高强汽车大梁钢铸坯中大型非金属夹杂物研究

ANALYSIS OF LARGE NONMETALLIC INCLUSIONS IN HIGH STRENGTH AUTOMOBILE GIRDER STEEL CASTING SLAB

为研究高强汽车大梁钢铸坯中大型非金属夹杂物的含量、大小、形貌及类型,采用大样电解结合扫描电镜和能谱仪对700L钢中的大型夹杂物进行分析。结果表明:试验钢铸坯宽面1/4处的夹杂物含量高于宽面1/2处的;内弧侧夹杂物含量高于外弧的,采用双联工艺,能更好地去除钢中的大型夹杂物。夹杂物主要是大于80μm的不规则块状硅铝酸盐系和小于80μm的球状铝钙系。硅铝酸盐系夹杂物主要由脱氧产物、钢包耐材和卷入的结晶器保护渣相互复合而成;铝钙系夹杂物主要是由于精炼卷渣而形成的。工艺改进后,转炉终点钢水O含量降低,结晶器液面波动控制稳定,单联工艺下内弧1/4处夹杂物数量明显减少,达到了双联工艺对夹杂物的控制水平。

To investigate the content,size,morphology and types of large non-metallic inclusions in high-strength automotive beam steel casting slabs,large-scale electrolysis combined with scanning electron microscopy and energy dispersive spectroscopy was used to analyze the large inclusions in 70OL steel.The results indicate that the content of inclusions at 1/4 of the wide surface of the test slab is higher than that at 1/2 of the wide surface;the content of inclusions on the inner arc side is higher than that on the outer arc.Adopting a dual process can better remove large inclusions in the steel.The inclusions mainly consist of irregular block shaped aluminosilicate systems larger than 80μm and spherical aluminum calcium systems smaller than 80μm.Aluminum silicate inclusions are mainly composed of deoxidation products,ladle refractory materials and protective slag rolled in crystallizer,aluminum-calcium inclusions are mainly formed by refining slag.After the process improvement,the O content in the final molten steel of the converter decreased,and the fluctuation control of the crystallizer liquid level was stable.The number of inclusions at 1/4 of the inner arc was significantly reduced under the single link process,reaching the control level of inclusions in the double link process.