University of Oulu

Shahriar Afkhami, Vahid Javaheri, Mohsen Amraei, Tuomas Skriko, Heidi Piili, Xiao-Ling Zhao, Timo Björk, Thermomechanical simulation of the heat-affected zones in welded ultra-high strength steels: Microstructure and mechanical properties, Materials & Design, Volume 213, 2022, 110336, ISSN 0264-1275,

Thermomechanical simulation of the heat-affected zones in welded ultra-high strength steels : microstructure and mechanical properties

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Author: Afkhami, Shahriar1; Javaheri, Vahid2; Amraei, Mohsen3,4;
Organizations: 1Laboratory of Steel Structures, LUT University, P.O. Box 20, 52850 Lappeenranta, Finland
2Materials and Mechanical Engineering, University of Oulu, 90014, Finland
3Laboratory of Laser Materials Processing and Additive Manufacturing, LUT University, Lappeenranta 53850, Finland
4Department of Mechanical and Materials Engineering, University of Turku, Turku, 20520, Finland
5Laboratory of Welding Technology, LUT University, P.O. Box 20, 53851 Lappeenranta, Finland
6The School of Civil and Environmental Engineering, UNSW Sydney, NSW 2052, Australia
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 11.7 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-01-05


Ultra-high strength steels (UHSS) have a determining role in construction and industry. Furthermore, welding as the primary joining process for steel has a similar role in promoting its applications. Therefore, welded UHSS have a vital role in related applications. However, due to their complex microstructures, these steels are more prone to harmful effects of welding heat input on the mechanical properties compared to mild steels. Thus, identifying the correlations between the microstructural transformations triggered by the heat input and the mechanical properties can lead to new insights and hindering the drawbacks. This study investigates the microstructures and mechanical properties of S960 (with a severe softening after welding) and S1100 (with a negligible decrease of the mechanical properties after welding) to understand the mechanisms behind the softening of welded UHSS. Microstructural analysis showed the formation of soft phases, e.g., ferrite and granular bainite, as the primary reason for the softening. Furthermore, tempered forms of martensite and bainite resulted in the simultaneous decrease of hardness and notch toughness. Finally, the applicabilities of two experimental approaches to predict hardness from microstructural constituents were evaluated for welded S960 and S1100 and proved to have relatively good reliability to detect their HAZ softened spots.

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Series: Materials & design
ISSN: 0264-1275
ISSN-E: 1873-4197
ISSN-L: 0264-1275
Volume: 213
Article number: 110336
DOI: 10.1016/j.matdes.2021.110336
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Copyright information: © 2021 The Authors. Published by Elsevier Ltd.This is an open access article under the CC BY-NC-ND license (