Li, Wei (2011)
Ph.D. thesis, University of Birmingham.
S-phase can be created in austenitic stainless steels by low-temperature thermochemical treatments, which greatly enhanced their hardness, wear resistance and fatigue properties because of the supersaturation by interstitials. One of the technological challenges associated with S-phase surface engineering is that the maximum layer thickness of the S-phase layers is very thin. The thickness of S-phase is restricted by its metastability and precipitation will occur as a result of prolonged treatment.
In this project, the effect of in situ tensile stress on the formation of carbon S-phase on 316L austenitic stainless steel was investigated and it was demonstrated that the tensile stress thickened the S-phase layer by promoting the carbon diffusion in austenitic substrate. However, metastable carbides precipitated when applied tensile stress exceeded 40MPa.
The thermo-mechanical stability of carbon S-phase was studied by creeping (tensile stress) and HIPping (compressive stress) tests. The results showed that the compressive stress retard the decomposition of S-phase by impeding the carbon diffusion; on the other hand, tensile stress promoted the carbon diffusion.
The residual compressive and shear stresses in carbon S-phase was measured be 2.2 GPa and 132 MPa. The wear behaviour of carbon S-phase was studied by dry and oil lubricated reciprocating wear.
|Type of Work:||Ph.D. thesis.|
|School/Faculty:||Colleges (2008 onwards) > College of Engineering & Physical Sciences|
|Department:||School of Metallurgy and Materials|
Research from this thesis is published as
Wei Li, Xiaoying Li, Hanshan Dong,
Effect of tensile stress on the formation of S-phase during low-temperature plasma carburizing of 316L foil
Acta Materialia, Volume 59, Issue 14, August 2011, Pages 5765-5774, ISSN 1359-6454,
|Subjects:||TN Mining engineering. Metallurgy|
|Institution:||University of Birmingham|
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