Selective Oxidation in Press Hardening Steel during Annealing with Different Dew Points

摘要

The selective oxidation of the 22MnB5 press hardening steel during recrystallization with different dew points in the H_2-N_2 annealing atmosphere has been investigated in a hot dip process simulator (HDPS), X-ray photo-electron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis revealed differences in oxidation. It was found that less oxide nodules formed at highest dew points which indicated the transition of external oxidation to internal oxidation. Furthermore, remarkable BN was found on the external surface during annealing under lowest dew point, which suppress the formation of oxidation film. As researched in this paper, the wettability of the external surface is not be deteriorated under highest and lowest dew points.