Title: ENPOWER - Investigations by Neutron Diffraction and Finite Element Analyses on Residual Stress Formation in Repair Welds Applied to Ferritic Steel Plates
Citation: Proceedings of the 2005 ASME Pressure Vessels and Piping Conference vol. PVP2005-71786 p. 1-9
Publisher: ASME
Publication Year: 2005
JRC N°: JRC30174
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC30174
Type: Articles in periodicals and books
Abstract: The European collaborative research project ENPOWER has as one of its main objectives the development of guidelines for the application of repair welds to safety critical components in nuclear power plants. In this ocntext letter box repair welds applied to thin ferritic steel plates to simulate repair of postulated shallow cracks have been manufactured for the purpose of experimental and numerical analysis of welding residual stresses. Two speciments have been procured, one of them prepared in accordance with a standard welding procedure, while in the second case a different procedure was followed in order to obtain extended martensite formation in th heat affected zone. Residual stresses have been determined in both speciments by neutron diffraction at the HFR of the JRC in Petten, The Netherlands. In parallel Institut de Soudure in France has performed a full 3-dimensional analysis of the residual stress field for the standard welding case taking into account the materials and phase transformations. The experimental data obtained for both specimens clearly suggest that the non-conventional welding procedure rendered higher maximum stress values. In the case of the standard welding procedure numerical and experimental data show a reasonable qualitative agreement. The maximum stress value was in both cases found in the same region of the material - in the base metal justundernaeth the weld pool - and in both cases found to be of similar magnitude (~800 MPa found in neutron diffraction and ~700 MPa found in numerical analysis). In this paper the experimental and numerical approaches are outlined and the obtained results are presented. In addition an outlook is given to future work to be performed on this part of the ENPOWER project. A main issue pending is the application of an optimized advanced post weld heat treatment in one of the two cases and the subsequent numerical and experimental determiniation of its impact on the residual stress field. At the same time further evaluation of the materials transformations due to welding is pursued.
JRC Directorate:Energy, Transport and Climate

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