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Microstructural evolution and creep damage accumulation in Grade 92 steel weld for steam pipe applications

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thesis
posted on 25.05.2017, 10:04 by Xu Xu
Grade 92 steel is a commonly used material for steam pipe and tube applications in the power generation industry. The advantages of Grade 92 steel include excellent creep resistance and sufficient corrosion resistance, which provide a long service lifetime expectancy for components. Grade 92 steel is typically heat treated by a normalisation process performed at approximately 1100°C followed by a tempering process at approximately 750°C. The resulting microstructure of Grade 92 steel is composed of a tempered martensitic matrix with secondary precipitates distributed both on lath and grain boundaries and within laths and grain interiors.
Welds in thick-section steam pipes made from Grade 92 steel are typically fabricated by a gas tungsten arc root process followed by a multi-pass submerged arc fill process. Post weld heat treatment (PWHT) is then performed on as-fabricated welds, helping to relieve residual stress and stabilise the martensitic microstructure. The microstructures in the HAZs of these complicated welds have not to date been fully understood. There is a lack of systematic microstructural investigations to define the different regions of the microstructure across the HAZ as a function of the welding process. [Continues.]

Funding

EPRI

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Publisher

Loughborough University

Rights holder

© Xu Xu

Publication date

2017

Notes

A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.

Language

en

Qualification name

PhD

Qualification level

Doctoral

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