Effect of Cobalt on the Microstructure and Corrosion Behavior of Martensitic Age-Hardened Stainless Steel

Journal Article · Mon Jul 15 04:00:00 EDT 2019 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/S11665-019-04185-X· OSTI ID:22970645

Zhang, Wei ^[1]; Zhang, Xin ^[2]; Qiao, Guanjun ^[1]; Zou, Dening; Zhou, Yuqing; Shen, Chu ^[2]

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1. Xi’an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials (China)
2. Xi’an University of Architecture and Technology, School of Metallurgy and Engineering (China)

To evaluate the influence of cobalt on the microstructure and pitting behavior of martensitic age-hardened stainless steel (MASS), the microstructures and electrochemical behaviors were characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, potentiodynamic curve, electrochemical impedance spectroscopy, and Mott–Schottky analysis. Results indicated that adding cobalt reduced the grain size of the original austenite, refined the lath martensite, inhibited the precipitation of Cu-rich phases, and increased the content of reversed austenite. Compared with the cobalt-free steel, the cobalt-containing steel has a higher pitting potential, lower corrosion current density, and higher pitting resistance. The primary components of the passive film grown on the cobalt-free steel included (Cr, Fe) oxides, such as Cr{sub 2}O{sub 3}, Cr(OH){sub 3}, FeOOH, and Fe{sub 2}O{sub 3}. The cobalt-containing steel included the aforementioned components as well as Co, which was attributed to the formation of the passive film in the forms of CoFe{sub 2}O{sub 4}, Co(OH){sub 2}, and CoO. In addition, the synergy of the refined lath martensite and the precipitation of the Cu-rich phase induced an increase in corrosion resistance in MASS containing cobalt.

• OSTI ID: 22970645
• Journal Information: Journal of Materials Engineering and Performance, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 7 Vol. 28; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBON MONOXIDE
CHROMATES
CHROMIUM OXIDES
COBALT HYDROXIDES
COBALT OXIDES
CORROSION RESISTANCE
ELECTROCHEMISTRY
FERRITES
GRAIN SIZE
IRON OXIDES
MARTENSITE
MARTENSITIC STEELS
OPTICAL MICROSCOPY
OXIDATION
PITTING CORROSION
SCANNING ELECTRON MICROSCOPY
STAINLESS STEELS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY PHOTOELECTRON SPECTROSCOPY