LF-VD精炼过程中GCr15钢中夹杂物的行为

Analysis on Behavior of Inclusions of GCr15 in Refining Process of LF-VD

对GCr15在精炼过程产生的夹杂物进行分析,为减少夹杂、提升钢材质量奠定理论基础。采用金相、电子探针、光谱等方法,取样分析了西宁特钢EAF-LF-VD-CC流程冶炼的GCr15在LF-VD精炼时非金属夹杂物数量和尺寸的变化,并确定了各工位的夹杂类型和形成原因。试验结果表明,精炼过程夹杂总量一直呈下降趋势。LF精炼后,各尺寸夹杂数量明显变少,主要为尺寸较大的钙铝酸盐和含铝镁钙的复合夹杂;VD脱气后,粒径大于20μm的夹杂完全上浮去除,残余夹杂主要为粒径小于10μm的钙铝酸盐和硅铝酸盐。根据分析结果,应优化冶炼工艺,增大对小尺寸夹杂物的去除率,同时应控制Ti、N的含量,避免TiN夹杂在钢液凝固过程中的析出和聚集。

It can provide theoretical basis for inclusion reduction and quality promotion through investigating the be havior of GCrl5 inclusions in refining process. Changes in value and size for non-metallic inclusions of GCrl5 in LF-VD refining were analyzed and the types and formation reason of inclusions in all stages were discussed for the process of EAF-LF-VD-CC in Xining Special Steel by the methods of metallo-graphy, electron probe and spectrographic analysis. The results show that the number of inclusions is less and less in the refining process. After the LF refining, all inclusions become less apparently and are mainly CaO-Al2O3 and CaO-Al2O3-MgO that have bigger sizes. At the end of VD, the inclusions which are greater than 20μm have been eliminated completely; the remaining inclusions are mainly CaO-Al2O3 and SiO2-Al2O3 that are less than 10μm. According to the analysis result, the smelting process should be optimized in order to increase the removal ratio of small size inclusions. At the same time,titanium and nitrogen content should be controlled to avoid the precipitation and agglomeration of TiN inclusions during solidification process.