2022 Volume 108 Issue 10 Pages 728-738
A selective oxidation of alloying elements such as Si and Mn is generally important for the zinc wettability of high strength steels in the process of hot dip galvanizing. In the present paper, the effect of both the temperature and the dew point of recrystallization annealing process on the selective surface oxidation behavior of 2 mass% Mn added steel were investigated by glow discharged spectroscopy (GD-OES), secondary electron microscopy (SEM) and transmission electron microscopy (TEM). When the annealing temperature was below 973 K, the Mn internal oxidation did not occur and the amount of Mn external oxidation increased with increasing temperature regardless of the dew point. On the other hand, when the annealing temperature was more than 1023 K, both the external oxidation and the internal oxidation were observed. Especially, the internal oxidation occurred actively and the external oxidation is suppressed when the dew point is more than 263 K. Wagner’s theory could explain the phenomenon which the internal oxidation was occurred in the wider range of dew point as the annealing temperature increased.
