Q420C小方坯角部裂纹控制

Corner Crack Control in Casting and Rolling of Q420C Steel Square-billet

针对弧半径6 m、断面180 mm方坯连铸机生产的Q420C含铝连铸坯存在角部裂纹缺陷的问题展开研究,从铸机弧半径、钢中AlN析出两个角度进行了分析。结果表明,铸机弧半径小,矫直应力过大是铸坯角部产生裂纹的主要原因;AlN在钢液凝固析出时,钉轧在晶界处,易产生角部裂纹。通过控制钢中N含量,降低浇注过程中的冷却强度,使其矫直温度≥950℃,可以避免AlN的大量析出,缓解了铸坯角部裂纹的产生,使Q420C角钢轧材开裂率降低8%。

The comer crack defects in Q420C containing Al billet were produced by arc radius 6 m and section 180 mm continuous casting caster. The angles of casting machine radius of arc and precipitation AlN in steel were analyzed. The results show that the crack at the billet comer main reason is due to the small radius of the caster. When molten steel solidifies, AIN is precipitated out in the grain boundary and produces angular cracks easily. By controlling the N content in the steel, reduce the intensity of cooling, the straightening temperature keep great than 950 ℃, it will be avoid a lot of AlN precipitation, alleviates the slab comer crack, and the cracking rate of Q420C angle rolling steel can be reduced 8%.