Fe-24 wt.%Cr-4.1 wt.%C hardfacing alloy: Microstructure and carbide refinement mechanisms with ceria additive

Journal Article · Mon Oct 15 04:00:00 EDT 2012 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2012.07.004· OSTI ID:22163136

Zhou, Y. F.; Yang, Y. L.; Jiang, Y. W.; Yang, J. ^[1]; Ren, X. J. ^[2]

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1. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)
2. School of Engineering, Liverpool John Moores University, Liverpool L3 3AF (United Kingdom)

The microstructure and carbide refinement mechanisms of Fe-24 wt.%Cr-4.1 wt.%C hardfacing alloys with 0 wt.%, 0.5 wt.%, 1.0 wt.%, 2 wt.%, and 4 wt.% ceria additives have been systematically investigated in this work. Optical microscopy, field emission scanning electron microscopy with energy dispersive spectrometer, and X-ray diffraction were collectively used to study the microstructure, the phase components, and the chemical formation of inclusion formed in the welding process. Wear-resistance of the alloys was comparatively studied using an abrasive wear testing machine. The structure analysis results show that the Fe-Cr-C hardfacing alloy mainly consists of martensite, retained austenite, MC carbide and M{sub 7}C{sub 3} carbide. With increasing ceria additive contents, the average size of the primary M{sub 7}C{sub 3} carbide decreases and reaches a most refined state in the alloy with 2 wt.% ceria additives. Comparative wear tests data shows that the wear resistance of the hardfacing alloys with ceria additives is better than that without ceria additive. In a good agreement with the carbide refinement results, the wear resistance of the alloy reaches an optimum level in the sample with 2 wt.% ceria additive. The main RE inclusion type identified with in-situ XRD analysis is RE inclusion Ce{sub 2}O{sub 2}S. Thermodynamics calculation confirms that this type of RE inclusion could precipitate prior to M{sub 7}C{sub 3} carbides, and act as a heterogeneous nucleus for M{sub 7}C{sub 3} in the welding process, which effectively provides a mechanism for significant refinement of the M{sub 7}C{sub 3} carbide and improves its wear resistance. - Graphical Abstract: Rare Earth inclusion (Ce{sub 2}O{sub 2}S) distributes in the primary M{sub 7}C{sub 3} carbide. Moreover, Ce{sub 2}O{sub 2}S, which acts as heterogeneous nuclei of the primary M{sub 7}C{sub 3} carbide, is medium effective. Therefore, the primary M{sub 7}C{sub 3} carbide has been refined. Highlights: Black-Right-Pointing-Pointer Micro-hardness of primary M{sub 7}C{sub 3} carbide in Fe-Cr-C hardfacing alloy is 1594 HV. Black-Right-Pointing-Pointer RE inclusion Ce{sub 2}O{sub 2}S can be observed in the primary M{sub 7}C{sub 3} carbide. Black-Right-Pointing-Pointer Ce{sub 2}O{sub 2}S as heterogeneous nuclei of the Cr{sub 7}C{sub 3} is medium effective. Black-Right-Pointing-Pointer Primary carbide is most refined with 2 wt.% ceria additive.

• OSTI ID: 22163136
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: Complete Vol. 72; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADDITIVES
AUSTENITE
CERIUM OXIDES
CHROMIUM CARBIDES
FIELD EMISSION
HARDNESS
INCLUSIONS
MARTENSITE
MICROSTRUCTURE
OPTICAL MICROSCOPY
PRECIPITATION
RARE EARTHS
SCANNING ELECTRON MICROSCOPY
THERMODYNAMICS
WEAR RESISTANCE
WELDING
X-RAY DIFFRACTION