Oxygen-induced segregation during batch annealing of industrial steel coils

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dc.contributor.advisorSwart, H. C.
dc.contributor.advisorTerblans, J. J.
dc.contributor.authorWurth, Etienne
dc.date.accessioned2016-01-06T09:45:18Z
dc.date.available2016-01-06T09:45:18Z
dc.date.copyright2006-05
dc.date.issued2006-05
dc.date.submitted2006-05
dc.description.abstractThe development of diffusion welds between spirals of steel coils, during batch annealing, is of particular interest because it preve nts the coils from being unwound for further use. The physical metallurgy of iron and steel is exceedingly complicated and many of the complications arise from the behaviour of solutes, which segregate to surfaces and interfaces, which alter the mechanical behaviour. Segregation studies were done by measuring the APPH’s (Auger Peak to Peak Heights) of the segregating species (P, S, C and Ti) against annealing time during the annealing of an ultra low carbon (ULC) Ti stabilized steel between 550 and 800oC. The modified Darken model was used to describe the complex segregation behaviour of the species involved during annealing of the industrial steel. This was done by comparing the initial changes in fractional surface concentration of the segregating species against annealing time to the trends in the surface concentration changes as describe by the Darken model for a ternary alloy. Calculations were done, using Langmuir-McClean equations, to determine the change in effective segregation energy as a function of oxygen surface coverage. Oxidation was allowed after sputtered cleaning and segregation, these oxidation results were compared with each other. No C segregation occurred without oxygen in the system. Oxygen induced-segregation of Ti and C occurred at 700oC and 800oC. Oxidation occurred at 700oC and 800oC. It was found that the adsorption of oxygen on the surface profoundly influence the segregation rate of the species involved. The modified Darken model was successfully used to describe the oxygen induced-segregation process. The induced segregation may act as a possible source of the diffusion welds during batch annealing.en_ZA
dc.identifier.urihttp://hdl.handle.net/11660/1989
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA
dc.subjectDissertation (M.Sc. (Physics))--University of the Free State, 2006en_ZA
dc.subjectAnnealing of metalsen_ZA
dc.subjectSteel -- Heat treatmenten_ZA
dc.subjectSteel -- Metallurgy -- Oxygen processesen_ZA
dc.subjectLangmuir-McClean equationen_ZA
dc.subjectDarken modelen_ZA
dc.subjectSegregation energyen_ZA
dc.subjectLinear Least Squares (LLS)en_ZA
dc.subjectIndustrial steelen_ZA
dc.subjectOxygen induced segregationen_ZA
dc.subjectDiffusionen_ZA
dc.subjectOxidationen_ZA
dc.subjectAuger Electron Spectroscopy (AES)en_ZA
dc.titleOxygen-induced segregation during batch annealing of industrial steel coilsen_ZA
dc.typeDissertationen_ZA
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