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采用扫描电镜和大样电解等检验方法对抗硫管线钢的冶炼过程试样和连铸坯中夹杂物的数量、尺寸、成分、形貌进行系统分析。结果表明:钢液经过LF精炼后,显微夹杂物的面积比降低了34.7%;中间包钢液的夹杂物面积比较VD出站增加了6.1%。LF进站钢液中的夹杂物主要为Al_2O_3夹杂物,在LF精炼和VD真空处理过程中由于钢渣间的相互作用,形成以CaO、MgO、Al_2O_3为主要组成的复合型夹杂物。钙处理后夹杂物中的CaO和Al_2O_3的物质的量比接近12∶7,并与钢液发生了脱硫反应,形成了含CaS的复合夹杂物。中间包开浇阶段铸坯中的显微夹杂物和大型夹杂物都明显高于稳定浇铸状态;在稳定浇铸状态下,铸坯中的w(T[O])小于15×10~(-6),大型夹杂物的含量小于0.2 mg/kg;大型夹杂物的主要来源是钢包引流砂、结晶器保护渣。
The number, size, composition and morphology of the inclusions in the smelting process sample and the slab against sulfur pipeline steel were systematically analyzed by scanning electron microscopy and large sample electrolysis. The results show that the LF refining reduces the area ratio of micro-inclusions by 34.7%. The inclusion area of the molten steel in the tundish increases by 6.1% compared with that of VD. The inclusions in LF liquid steel are mainly Al 2 O 3 inclusions. Due to the interaction between steel slag during LF refining and VD vacuum treatment, composite inclusions mainly composed of CaO, MgO and Al 2 O 3 are formed. The content of CaO and Al_2O_3 in the inclusions after calcium treatment is close to 12: 7, and desulphurization reaction with molten steel occurs, forming composite inclusions containing CaS. The microscopic inclusions and large inclusions in casting billet at casting stage were significantly higher than those in steady casting. Under stable casting conditions, the w (T [O]) in the billet was less than 15 × 10 -6 ), The content of large inclusions is less than 0.2 mg / kg; the main sources of large inclusions are ladle drainage sand and mold flux.