Prediction of Oxide Phases Formed upon Internal Oxidation of Advanced High-Strength Steels

Abstract

The effect of Cr on the oxidation of Fe-Mn-based steels during isothermal annealing at different dew points was investigated. The Fe-Mn-Cr-(Si) phase diagrams for oxidizing environments were computed to predict the oxide phases. Various Fe-Mn steels with different concentrations of Cr and Si were annealed at 950°C in a gas mixture of Ar or N 2 with 5 vol% H 2 and dew points ranging from -45 to 10°C. The identified oxide species after annealing match with those predicted based on the phase diagrams. (Mn,Fe)O is the only oxide phase formed during annealing of Fe-Mn binary steel alloys. Adding Cr leads to the formation of (Mn,Cr,Fe) 3 O 4 spinel. The dissociation oxygen partial pressure of (Mn,Cr,Fe) 3 O 4 in the Fe-Mn-Cr steels is lower than that of (Mn,Fe)O. The Si in the steels results in the formation (Mn,Fe) 2 SiO 4 , and increasing the Si concentration suppresses the formation of (Mn,Cr,Fe) 3 O 4 and (Mn,Fe)O during annealing.

Surface Oxidation and Wettability of Fe–Mn and Fe–Mn–Si-Alloyed Steel After Annealing

“…Our previous studies [25,26] already showed that the oxides formed at the steel surface during annealing at high temperatures in relatively low oxygen partial pressure environments can be well predicted by thermodynamic calculations, as was validated by X-ray diffractometry (XRD). Apparently, local equilibrium exists between the steel surface and the annealing gas at high temperatures.…”

“…[21][22][23] The transition from internal to external oxidation of Fe-Mn alloyed steels have been studied [24] and it was observed that increasing the annealing dew point promotes internal oxidation. The oxides phases formed on Fe-Mn-Cr alloyed steels also have been studied with simulations and experiments [25,26] and showed that adding Cr to the Fe-Mn-based steel alloys results in the formation of (Mn,Cr,Fe) 3 O 4 spinel during annealing. Increasing the Mn concentration in the alloy promotes the formation of (Mn,Cr,Fe) 3 O 4 spinel and (Fe,Mn)O.…”

Anticoking Performance of Electrodeposited Mn/MnO Surface Coating on Fe–Ni–Cr Alloy during Steam Cracking

“…The EDS compositions after analyzing several different points on the Mn-Inc sample are summarized in SI Table S2, and the small amounts of Fe on the Mn-Inc surface varied significantly (1.5 ± 1.4 wt %). It is thermodynamically possible that the Fe species may have formed some mixed oxides of Mn and Fe (i.e., (Mn,Fe)O or Mn x Fe 3‑x O 4 spinel phases), − but none of these were conclusively detected via XRD (Figure ), likely because the total Fe content was quite low. After the third coking cycle, the 2 theta positions of the MnO peaks slightly increased by 0.1–0.2°.…”

On the competition between synchronous oxidation and preferential oxidation in Cu-Zr-Al metallic glasses

“…Oxidation occurs inevitably during the service of such micro/nano-sized alloy components, thereby affecting their surface properties [15][16][17][18][19]. Controlled pre-oxidation treatments of the fabricated alloys can be performed to tune and stabilize surface-related properties in an efficient and economical way [20,21]. The oxidation of crystalline ternary metallic alloys has been studied intensively in the past decades.…”