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Title: Microstructural investigation of alloys used for power generation industries
Author: Krishna, Ram
ISNI:       0000 0004 2697 9544
Awarding Body: University of Leicester
Current Institution: University of Leicester
Date of Award: 2010
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Nickel based superalloys are currently being investigated for high temperature applications in advanced steam power plant operating at temperatures of 700˚C and above. Three nickel-based superalloys Inconel 617, Inconel 625 and Nimonic 263 alloys, which are of primary interest for boiler technology components such as furnace walls, superheater tubes, header and steam pipes, etc and for steam turbine technology components such as HP &IP cylinders, rotor forgings, casing and valve chest, blading, etc., have been evaluated for long and short term creep performance. Creep deformation processes occurring at high temperatures and stresses lead to the evolution of microstructures in the form of precipitation, precipitate coarsening and recovery effects. The deterioration in mechanical properties as a result of this microstructural change has been evaluated by hardness testing. This work discusses the microstructural evolution occurring in alloys in samples that have been creep exposed at a series of temperatures from 650°C to 775°C and for durations from 1000 to 45,000 hours using advanced FEGSEM, TEM, XRD and phase extraction techniques. The fractions and morphology of different phases, their locations during exposure to higher temperatures and probable creep fracture mechanism in these alloys are illustrated and discussed.
Supervisor: Hainsworth, Sarah Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: solid-solution strengthening creep intergranular grain boundary precipitates volume fraction fractography carbon replica thin foil M23C6 SEM TEM Inconel 617 Inconel 625 and Nimonic 263 alloys