Influence of Mn, Si and Al on the selective oxidation behavior of low carbon steel

Abstract

The selective oxidation phenomenon is inevitable during the continuous annealing of advanced high strength steel (AHSS) under the low oxygen partial pressure (POxy) atmosphere. The external and internal oxides can deteriorate the wettability and result in forming defects on the strip surface after hot dip galvanizing (HDG) process. The oxidation behavior was investigated by many researchers in teams of the morphology of surface oxides and annealing conditions for transition between external and internal oxidation. In addition the numerical modes for internal oxidation behavior were proposed by many authors. However, the models are not yet applied in the field due to lack of the reliability. The present study focuses on selective oxidation behavior in the steels containing single oxidant, double oxidants and triple oxidants to analyze fundamental effects of alloying elements. With cross sectional STEM observation, the morphology and oxidation behavior are investigated and comparison calculation depth to measured depth is carried out. The proper criteria for internal oxidation depth is proposed in the research, and new prediction model is suggested describing intra-oxidation depths and grain boundary oxidation depths in similar with measured values.