中文摘要：

针对Q235B板坯连铸过程中出现的铸坯质量问题,检测了现场保护渣的物化性能,并结合现场铸坯质量情况,对渣膜的矿相结构进行了系统研究。结果发现该钢种保护渣的熔化温度和黏度较中碳包晶钢的理论值偏低,正常渣膜与事故渣膜的矿相结构也存在较大差异;正常渣膜中结晶率均达到90%以上,结晶矿物主要为黄长石、枪晶石和硅灰石;而板坯出现纵裂对应的事故渣膜的突出特点是,结晶率下降至65%~70%;出现粘结漏钢事故的渣膜中,虽然结晶率达到90%以上,但有枪晶石晶体大量析出。进一步结合Q235B板坯连铸工艺和保护渣的化学成分,分析了渣膜结构异常及板坯表面质量缺陷产生的原因。

英文摘要：

In light of the slab quality problems in the production of Q235B steel,the chemicophysics properties of the mold powder were analyzed;and then combining the quality of slabs,the microstructures of slag films were roundly studied.The results showed that,the melting temperature,viscosity of this flux was lower than the theoretical value of fluxes casting for peritectic steel,and the microstructures were different between reasonable films and unqualified films.The mineralogical phase of reasonable films for Q235B steel slab casting,of which crystal rate could reach 90%,include akermanite,cuspidine and wollastonite.The outstanding characteristic of unqualified films with longitudinal cracks accidents was that crystal rate could be only 65%-70%.As to unqualified films with sticking breakout accidents,the biggest difference comparing with reasonable films was the mass formation of cuspidine,while crystal rate could anomaly reach 95% or more.Combining the parameters of casting technics and chemical components of the mold powder casting for Q235B steel,the causes of abnormal film structures and quality defects of slab surface were finally given.