PSI - Issue 38

Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2021) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2021) 000 – 000

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 38 (2022) 466–476

© 2021 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 the scientific committee of the Fatigue Design 2021 Organizers © 2021 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 the scientific committee of the Fatigue Design 2021 Organizers Fatigue tests were performed in tension (R = 0.1) on longitudinal stiff ner weld d specimens without overload to stablish the reference and specimens after one overload for three levels (corresponding to a local stress clos to the weld toe equal to the yield tress (YS), 1.25·YS and 1.56·YS). The fatigue r ults show an increase of fatigue str ngth, after one overload, if the local stress near the weld toe is over than YS. Greater the overload is, better the fatigue strength is. The residual stress analysis shows a significant relaxation of the tensile residual stresses after the overload, that explains the performance in fatigue. © 2021 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 the scientific committee of the Fatigue Design 2021 Organizers FATIGUE DESIGN 2021, 9th Edition of the International Conference on Fatigue Design Influence of overload on fatigue behaviour of longitudinal non-load carrying welded joints Isabel HUTHER a , Fabien LEFEBVRE a , Benaouda ABDELLAOUI b , Vincent LERAY c a Cetim, 52 av Félix Louat, Senlis 60300, France, b Cetim, 7 rue de la Presse, St Etienne 42000, France c Nov-BLM, 15 rue de la métallurgie , Carquefou 44470, France Abstract Controlled overload techniques such as initial overload or proof load) are often used to verify the structural integrity of the mechanical systems. For example, the cranes are subjected to proof load before start-up, the turbomachinery to over-speed and pressure vessels to internal over-pressure. These initial overload techniques are often imposed by Standards like ASTM or DNV which define overload conditions to apply based on professional knowledge. However, no technical justifications, nor beneficial or negative effects are usually given on in-service behaviour. The aim of this study is to evaluate the effect of one overload on the fatigue behaviour for various levels of plastic strains on welded specimens in S355 steel grade. The hypothesis made is that the initial overload will introduce compressive residual stresses at the weld toe, the area where the fatigue crack initiates and propagates. These stresses would normally have a beneficial effect on fatigue strength as after hammer-peening. Fatigue tests were performed in tension (R = 0.1) on longitudinal stiffener welded specimens without overload to establish the reference and specimens after one overload for three levels (corresponding to a local stress close to the weld toe equal to the yield stress (YS), 1.25·YS and 1.56·YS). The fatigue results show an increase of fatigue strength, after one overload, if the local stress near the weld toe is over than YS. Greater the overload is, better the fatigue strength is. The residual stress analysis shows a significant relaxation of the tensile residual stresses after the overload, that explains the performance in fatigue. FATIGUE DESIGN 2021, 9th Edition of the International Conference on Fatigue Design Influence of overload on fatigue b haviour of longitudinal non-load carrying welded joints Isabel HUTHER a , Fabien LEFEBVRE a , Benaouda ABDELLAOUI b , Vincent LERAY c a Cetim, 52 av Félix Louat, Senlis 60300, France, b Cetim, 7 rue de la Presse, St Etienne 42000, France c Nov-BLM, 15 rue de la métallurgie , Carquefou 44470, France Abstract Controlled overload t chniqu s such as initial overload or proof load) are often used t verify the structural integrity of the mechanical syst ms. For example, the cranes are subjected to proof loa before start-up, the turbomachinery to over-speed and pressure ssels to internal over-pressure. These initial overload techniques are often imposed by Standards like ASTM or DNV w ich define overload c nditions to apply based on professi al knowledg . However, no technical justifications, nor beneficial or negative effects ar usually given on in-service b haviour. The aim of this study is to valuate the effect of one overload on the fatigue behaviour for various levels of plastic strains welded p cimens in S355 steel grade. The hypothesis made is that the initial overload will introduce compressive residual stresses at the weld toe, the area wh re the fatigu crack initiates and pr pagates. These stresses would nor ally have a benefici l effect on fatigu str ngth as after ha mer-pe ning.

Keywords: fatigue behaviour; welded-joint; steel; overload

Keywords: fatigue behaviour; welded-joint; steel; overload

2452-3216 © 2021 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 the scientific committee of the Fatigue Design 2021 Organizers 2452-3216 © 2021 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 the scientific committee of the Fatigue Design 2021 Organizers

2452-3216 © 2021 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 the scientific committee of the Fatigue Design 2021 Organizers 10.1016/j.prostr.2022.03.047