通过金相观察、扫描电镜和XEDS分析,对低合金钢连铸板坯轧制中板出现的表面微裂纹进行研究,发现裂纹附近存在Cu和As元素,裂纹沿晶界延伸,确定钢中的Cu、As和Sn等元素在γ晶界偏聚和选择氧化在钢基体和氧化铁层间形成含Cu、As和Sn的富集相,钢的塑性恶化是导致中板表面微裂纹的主要原因。分析了Cu、As和Sn对表面微裂纹的影响机理,提出了相应的防止措施。 Through the observation of metallographic observation, scanning electron microscopy and X-ray photoelectron spectroscopy (XRD), the surface microcracks appeared in the low alloyed steel slab during rolling were studied. It was found that Cu and As were present in the vicinity of the crack and the cracks extended along the grain boundaries, Segregation and selective oxidation of Cu, As and Sn at the γ grain boundaries Formation of a rich phase containing Cu, As and Sn between the steel substrate and the iron oxide layer. The plastic deterioration of the steel is the main cause of the microcrack on the surface of the medium plate . The mechanism of the effect of Cu, As and Sn on the surface microcracks was analyzed and the corresponding preventive measures were put forward.