高品质含钛焊丝钢生产过程中夹杂物的行为演变

采用扫描电镜观察了含钛焊丝钢中夹杂物的形貌与组成,重点分析了冶炼过程中夹杂物的形成和演变规律。结果表明,LF进站前的夹杂物主要类型为球形的SiO₂-Al₂O₃复合夹杂物,其尺寸在6 μm左右;在LF精炼中,SiO₂-Al₂O₃型夹杂物转变为不规则椭球形SiO₂-Al₂O₃-CaO型夹杂物,其尺寸为5～10 μm。且随着精炼的进行,夹杂物的数量密度由LF进站前的131.81变成最终出站时的42.84个/mm2。在钢水精炼期间,夹杂物成分由最初的w(Al₂O₃)＜20%的区域向CaO含量升高的区域移动,Al₂O₃的质量分数为20%～35%;LF精炼结束后的夹杂物类型除了SiO₂-Al₂O₃-CaO外,还存在较多的近球形SiO₂-Al₂O₃-CaO-MgO与形状不规则的SiO₂-Al₂O₃-CaO-MgO-TiO_x系夹杂物。另外,在铸坯中的复合氧化夹杂物的外层还发现有TiN夹杂物析出。夹杂物成分最终在铸坯中停留在w(Al₂O₃)＜25%的区域,数量密度降低到27个/mm2左右。

Evolution behavior of inclusions during production of high-quality titanium-bearing welding wire steel

The morphology and composition of inclusions in titanium-bearing wire steel were observed by scanning electron microscopy, and the formation and evolution of inclusions during smelting were particularly analyzed. The results showed that the typical inclusions before LF treatment were spherical SiO₂-Al₂O₃ composite inclusions, the size of which was about 6 μm. In the LF refining process, the SiO₂-Al₂O₃ type inclusions were transformed into irregular ellipsoidal SiO₂-Al₂O₃-CaO inclusions with a size of 5-10 μm. And as the refining progresses, the number density of inclusions decreased from 131.81 before the LF treatment to 42.84/mm2 at the end of LF treatment. During the molten steel refining, the inclusion composition moved were transferred from the initial w(Al₂O₃)<20% region to the region where the CaO content increased, and the mass fraction of Al₂O₃ was 20% to 35%. In addition to the SiO₂-Al₂O₃-CaO inclusion, there were many near-spherical SiO₂-Al₂O₃-CaO-MgO and irregularly SiO₂-Al₂O₃-CaO-MgO-TiO_x inclusions after LF refining. Also, the precipitation of TiN inclusions occurred in the outer layer of the composite oxide inclusion in the slab. The inclusion component eventually stayed in the area of w(Al₂O₃)<25% in the slab, and the number density decreased to about 27/mm2.