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

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 54; no. 1; pp. 97 - 105
• Main Authors: You, Yuliu, Kim, Jungki, Kwakernaak, Cees, Brouwer, Johannes C., Westerwaal, Ruud, Sloof, Willem G.
• Format: Journal Article
• Language: English
• Published: New York Springer US 2023; Springer Nature B.V
• Subjects: Alloy steels; Annealing; Characterization and Evaluation of Materials; Chemistry and Materials Science; Contact angle; Dew point; Grain boundaries; Image analysis; Iron; Manganese steels; Materials Science; Metallic Materials; Morphology; Nanotechnology; Original Research Article; Oxidation; Oxides; Photoelectrons; Scanning electron microscopy; Silicon dioxide; Spectrum analysis; Steel alloys; Structural Materials; Surfaces and Interfaces; Thin Films; Wettability; Wetting; X ray photoelectron spectroscopy
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-022-06847-3

The surface oxidation and wettability of Mn and Si-alloyed steel after annealing at different conditions are studied with scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and a so-called de-wetting method. After exposure at 950 °C for 1 hour in an Ar + 5 vol pct H
2
gas atmosphere with dew points (DP) ranging from – 40 °C to 10 °C, oxides were observed along the grain boundaries or dispersed on the surface for the Fe–1.8 Mn steels while a continuous oxides layer was formed on Fe–1.9 Mn–0.94 Si steels (composition in weight fractions). The oxides formed at different DPs were predicted based on thermodynamic calculations. (Fe,Mn)O was formed on Fe–1.8 Mn steel at the whole range of DPs, while the oxide phase on Fe–1.9 Mn–0.94 Si steel depends on the DP. At low-DP SiO
2
were formed and with increasing the DP (Fe,Mn)SiO
3
or (Fe,Mn)SiO
3
 + (Fe,Mn)
2
SiO
4
were formed and finally (Fe,Mn)
2
SiO
4
were formed. An increase of the fraction of Fe in the oxide with increasing DP for both steels was observed with XPS analysis. As a measure for the surface wettability, the contact angle of Pb droplets on the annealed steels surfaces was determined with SEM and image analysis software. Also, the contact angle of Pb on pure Fe and on the Mn and Si alloyed steels free of surface oxides was measured for comparison. The results show that the contact angle of Pb on the steel surfaces after annealing decreases with increasing DP. This improved wettability with increasing dew point is related to the Fe fraction of the oxides formed on the surface.