University of Oulu

Hamada, A., Ghosh, S., Ali, M., Jaskari, M., & Järvenpää, A. (2022). Studying the strengthening mechanisms and mechanical properties of dissimilar laser-welded butt joints of medium-Mn stainless steel and automotive high-strength carbon steel. Materials Science and Engineering: A, 856, 143936.

Studying the strengthening mechanisms and mechanical properties of dissimilar laser-welded butt joints of medium-Mn stainless steel and automotive high-strength carbon steel

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Author: Hamada, Atef1; Ghosh, Sumit2; Mohammed Ali, Mohammed2,3;
Organizations: 1Kerttu Saalasti Institute, Future Manufacturing Technologies (FMT), University of Oulu, Nivala, FI, 85500, Finland
2Materials and Mechanical Engineering Centre for Advanced Steels Research, University of Oulu, Oulu, FI, 90014, Finland
3Steel Technology Department, Central Metallurgical Research and Development Institute, Helwan, 11421, Cairo, Egypt
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 32.8 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-09-16


In this study, a post-weld heat treatment (PWHT) at a high temperature of 700 °C for 10 min was proposed to significantly improve the mechanical performance of dissimilar laser-welded butt joints between medium-manganese stainless steel (MMn-SS) and high-strength carbon steels (HS-CS) as base metals (BMs). Electron backscatter diffraction and transmission electron microscopy were employed to characterise the microstructures and study the deformation mechanisms in the paired metals of the dissimilar joints during PWHT and tensile straining. Micro-indentation hardness tests were performed to analyse the mechanical responses in the weld zones after PWHT. The results revealed that PWHT at 700 °C significantly affected the microstructure and mechanical strength of the BMs and their weldments. A fully tempered martensitic microstructure with recrystallised grain regions was formed in the fusion zones (FZs) of the weldments, which were processed at low and high specific point energies (SPEs) of 19, 25, and 30 J. BM HS-CS was significantly strengthened owing to the interphase precipitation hardening of vanadium carbide precipitates during the proposed PWHT. The strength-ductility balance of BM MMn-SS was improved by combining the martensitic transformation and mechanical twinning mechanisms. Although, the tensile strength of BM HS-CS increased from 500 to 630 MPa and that of the metal in the FZ decreased from 1100 to 800 MPa owing to PWHT. Hence, HS-CS is a weak metal for dissimilar joints, and joint failure was promoted in it.

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Series: Materials science & engineering. A, Structural materials: properties, microstructure and processing
ISSN: 0921-5093
ISSN-E: 1873-4936
ISSN-L: 0921-5093
Volume: 856
Article number: 143936
DOI: 10.1016/j.msea.2022.143936
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: The authors express their gratitude to the Interreg Nord Program and the Regional Council of Lapland for funding this research through the InTeMP project, No. NYPS 20202486. Also, “Jane and Aatos Erkko Foundation” is appreciated for partly funding this study. Outokumpu Stainless Oy (Tornio, Finland) and SSAB Europe Oy (Raahe, Finland), are gratefully acknowledged for providing the experimental materials.
Copyright information: © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (