Q240B角钢腿部裂纹形态分析及成因探讨

分析了Q240B角钢腿部裂纹处的化学成分、微观形貌、金相组织及其形成原因，发现引起该裂纹的原因一是轧制过程中的热划伤，二是连铸坯中存在硅酸盐类夹杂物表面裂纹、表面气泡等缺陷，对此分别采取保证导卫安装质量和改进导卫材质、提高冶炼质量以减少各类夹杂物、增加轧制时的压缩比和粗轧翻钢道次等措施后，铁塔角钢的产品合格率由88.5%提高到97.5%，成材率由78.5%提高到93.4%

Study on Cracks Shape on the Top-leg of Q420B Angle Steel and Its Formation Causes

The chemical composition,shape and microstructure of crack on the top-leg of Q420B angel steel were analyzed.The formation causes of crack were scratch of hot rolling and inclusion,facial crack and bubble of casting billet.Therefore,the countermeasures were put forward,such as improving steelmaking quality, increasing rolling reduction,assuring guide and guard installation quality,etc.At last,the rate of qualified products was increased from 88.5%to 97.5%,and the yield increased from 78.5%to 93.4%.