20th International Conference on Structural Mechanics in Reactor Technology (SMiRT 20) Espoo, Finland, August 9-14, 2009 SMiRT 20-Division I, Paper 3142
Effect of hardening model on the weld residual stress field in pipe girth welds Jonathan G. Mullins1 and Jens Gunnars1 1
Inspecta Technology AB, Lindhagensterrassen 1, Stockholm, Sweden, e-mail:
[email protected],
[email protected]
Keywords: Weld residual stress, stainless steel, strain hardening.
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ABSTRACT
Accurate estimates of weld residual stress fields in welded components are necessary for conducting structural assessments where stress corrosion cracking and/or fatigue are of interest. The aim of the study is to determine whether finite element simulations of the weld residual stress field give the best agreement with experimental measurements if an isotropic, kinematic or mixed material hardening model is used. Two girth weld geometries are considered with thicknesses of 19mm and 65mm and radius to thickness ratios of 10.5 and 2.8, respectively. Welding simulations were conducted using isotropic, kinematic and mixed hardening models. The isotropic hardening model gave the best overall agreement with experimental measurements. The mixed hardening model gave good agreement for predictions of the hoop stress but tended to under predict the magnitude of the axial stress. The kinematic hardening model consistently under predicted the magnitude of both the axial and hoop stress. Although the conclusions need to be confirmed by further simulations and measurements for other geometries, an isotropic hardening model is recommended as the current best alternative for use in welding simulations.
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INTRODUCTION
Detailed knowledge of the residual stress fields that result from welding processes is critical to performing damage tolerance analyses of nuclear structures. The through-thickness distribution of these weld residual stress field