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采用铁水脱硫-转炉-LF炉-RH-钙处理-连铸工艺路线,出钢采用Al脱氧,造高碱度低氧化性精炼渣,生产X80管线钢。研究了精炼过程中夹杂物的成分、尺寸、形貌和数量等变化情况,确定了钢中夹杂物在不同精炼环节的变化规律,探讨了夹杂物中MgO和CaO的来源。结果表明,采用该冶炼工艺路线所生产的管线钢总氧的质量分数在10×10-6~12×10-6,钢中20μm以下夹杂物所占比例达到了90%,钢水具有很高的洁净度水平。在精炼过程中夹杂物MgO质量分数逐渐降低、CaO质量分数逐渐增加,精炼结束后钢中夹杂物为球形MgO-Al2O3-CaO类夹杂物,MgO、Al2O3和CaO质量分数平均分别2.6%、53.7%和43.7%,该类夹杂物外层为CaS,在精炼钢水温度下为液态,表明钢中夹杂物得到了有效的变性处理。在钢中夹杂物去除效果方面,软吹氩工艺对于10μm以下夹杂物的去除效果最好,去除率达到了81%。
Using hot metal desulphurization - converter - LF furnace - RH-calcium treatment - continuous casting process line, tapping Al deoxidation, high alkalinity low oxidation refining slag, the production of X80 pipeline steel. The composition, size, morphology and amount of inclusions in the refining process were studied. The variation of inclusions in steel was determined at different refining stages, and the sources of MgO and CaO in inclusions were discussed. The results show that the mass fraction of total oxygen in pipeline steel produced by the smelting route is in the range of 10 × 10-6 ~ 12 × 10-6, and the proportion of inclusions below 20μm in steel reaches 90%. The molten steel has high Cleanliness level. In the process of refining, the mass fraction of inclusions MgO gradually decreased and the mass fraction of CaO gradually increased. The inclusions in the steel were spherical MgO-Al2O3-CaO inclusions after refining. The average mass fractions of MgO, Al2O3 and CaO were 2.6% and 53.7% And 43.7% respectively. The inclusions of these inclusions are CaS, which is liquid at the temperature of molten steel, indicating that the inclusions in steel have been effectively denatured. In the removal of inclusions in steel, soft argon blowing process for the removal of inclusions below 10μm the best removal efficiency reached 81%.