Chemical State Analysis of Inclusions in IF Steel by EPMA and Auger Electron Spectroscopy

Abstract

Chemical state of inclusions in IF steel was studied by EPMA and Auger electron spectroscopy (AES). The chemical state of Al and Ti was mostly Al₂O₃ and TiN, respectively. X-ray images of Al₂O₃ inclusions in IF steel (as cast) appearing on the mechanically polished sample surface were taken by EPMA. The inclusions could be classified into two types. One is a small inclusion (1 μm) having a small Al₂O₃ core completely covered with TiN, and the other is a large one which consists mostly of Al₂O₃ and is partially covered with TiN. To estimate the state of inclusions in a bulk sample quickly, sample was melted by electron beam and floated inclusions (raft) were analyzed (EB method). Floated inclusions of IF steel were Al₂O₃ and those containing Ti inclusions were rarely found. Observed inclusions containing Ti showed very vague X-ray images and some of them showed a melted appearance. Care must be taken to examine the state of inclusions in IF steel by EB method.