Deoxidation mechanism in low arbon steel killed with aluminium

摘要

Samples were taken from unkilled low carbon liquid steel using a sampling device, which contained different amounts of metallic aluminium, The aluminium doxidises the liquid steel, resulting in small and mainly spherical inclusions of galaxite/hercynite and various alumina phases. Based on scanning electron microscopy observations, chemical analyses and powder X-ray diffraction, we propose that during the deoxidation process the galaxite/hercynite particles reat to gamma-Al_2O_3, by exchanging manganese or iron in the spinel structure with aluninium from the steel melt. The instability of gamma-Al_2O_3 causes the subsequent transformation to other metastable alumina phases.