25SiMn2钢重22 t170 mm×1 650 mm×10 000 mm连铸板坯断裂的原因。结果表明,浇铸时中间包钢水过热度高(30~36℃),引起铸坯厚度1/4位置柱状晶发达,钢液凝固时流动性不好,补缩不足,出现大量显微缩孔,并在反复吊运后在自身重力作用下,显微缩孔处应力集中开裂而造成铸坯断裂。通过降低中间包钢水过热度(10~30℃) 、减少吊运次数可有效避免铸坯断裂。