含硼普碳钢表面纵裂纹控制

安钢生产的含硼普碳钢宽板坯出现大量表面纵裂纹，为降低其对产品质量的影响，对其产生原因进行了理论分析和生产试验研究，结果表明，引起含硼普碳钢宽板坯纵裂纹的原因是结晶器内钢中B在树枝晶晶界偏析和钢质带来的凝固坯壳厚度差异，以及凝固坯壳收缩不均匀和拉速波动导致坯壳开裂。通过优化转炉脱氧工艺、调整硼合金加入时机和加入量、制定合理的结晶器冷却制度、改进拉速控制和液面操作等措施，降低了含硼钢铸坯的裂纹发生率，提高了产品质量和铸坯合格率。

CONTROL MEASURES OF LONGITUDINAL CRACK ON THE SURFACE OF PLAIN BORON CARBON STEEL

Numerous longitudinal cracks appeared on the surfaces of the wide plain boron carbon steel slab made in Anyang Steel .To reduce their influence on products quality , we analyzed theoretically the causes and made production experiments .The results show that the causes of the cracks on steel surfaces are that there are slab solidification shell thickness differences , which are caused by boron boundary segregation in the branches of crystal grain in mold and the quality of molten steel , and also uneven contraction of slab solidification shell and casting speed fluctuation .Through such measures as optimizing converter de-oxidation process , adjusting the addition amount and time of boron alloy , working out reasonable mold cooling regulation , improving the casting speed control and mold level control etc ., the crack ratio of boron steel is reduced , and both product quality and cast slab qualification rate are enhanced .