Abstract: The surface micro cracks of 25 mm hot rolled plate rolled by cast slab of C-Mn steel(0.13～0.20C, 1.00~1.60Mn,0.09Cu,0.07As,0.05Sn)have been studied by scanning electron microscope and X-ray energy dispersive spectrometer.Results showed that there was thin oxidizing-decarburizing layer at both sides of surface crack,the crack fractured along grain-boundary and the low-melting-point Cu-As-Sn enriched phases existed at steel matrix near crack.In production practice,as Cu,As,Sn content in steel was respectively controlled ≤0.02%,the surface net cracks of hot rolled plate were basically eliminated.

Key words: Cu,As,Sn,C-Mn Steel,Hot Rolled Plate,Surface Crack,Low-Melting-Point Enriched Phase

摘要： 通过扫描电子显微镜和X-射线能谱分析研究了C-Mn钢(%:0.13～0.20C、1.00～1.60Mn、0.09Cu、0.07As、0.05Sn)连铸坯热轧的25 mm板表面微裂纹。结果表明,热轧板表面裂纹两侧存在薄的氧化脱碳层,裂纹沿晶界开裂,裂纹附近的基体处存在Cu、As、Sn低熔点富集相。实际生产中当钢中的Cu、As、Sn含量分别控制≤0.02%,可基本消除热轧板表面网状裂纹。

关键词: Cu、As、Sn, C-Mn钢, 热轧板, 表面裂纹, 低熔富集相