电渣重熔过程结晶器旋转对钢中夹杂物的影响

基于自行设计的双极串联结晶器旋转电渣重熔炉，采用ASPEX全自动夹杂物分析仪研究了结晶器转速对M2电渣锭洁净度的影响。结果表明，不论结晶器是否旋转，电渣锭中的夹杂物组成基本不变，主要由Al2O3, Al2O3–MnS, Al2O3–SiO2–CaO–MnS, MgO–Al2O3–SiO2–CaO–MnO, MgO–Al2O3–SiO2–CaO–TiO2–MnS, Al2O3–SiO2–CaO–MnO–TiO2组成，其中以Al2O3, Al2O3–SiO2–CaO–MnO–TiO2和Al2O3–MnS数量最多。结晶器静止电渣重熔时，钢中的夹杂物数量较多，且存在50 ?m以上的大颗粒夹杂物，而结晶器转速为6和13 r/min时，夹杂物数量减少，大颗粒夹杂含量大大降低；转速增至19 r/min时，夹杂物数量及尺寸又进一步增加，同时钢中全氧含量、氮含量明显增加。电渣锭中大颗粒夹杂物得以去除的主要原因是结晶器旋转导致金属自耗电极末端的熔融层变薄、熔滴尺寸变小，渣–金接触面积增大，促进了夹杂物被熔渣去除；过快的转速会增加自耗电极氧化、减少渣–金接触时间，从而降低电渣重熔过程的精炼能力。

Effect of mould rotation on inclusions in ESR ingot

Based on the self-designed bifilar electroslag remelting furnace with mould rotation, the effect of mould rotation speed on cleanliness of electroslag ingot for M2 high speed tool steel was studied in detail by ASPEX automatic inclusion analyzer. It was found that the inclusions in the ESR (Electroslag Remelting) ingot were mainly composed of Al2O3, Al2O3–MnS, Al2O3–SiO2–CaO–MnS, MgO–Al2O3–SiO2–CaO–MnO, MgO–Al2O3–SiO2–CaO–TiO2–MnS and Al2O3–SiO2–CaO–MnO–TiO2. Among them, Al2O3, Al2O3–SiO2–CaO–MnO–TiO2 and Al2O3–MnS accounted for the largest proportion. During ESR with the stationary mould, there were more inclusions in steel and the diameter of the largest inclusion exceeded 50 μm. When the mould rotation speed was 6 and 13 r/min respectively, the number of inclusions, especially large inclusions, were greatly reduced. However, when the mould rotation speed increased to 19 r/min, the number and size of inclusions increased further, and the total oxygen and nitrogen content in the steel increased too. The main reason for the removal of large inclusions in ESR ingots was that the melting layer at the end of metal consumable electrode became thinner and the size of droplets became smaller due to the rotation of mould, and the contact area between slag and molten metal increased, which promoted the removal of inclusions. However, the excessive mould rotation increased the oxidation of consumable electrode and reduced the contact time between slag and molten metal, thus reducing the refining capacity of the ESR process.