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Title: Effects of microstructure and strain ageing on toughness of nuclear PWR reactor weld metals
Author: Farron, Victoria Jane
ISNI:       0000 0004 2692 739X
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2010
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The effects of microstructure and prestraining and ageing on ductile-to-brittle transition temperature, fracture toughness and cleavage fracture resistance of a multi-pass low-alloy ferritic steel weld metal have been investigated. The weld metal simulated submerged arc welds used in the fabrication of Sizewell B power station reactor pressure vessel. The study aimed to investigate differences in mechanical properties of a single microstructure; asdeposited and reheated microstructures and subjected to various mechanical tests. Additionally, to simulate the effects of irradiation embrittlement a number of specimens were prestrained and then statically strain aged. Charpy impact transition curves had obvious trends depending upon microstructure and condition, with microstructure having a significant influence on the transition region and upper-shelf impact energy level. Prestraining and ageing the specimens promoted an increase in the ductile-to-brittle transition temperature and reduction the upper shelf energy level for both microstructures. The extremes of behaviour were defined by the reheated as-received and as-deposited prestrained and aged conditions, being the “best” and “worst conditions” respectively. This trend was repeated with the cracktip opening displacement tests. A combination of factors decreases toughness for the asdeposited prestrained and aged condition, which exhibited the highest yield stress, and lowest work hardening exponent and the best cleavage fracture resistance. Such factors result in marked upwards shifts in Charpy impact transition curves and decease in the crack growth resistance curves.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TK Electrical engineering. Electronics Nuclear engineering