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Hamelin C.J.,Australian Nuclear Science and Technology Organization | Muransky O.,Australian Nuclear Science and Technology Organization | Smith M.C.,Electricite de France | Smith M.C.,University of Manchester | And 4 more authors.
Acta Materialia | Year: 2014

Numerical finite element analyses were combined with experimental observation of a single-pass autogenous beam weld in SA508 Gr.3 Cl.1 ferritic steel. Two weldment sets were prepared using different weld heat inputs, resulting in different post-weld residual stress and ferritic phase distributions. Neutron diffraction was employed to measure the residual stress distribution while microhardness measurements were used to measure the post-weld phase distribution in each weldment. In both cases, the numerical model accurately predicts the ferritic phase distribution and residual stress field. Model predictions illustrate how the higher cooling rates associated with a faster torch speed result in an increased martensite volume fraction within the weldment. Consideration of both the transformation kinetics and transformation plasticity are proven to significantly improve model accuracy when comparing measured and predicted residual stress profiles. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Muransky O.,Australian Nuclear Science and Technology Organization | Smith M.C.,Electricite de France | Bendeich P.J.,Australian Nuclear Science and Technology Organization | Holden T.M.,Northern Stress Technologies | And 3 more authors.
International Journal of Solids and Structures | Year: 2012

The current paper presents a finite element simulation of the residual stress field associated with a three pass slot weld in an AISI 316LN austenitic stainless steel plate. The simulation is split into uncoupled thermal and mechanical analyses which enable a computationally less expensive solution. A dedicated welding heat source modelling tool is employed to calibrate the ellipsoidal Gaussian volumetric heat source by making use of extensive thermocouple measurements and metallographic analyses made during and after welding. The mechanical analysis employs the Lemaitre-Chaboche mixed hardening model. This captures the cyclic mechanical response which a material undergoes during the thermo-mechanical cycles imposed by the welding process. A close examination of the material behaviour at various locations in the sample during the welding process, clearly demonstrates the importance of defining the correct hardening and high temperature softening behaviour. The simulation is validated by two independent diffraction techniques. The well-established neutron diffraction technique and a very novel spiral slit X-ray synchrotron technique were used to measure the residual stress-strain field associated with the three-pass weld. The comparison between the model and the experiment reveals close agreement with no adjustable parameters and clearly validates the used modelling procedure. © 2012 Elsevier Ltd. All rights reserved.

Muransky O.,Australian Nuclear Science and Technology Organisation | Holden T.M.,Northern Stress Technologies | Kirstein O.,EES AB | James J.A.,Open University Milton Keynes | And 2 more authors.
Journal of Nuclear Materials | Year: 2013

The dual-phase alloy Zr2.5Nb alloy is an important nuclear material, because of its use in current and possible use in future nuclear reactors. It is, however, well-known that Zr2.5Nb weldments can fail through a time-dependent mechanism called delayed hydride cracking which is typically driven by the presence of tensile residual stresses. With a view to understanding the development of residual stresses associated with Zr2.5Nb welds the current study focuses on the evaluation of the residual stresses in a mock-up of a reactor beam tube flange made from Zr2.5Nb0.9Hf. The present results suggests that, like ferritic welds which undergo a solid-state phase transformation upon welding, Zr2.5Nb0.9Hf welds also develop high tensile residual stresses in the heat-affected zone whereas the stresses closer to the weld tip are reduced by the effects of the β → α solid-state phase transformation. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Holden T.M.,Northern Stress Technologies
Canadian Journal of Physics | Year: 2010

The origins of the method, which relies on the high penetration of thermal neutrons through most industrial materials, in the late 1970s and 1980s and its development up to the present time are described. The basic steps from the measurement of lattice spacing to the calculation of stress are outlined. The length scales on which strains and stresses are manifest have a bearing on the interpretation of strain in terms of stress. A number of examples of macroscopic strain or stress fields are described where these scale considerations, as well as gradients of solute concentration that affect the interpretation of strain, matter. The strains on the length scale of the grains provide useful information about the elasticity and plasticity of materials, particularly in materials of lower symmetry than cubic. Finally, a number of future directions are suggested, which are enabled by the new intense neutron sources and improved equipment built in the last few years.

Muransky O.,Australian Nuclear Science and Technology Organisation | Bendeich P.J.,Australian Nuclear Science and Technology Organisation | Smith M.C.,Electricite de France | Kirstein O.,Australian Nuclear Science and Technology Organisation | And 2 more authors.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

In this paper finite element simulation and neutron diffraction measurements are employed to assess the residual stresses in an AISI 316LN austenitic stainless steel plate containing a three-pass finite length weld in a machined slot. This work forms a part of the Task Group 4 (TG4) measurement and simulation round robin being undertaken by the NeT European network. Finite element (FE) simulations were carried out using the FEAT-WMT and ABAQUS commercial finite element packages. the welding process was modelled both using a 3D moving-heat source (MHS) which is spatially correct but computationally expensive and using a simplified "block-dumped" methodology (BD) in which an entire weld bead is deposited simultaneously. This does not reproduce the effects of welding torch movement, but is computationally less expensive. the mechanical analyses used combined isotropickinematic material constitutive models with a two-stage annealing functionality to remove plastic strain accumulated at high temperatures. the finite element predictions of weld residual stress are compared with neutron diffraction measurements obtained on the KOWARI diffractometer at the OPAL reactor at ANSTO. Copyright © 2010 by ASME.

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