PSI - Issue 71

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ScienceDirect

Procedia Structural Integrity 71 (2025) 95–102

5 th International Structural Integrity Conference & Exhibition (SICE 2024) Numerical Assessments of Cyclic Plastic Deformation and Strain Gradients in Dissimilar Metal Welds Sudarshan Solanki * 1,2 , Punit Arora 1,2 ,Suneel K Gupta 1,2 1 Homi Bhabha National Institute, Anushaktinagar, Mumbai – 400094, India 2 Reactor Safety Division, Bhabha Atomic Research Centre (BARC), Mumbai-400085, India *sudarshansolanki1997@gmail.com Abstract The present work is aimed at numerical assessment of dissimilar metal welds under pure axial and pure torsion cyclic loading conditions. Finite element analyses have been performed to quantify the strain gradient on hot-wire narrow-groove DMWs of SA508 Gr.3 Cl.1 and SS304LN with SS308L filler material. The elastic plastic finite element analyses have been performed using three-decomposed Chaboche material models of these segments (two parent materials and one weld material). The remote strain is controlled to attain maximum total von-Mises equivalent strain amplitudes of 1%, 0.75%, 0.5%, and 0.35% in the gauge region of weldment. The quantifications of strain gradients under different strain amplitudes and remote loading conditions have been performed in radial and axial directions. Fatigue life estimation is performed for different equivalent strain amplitudes, utilizing material specific strain-life equations. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SICE 2024 organizers 1. Introduction Dissimilar Metal Welds (DMWs) are generally used in connecting the Reactor Pressure Vessel (RPV) nozzle with the primary heat transport pipeline of a typical Pressurized Water Reactor (PWR). The RPV nozzle is, in general, made of Low-Alloy Steel (LAS) material and the heat transport piping material is austenitic Stainless Steel (SS). This necessitated the existence of DMW in the primary loop to connect LAS with SS. To assess the structural integrity of such weld joints under envisaged service induced cyclic loading conditions, it is necessary to study the cyclic response of different regions (two parent metals and one weld metal) of the weldment. Relative cyclic plastic deformation governs the initiation of fatigue cracks in such DMW. In this view, it becomes important to study the cyclic stress-strain response of different regions. Furthermore, the distinct yield strengths and flow properties of different regions establish strain gradients. These strain gradients also govern fatigue damage. Keywords: Material Discontinuity; Dissimilar Metal Welds; Strain Gradient; Finite Element Analysis.

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SICE 2024 organizers 10.1016/j.prostr.2025.08.014