Influence of Si Addition on Reduction Behavior of Fe Oxide on Mn-Added Steel Sheet

Abstract

The influence of the Si content of Mn-added steel sheets on the reduction behavior of Fe oxide during oxidation followed by annealing in a 10% H₂ atmosphere simulating the Fe oxidation-reduction process was investigated using 5.2 mass% Mn steel with 0, 0.2 and 0.5 mass% added Si. Reduction of the Fe oxide was more rapid in the 0.2% and 0.5% mass% Si steels than in the 0 mass% Si steel. Because Si addition increased the proportion of hematite (Fe₂O₃) and decreased that of wustite (FeO) in the Fe oxide, the difference in reduction speed due to Si addition is thought to depend on the composition of the Fe oxide. It was suggested that reduction from hematite to magnetite (Fe₃O₄) induces larger lattice defects in the Fe oxide, resulting in a higher diffusion rate of O.