采用宏观检验、化学成分分析、金相检验、扫描电镜及能谱分析的方法, 对Q235钢板表面纵裂纹的产生原因进行了分析。结果表明: 裂纹附近组织存在脱碳现象, 且裂纹附近基体中分布有颗粒夹杂物, 除了裂纹内部主要含铁的氧化物, 基体附近中还存在硅和锰的二次氧化颗粒以及钠元素, 说明此类裂纹是在连铸结晶器中形成的, 最终在钢板表面形成裂纹。

The formation causes of longitudinal cracks on the surface of Q235 steel plate were analyzed by macrographic examination, chemical composition analysis, metallographic examination, scanning electron microscopy and energy spectrum analysis. The results show that: the decarburization phenomenon existed in the structure around cracks, and particle inclusions existed in the matrix around cracks. Besides the iron oxides inside cracks, secondary oxides of silicon and manganese were found in the matrix as well as sodium element. It was proved that the cracks were generated in the continuous casting crystallizer and eventually formed on the surface of the steel plate.