钢中残余元素在连铸坯和热轧板中的富集行为

Enrichment of residual elements in continuously cast slabs and medium Plates

通过扫描电镜和X射线能谱分析仪(X-EDS)分析,对低合金钢种连铸板坯和热轧板中Cu、As和Sn的富集行为进行了研究.实验结果表明:连铸坯中氧化层和氧化层/基体层界面存在Cu、As和Sn元素同时富集现象;热轧板氧化层/基体层界面存在Cu、As和Sn元素富集相,基体层中Cu、As和Sn含量高于氧化层;热轧板晶界处Cu、As和Sn含量明显高于热轧板晶内;Cu、As和Sn在γ晶界偏聚和Fe的优先氧化造成连铸坯中Cu、As和Sn富集,加热炉的二次加热加剧Cu、As和Sn的富集程度,引起Cu、As和Sn向钢材基体渗透扩散,使钢的塑性恶化,导致中板大量表面微裂纹缺陷.分析了Cu、As和Sn富集相对表面微裂纹的影响机理.

The enrichment mechanism of Cu, As and Sn in HSLA continuously cast slabs and medium plates were studied by scanning electron microscope and X-ray energy dispersive spectroscopy （X-EDS）. It is shown that Cu, As and Sn are simultaneous enriched in the scale and the scale/steel matrix interface of continuously cast slabs. There are Cu, As and Sn enriched phases in the scale/steel matrix interface of medium plates, and the contents of Cu, As and Sn in the steel matrix are large than those in the scale. The contents of Cu, AS and Sn at grain boundaries of hot rolled plates are more than those in grains. Segregation of Cu, AS and Sn at austenite grain boundaries and selective oxidation of Fe result in enrichment of Cu, As and Sn, reheating in the reheating furnace ex- acerbates the enrichment, and the penetration and diffusion of Cu, As and Sn toward the steel matrix deteriorates the hot ductility of steel tremendously, which lead to lots of surface microcracks in medium plates. The effect meehanism of Cu, As and Sn enriched phases on the surface microcracks was analyzed.