PSI - Issue 68

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2025) 000–000

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 68 (2025) 420–424

European Conference on Fracture 2024 Improvement In Fatigue Properties Of Welded Joints Using Crack Initiation Resistant Steel Part 1: Fatigue Strength Of Weld Heat Affected Zone And Cruciform Fillet Welded Joints Takanori Ito a, *,Yasuhito Takashima a , Masao Kinefuchi a a Kobe steel Ltd., Technical Development Group, 1-5-5 Takatsukadai, Nishi-ku, Kobe, Hyogo, Japan Abstract This study investigated whether the newly developed 490 MPa strength class steel, enhanced with solid solution elements, demonstrates superior fatigue properties in welded joints. The fatigue resistance of the Heat Affected Zone (HAZ) was assessed using simulated heat cycle tests. Subsequently, the evaluation was conducted using cruciform welded joints. The results showed that the fatigue strength of the developed steel exceeded that of conventional steel even within the HAZ microstructure. Additionally, it exhibited high fatigue strength in the welded joints as well. Overall, the developed steel offers superior fatigue strength in the HAZ, attributed to solid solution strengthening, and holds potential for improved fatigue properties in welded joints. © 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 ECF24 organizers Keywords: Fatigue ; Fatigue life ; Solid solution strengthening ; Heat affected zone ; Cruciform fillet welded joint 1. Introduction In welded structures, suppressing fatigue failures in welded joints is crucial. The fatigue process of metals is mainly divided into crack initiation and crack propagation. There have been several studies reported on the © 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 ECF24 organizers

* Corresponding author. Tel.: +81-78-992-5503 E-mail address: ito.takanori@kobelco.com

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 ECF24 organizers

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 ECF24 organizers 10.1016/j.prostr.2025.06.076