49MnVS非调质钢水口堵塞原因分析

 非调质钢中含有较多的铝和硫，常在连铸过程中因水口蓄积钙铝酸盐或硫化钙而发生堵塞，影响生产的顺利进行。为了探究非调质钢的水口堵塞原因并提出预防措施，采用X射线荧光分析、X射线衍射分析和热力学计算，分析了非调质钢49MnVS的水口堵塞结瘤物。结果表明，水口堵塞物主要由CaO·6Al2O3、CaO·Al2O3、MgO·Al2O3和金属铁相组成，生产中钙的收得率仅为预期的53.33%；热力学计算表明，水口堵塞的原因是钢液中的钙铝质量比较低，生成了大量高熔点的CaO·6Al2O3和CaO·Al2O3夹杂物，夹杂物在水口处黏附聚集；同时，由于MgO-C质水口耐火材料被侵蚀，MgO在絮流区与Al2O3碰撞生成MgO·Al2O3，铁液滴在夹杂物孔隙中凝固黏结，使堵塞物进一步长大，将水口完全堵塞。因此，可以通过优化喂线操作、控制钢中的钙铝比位于0.127～0.225、改进水口材质等措施来预防水口堵塞。

Analysis on nozzle clogging of 49MnVS steel during production

Non-quenched and tempered steel contains high aluminum and sulfur， which often causes the nozzle clogging during continuous casting and hampers the production. In order to explore the cause of the nozzle clogging of non-quenched and tempered steel， and propose preventive measures， the X-ray fluorescence， the X-ray diffraction and the thermodynamic calculation were used to analyze the clogs of the nozzle of 49MnVS. The results showed that those blockages were mainly CaO?6Al2O3， CaO?Al2O3， MgO?Al2O3 and Fe. The calcium yield in the production was only 53.33% of the goal. The thermodynamic calculation indicated that the low ratio of calcium and aluminum caused the nozzle clogging and formed a large amount CaO?6Al2O3 and CaO?Al2O3 inclusions with a high melting point， which adhered and aggregated at the nozzle. At the same time， the erosion of the MgO-C nozzle leaded to the collision of MgO and Al2O3 and formed MgO?Al2O3 in turbulent flow zones. The solidification and adhesion of iron droplets in the pore of inclusions caused the growth of blockages and completely blocked the nozzle. Therefore， it is possible to prevent the nozzle clogging by optimizing the feeding operation， controlling the ratio of calcium and aluminum in the range of 0.127 to 0.225 and improving the materials of nozzle.