连铸保护渣对20Mn23AlV铸坯表面微裂纹的影响

 针对太钢采用连铸工艺并使用低碱度保护渣生产高锰钢20Mn23AlV铸坯表面存在的微裂纹问题，通过现场取样、渣-金反应等试验，结合金相显微镜、扫描电镜和能谱分析等手段系统研究了表面裂纹的特征和形成过程，在此基础上研究了现有低碱度保护渣在使用前后的成分变化、熔点、黏度和传热等指标的变化情况。结果表明，生产过程中低碱度保护渣中的SiO2被钢液中的铝还原，导致液态渣成分发生变化，从而影响了坯壳与结晶器铜板之间的润滑和传热等性能，导致了高锰钢20Mn23AlV铸坯表面微裂纹缺陷。连铸生产钢液中含有强还原性元素（铝）时，应采用低SiO2质量分数的连铸保护渣，以减少高锰钢连铸坯表面微裂纹的产生，提高铸坯表面质量，实现高锰钢连铸生产顺行。

Effect of mold fluxes on slab surface crack for 20Mn23AlV

In present work,the continuous casting(CC)production of high manganese steel 20Mn23AlV in the TISCO and the slab surface cracks of the 20Mn23AlV were investigated. By means of industrial samples and the slag-metal reac-tion experiment,the characteristics and forming process of slab surface crack were systematically studied through the me-tallographic microscope,the scanning electron microscopy and the energy spectrum analysis. While the variation of in-dexes such as the chemical compositions before and after mold fluxes were used,melting point,viscosity,heat transfer and so on were studied. The results showed that the SiO2 in mold fluxes was deoxidized by the Al in the molten steel, leading to changes of the mold fluxes composition during the continuous casting process,and properties of the lubrica-tion and the heat transfer for mold fluxes also changed,which could increase slab surface cracks of high manganese steel 20Mn23AlV. Therefore,during CC production of the steel with strong reducibility element(Al),low SiO2 content mold fluxes should be used in order to reduce slab surface cracks,improve the surface quality of slab and ensure CC produc-tion of high manganese steel smoothly.