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Title: Time-variant reliability of super-duplex stainless steel tubulars
Author: Renton, N. C.
ISNI:       0000 0001 3514 1397
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2007
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The development of high pressure-high temperature oil wells in the U.K.'s north sea province has led to the application of high-strength, corrosion resistant alloys for production tubulars. One such alloy is super-duplex stainless steel (SDSS). The cold-worked material combines high strength with excellent corrosion resistance properties as a result of its chromium, molybdenum, tungsten and nitrogen content. The material's macro properties are a function of its two-phase microstructure made up of roughly equal parts austenite and ferrite. Recent in-service failures of SDSS tubulars have identified gaps in the understanding of the material's properties. The study investigated the link between the microstructure of the material and its mechanical and corrosion behaviours. The results revealed that the microstructure of the material was highly anisotropic and varied through the pipe-wall as a result of manufacturing techniques. A method of measuring the crack resistance of the material was developed, with the results showing that the spatial arrangement of the microstrucure determined the crack resistance of the fracture plane. The properties of ferrite were identified as the limiting factor on the crack resistance of the material. The investigation also revealed that a small difference in chemical composition between the two phases led to the preferential dissolution of ferrite in aqueous oxygen bearing chloride environments.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available