Angel, O (2023) Quasi-Static Fracture Behaviour of AISI 304L and CA6NM. Doctoral thesis, Liverpool John Moores University.

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Abstract

Nuclear transport packages are required to transport radioactive material for a variation of reasons such as the transport of new fuel to reactor sites. Depending on the type of nuclear transport package, AISI 304L is used for various components such as internal/external shock absorbers and outer containment structures. Literature regarding CA6NM suggests that the material provides the mechanical properties to be used for thick wall castings for nuclear transport packages. The aim of this thesis was to obtain data characterising the plasticity and fracture behaviour of two grades of stainless steel, AISI 304L and CA6NM when subjected to a range of multiaxial loading.

Nuclear transport packages must pass a series of testing standards regulated by the IAEA before they can be licenced for use. The main motivating factor in this study was to acquire data regarding the failure of AISI 304L and CA6NM, by producing a fracture locus which could be utilised to assist structural integrity assessments for the design of nuclear transport packages.

The experimental testing programme had 4 main phases of testing, a total of 200 tests were performed at ambient temperature under quasi-static conditions on test specimens having 15 different geometries. The methodology used DIC in parallel with FE analysis, to find the equivalent fracture strain, average stress triaxiality and average Lode angle parameter over the load history.

Initially, the fracture initiation point was assumed to be at the location of the maximum plastic equivalent strain of the FE analysis. However, fracture initiation at the critical location of the geometries designed to provide pure shear data, occurred at the point of maximum tensile stress. This led to an investigation to extract data from a central node located in the shear region or alternatively averaging the whole of the failure zone of the specimen. Various fracture loci were constructed at the moment of failure but using the different methods for extracting the data. From this a strain-based criterion for AISI 304L and CA6NM was produced. Analytical expressions of the fracture envelope for each method can be utilised for practical relevance, regarding nuclear transport packages depending on the failure model. Methods developed in this thesis can be used for other materials and can aid future experiments investigating plasticity and fracture behaviour for factors such as a range of strain rates and temperatures.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	AISI 304L; CA6NM; Fracture Locus; Lode Parameter; Stress Triaxiality
Subjects:	H Social Sciences > HE Transportation and Communications T Technology > TA Engineering (General). Civil engineering (General) T Technology > TK Electrical engineering. Electronics. Nuclear engineering
Divisions:	Engineering
SWORD Depositor:	A Symplectic
Date Deposited:	22 Aug 2024 09:50
Last Modified:	22 Aug 2024 09:50
DOI or ID number:	10.24377/LJMU.t.00024002
Supervisors:	English, R, Ren, J and Rothwell, G
URI:	https://researchonline.ljmu.ac.uk/id/eprint/24002

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