The impact of axi-symmetric boundary conditions on predicted residual stress and shrinkage in a PWR nozzle dissimilar metal weld
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Date
2012-07-15
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Publisher
American Society of Mechanical Engineers (ASME)
Abstract
Simulation of a dissimilar metal weld (DMW) in a pressurised water reactor (PWR) nozzle was performed to predict both axial distortion and hoop residual stresses in the weld. For this work a computationally efficient axi-symmetric finite element (FE) simulation was carried out rather than a full 3D analysis. Due to the 2-dimensional nature of the analysis it was necessary to examine the effect of structural restraint during welding of the main dissimilar metal weld (DMW). Traditionally this type of analysis is set up to allow one end of the structure, in this case the safe-end forging, to be unrestrained in the axial direction during welding. In reality axial expansion and subsequent contraction of deposited weld metal at the current torch position is restrained by solidified material both ahead and behind the torch. Thus the conventional axi-symmetric analysis is under-restrained in the axial direction at least during the early weld passes. The significance of this was examined by repeating the current simulation with the safe-end forging fixed to limit expansion during the heat up cycle. Contraction was however, allowed during cooling cycle. This modified boundary control method provided a significantly improved prediction of the axial distortion across the weld as well as improved prediction of through wall axial and hoop residual stresses. Copyright © 2012 The American Society of Mechanical Engineers
Description
Keywords
Boundary-value problems, Metals, Nozzles, Shrinkage, Residual stresses, Simulation, Forging, Welding, Finite element method, Thermodynamic cycles
Citation
Bendeich, P. J., Muránsky, O., Hamelin, C. J., Smith, M. C., & Edwards, L. (2012). The impact of axi-symmetric boundary conditions on predicted residual stress and shrinkage in a PWR nozzle dissimilar metal weld. Paper presented at the ASME 2012 Pressure Vessels and Piping Conference, Toronto, Ontario, Canada, July 15–19, 2012. In ASME 2012 Pressure Vessels and Piping Conference, Volume 6, Materials and fabrication, Parts A and B : July 15-19, 2012, Toronto, Ontario, Canada, (Vol. 55058, pp. 1139-1145). New York: American Society of Mechanical Engineers. doi:10.1115/PVP2012-78407