S355J2钢板表面裂纹分析

ANALYSIS ON THE SURFACE CRACKS OF S355J2 PLATES

针对南钢中厚板卷厂生产的S355 J2钢板表面出现裂纹缺陷,采用光学显微镜、扫描电镜和能谱仪进行了分析。结果表明,裂纹具有沿钢板纵向延伸且深度很小的规律性,裂纹产生的原因主要是Nb元素的碳氮化物表面偏聚所致。通过进行微钛处理的成分设计并结合优化连铸工艺可以有效改善S355 J2钢板表面裂纹问题。

The surface cracks of S355J2 plates produced by Nanjing Iron ＆ Steel Group Co. , Ltd. were analyzed by using optical microscope SEM and energy spectromete. The results showed that cracking always propagates along the length of plate and locates more closer to plate surface. The cracks were caused by the aggregation of Nb（ C, N） at surface in plate. Through adopting Ti microalloying technology and optimizing continuous casting process, the surface qualities were improved effectively.