Hydrogen trapping in bearing steels: mechanisms and alloy design
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Authors
Szost, Blanka Angelika
Advisors
Rivera-Diaz-del-Castillo, Pedro Eduardo Jose
Date
2013-02-05Awarding Institution
University of Cambridge
Author Affiliation
Department of Materials Science and Metallurgy
Murray Edwards College
Qualification
Doctor of Philosophy (PhD)
Language
English
Type
Thesis
Metadata
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Szost, B. A. (2013). Hydrogen trapping in bearing steels: mechanisms and alloy design (Doctoral thesis). https://doi.org/10.17863/CAM.14274
Abstract
Hydrogen embrittlement is a problem that offers challenges both to technology and to the theory of metallurgy. In the presence of a hydrogen rich environment, applications such as rolling bearings display a significant decrease in alloy strength and accelerated failure due to rolling contact fatigue. In spite of these problems being well recognised, there is little understanding as to which mechanisms are present in hydrogen induced bearing failure.
The objective of this thesis are twofold. First, a novel alloy combining the excellent
hardness of bearing steels, and resistance to hydrogen embrittlement, is proposed. Second, a new technique to identify the nature of hydrogen embrittlement in bearing
steels is suggested. The new alloy was a successful result of computer aided alloy design; thermodynamic and kinetic modelling were employed to design a composition and heat treatment combining (1) fine cementite providing a strong and ductile microstructure, and (2) nano-sized vanadium carbide precipitates acting as hydrogen traps. A novel technique is proposed to visualise the migration of hydrogen to indentation-induced cracks. The observations employing this technique strongly suggest that hydrogen enhanced localised plasticity prevails in bearing steels. While proposing a hydrogen tolerant bearing steel grade, and a new technique to visualize hydrogen damage, this thesis is expected to aid in increasing the reliability of bearings operating in hydrogen rich environments.
Keywords
hydrogen embrittlement, rolling contact fatigue, bearing steels, thermodynamic modelling, kinetic modelling, thermal desorption, hydrogen diffusion, hydrogen damage
Sponsorship
This work was supported by SKF Engineering and Research Centre and financed by SKF AB.
Identifiers
This record's DOI: https://doi.org/10.17863/CAM.14274
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