One of the quality criteria for Interstitial Fee (IF) steels is the metal purity with respect to non-metallic inclusions (NMI), which are harmful for the plastic properties of the material. Furthermore, they cause a formation of surface defects in flat rolled products and reduce the rate of steel casting due to nozzle clogging. This article presents the results of a study of the content, composition, size and morphology of non-metallic inclusions and clusters in steel samples taken during ladle treatment, casting as well as from slabs and steel sheets after rolling of IF steel. The characteristics of NMI and clusters were determined by using conventional two-dimensional quantitative metallographic investigations of polished sections of steel samples (2D method), electrolytic extraction (EE method) of samples followed by investigations of inclusions and clusters by using scanning electron microscopy and energy dispersive spectroscopy and fractional gas analysis (FGA method). By using EE method, different types of inclusions and clusters, their formation, growth and behavior during different stages of IF steel production were studied. The results obtained by the EE method agreed well with the results of the quantitative determination of oxide NMI by using the FGA method. The method of fractional gas analysis shows the dynamics of changes in the content of various types of oxide non-metallic inclusions during ladle treatment and casting of steel. The obtained results can be used to analyze the causes of the formation of harmful NMI in the metal and to optimize ladle treatment of IF steel grades.

填隙费（IF）钢的质量标准之一是相对于非金属夹杂物（NMI）的金属纯度，这会危害材料的塑性。此外，它们导致扁平轧制产品中表面缺陷的形成，并由于喷嘴堵塞而降低铸钢速度。本文介绍了对钢包处理，铸造以及IF钢轧制后的板坯和钢板中非金属夹杂物和团簇的含量，成分，尺寸和形貌进行研究的结果。NMI和团簇的特征是通过使用常规二维定量金相研究方法对钢样品的抛光部分（二维方法）进行测定的，样品的电解萃取（EE方法），然后使用扫描电子显微镜和能量色散光谱法和分馏气体分析（FGA方法）研究夹杂物和团簇。采用EE法研究了中频钢生产过程中不同类型的夹杂物和团簇及其形成，生长和行为。EE法获得的结果与FGA法定量测定氧化物NMI的结果非常吻合。分馏气体分析方法显示了钢水包处理和铸钢过程中各种类型的氧化物非金属夹杂物含量变化的动态。获得的结果可用于分析金属中有害NMI的形成原因，并优化IF钢牌号的钢包处理。