Title: Combination of Stimulation and Experiment in Designing Repair Weld Strategies - A Feasibility Study
Authors: KEPPAS LoukasWIMPORY Robert CharlesKATSAREAS Dimitris E.OHMS Carsten
Citation: NUCLEAR ENGINEERING AND DESIGN vol. 240 no. 10 p. 2897-2906
Publisher: ELSEVIER SCIENCE SA
Publication Year: 2010
JRC Publication N°: JRC57380
ISSN: 0029-5493
URI: www.elsevier.com/locate/nucengdes
http://publications.jrc.ec.europa.eu/repository/handle/JRC57380
DOI: 10.1016/j.nucengdes.2010.05.034
Type: Articles in Journals
Abstract: Numerical simulations, based on an off-the-self commercial finite element (FE) code and experimental tests using the neutron diffraction (ND) technique, are combined in an attempt to evaluate post-weld heat treatment (PWHT) of a letterbox-type repair weld, in respect of its effect on the residual stress field. 21/4CrMo steel plates with an 18-pass repair weld were heat treated at various temperature levels and for different durations. Due to the prohibitive cost of a complete residual stress mapping, ND tests were performed only at selected specimen locations. In this sense, FE simulation acts as a supplement to ND, since it predicts the complete residual stress field. Uncoupled quasi-static thermoelasticity in conjunction with an element activation/deactivation technique, simulating deposition of new weld material, are combined in a 3D FE analysis. Grouping of the 18 weld beads in lumps, following a sensitivity analysis, reduces computational costs to feasible levels, whereas a creep strain hardening law is used to simulate stress relaxation during PWHT. Computed residual stresses are compared to ND measurements for verification purposes. Comparison of heat treated specimen measurements to heat treated and untreated specimen predictions illustrates that PWHT has a strong effect on the residual stress field, achieving significant stress relaxation.
JRC Institute:Institute for Energy and Transport

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