热轧H型钢边部裂纹成因分析

Cause Analysis on Edge Crack of Hot-rolled H-shape Steel

某型钢厂生产规格为H300 mm×150 mm×12 000 mm、钢种为Q235B的H型钢,成品多存在边部裂纹。通过宏观形貌观察、化学成分、金相分析以及扫描电镜微区分析,得出:边部裂纹由短线状Mn/S夹杂及颗粒状氧化硅夹杂引起的负偏析带开裂造成。

A steel section plant manufactures the H shape steel with specifications of H300 mm × 150 mm × 12 000 mm and steel grade Q235 B,most of the final products have edge cracks. Through the macroscopic observation,the chemical composition analysis,the metallographic analysis and the scanning electron microscopy（ SEM） microanalysis,it is concluded that the edge crack is caused by the negative segregation zone which is caused by the short line Mn/S inclusions and granular silicon oxide impurities.