炼钢 ›› 2019, Vol. 35 ›› Issue (6): 60-66.

• 产品工艺与质量控制 • 上一篇    下一篇

“BOF→LF→RH→钙处理→CC”工艺生产管线钢过程夹杂物演变

程 林1,杨 文2,李树森1,任 英2,张立峰2   

  1. (1. 首钢股份有限公司 首钢智新迁安电磁材料有限公司,河北 唐山 064404; 2. 北京科技大学 冶金与生态工程学院,北京 100083)
  • 接受日期:1900-01-01 出版日期:2019-12-05

Evolution of Inclusions in Pipeline Steel Producted by the Route of BOF-LF-RH-Ca Treatment-CC

  • Accepted:1900-01-01 Online:2019-12-05

摘要: 对“BOF→LF→RH→钙处理→CC”工艺生产X70管线钢过程的夹杂物行为演变进行了研究。发现LF精炼过程夹杂物由多面体Al2O3转变为球形的MgO-Al2O3-CaO-CaS复合夹杂。RH精炼过程夹杂物成分变化不大,但是夹杂物数量和尺寸都减小。钙处理后,夹杂物中的CaO和CaS含量增加,w(CaO)/w(Al2O3)增大,平均成分偏离低熔点区。在连铸过程由于二次氧化导致钢中Als和T.Ca含量降低,同时中间包夹杂物中CaO和CaS含量有所降低,夹杂物数密度和最大尺寸都有所增加,应加强浇铸过程的保护浇铸,以更好地保证钙处理效果。由于降温过程钢-夹杂物之间平衡的移动,夹杂物由中间包中液态的CaO-Al2O3转变为铸坯中的以Al2O3-CaS和MgO-Al2O3类型为主的高熔点夹杂物。

关键词: 管线钢, 钙处理, 夹杂物转变, 二次氧化

Abstract: The evolution of inclusions in the pipeline steel producted by the route of “BOF→LF→RH→Ca treatment→CC” was investigated. It was found that the polyhedral Al2O3 changed to spherical MgO-Al2O3-CaO-CaS complex inclusions after LF refining. There was no obvious change on the composition of inclusions, on the contrary, both the number density and the size of inclusions decreased during the RH refining process. After Ca treatment, the contents of CaO and CaS in inclusions increased, induced the increase of CaO/Al2O3, and the moving out from the low melting point zone of inclusions. During the continuous casting, the contents of Als and T.Ca in steel decreased due to the reoxidation, leading to the decrease of CaO and CaS in inclusions and the increase of the number density and maximum size of inclusions. Thus, protective casting should be strengthened to ensure the effect of calcium treatment. Due to the equilibrium movement between steel and inclusions during the cooling process, inclusions changed from liquid CaO-Al2O3 in tundish to high-melting-point inclusions in slab, which were mainly of Al2O3-CaS and MgO-Al2O3 types.

Key words: pipeline steel, Ca-treatment, inclusion transformation, reoxidation