Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopy

High strength combined with sufficient toughness is a fundamental prerequisite for steel in the field of lightweight construction. Joining high-strength steels by means of welding requires the use of highly advanced filler metals and a stress-relief post-weld heat treatment (PWHT) for optimum perfor...

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Main Authors: Daniel Schrittwieser, Hannes Pahr, Michael Musi, Andreas Landefeld, Oleksandr Glushko, Ronald Schnitzer
Format: Article
Language:English
Published: Elsevier 2024-11-01
Series:Journal of Materials Research and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2238785424024578
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author Daniel Schrittwieser
Hannes Pahr
Michael Musi
Andreas Landefeld
Oleksandr Glushko
Ronald Schnitzer
author_facet Daniel Schrittwieser
Hannes Pahr
Michael Musi
Andreas Landefeld
Oleksandr Glushko
Ronald Schnitzer
author_sort Daniel Schrittwieser
collection DOAJ
description High strength combined with sufficient toughness is a fundamental prerequisite for steel in the field of lightweight construction. Joining high-strength steels by means of welding requires the use of highly advanced filler metals and a stress-relief post-weld heat treatment (PWHT) for optimum performance of the joint. However, such a heat treatment can lead to embrittlement in the weld metal. In this context, the present work deals with the influence of different PWHT holding temperatures on the microstructure and mechanical properties of a high-strength multipass all-weld metal to reveal the embrittlement phenomena. The all-weld metal was fabricated via gas metal arc welding using a metal cored wire with a minimum yield strength of 690 MPa. Charpy V-notch impact testing and tensile testing were carried out to characterize the strength and toughness of the all-weld metal in the as-welded condition and after a 2 h stress-relief PWHT at 520 °C, 580 °C, and 620 °C. The microstructure was characterized utilizing high-resolution techniques such as atom probe tomography and high-energy X-ray diffraction. The strength and toughness of the all-weld metal both decrease after PWHT with different holding temperatures. The cause for the observed embrittlement was found to be the formation of Mn-rich cementite precipitates. These carbides increase in size and phase fraction with increasing holding temperature and lead to a brittle transcrystalline cleavage fracture. Consequently, it was concluded that a gas metal arc welded joint with the investigated filler metal should not be exposed to stress-relief PWHT at temperatures higher than 580 °C.
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spelling doaj-art-22456c41416d46e09e14027569f73b092024-12-26T08:54:55ZengElsevierJournal of Materials Research and Technology2238-78542024-11-013352895298Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopyDaniel Schrittwieser0Hannes Pahr1Michael Musi2Andreas Landefeld3Oleksandr Glushko4Ronald Schnitzer5Department of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria; Corresponding author.voestalpine Böhler Welding Austria GmbH, Böhler-Welding-Straße 1, 8605 Kapfenberg, AustriaDepartment of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, AustriaDepartment of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, AustriaDepartment of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, AustriaDepartment of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, AustriaHigh strength combined with sufficient toughness is a fundamental prerequisite for steel in the field of lightweight construction. Joining high-strength steels by means of welding requires the use of highly advanced filler metals and a stress-relief post-weld heat treatment (PWHT) for optimum performance of the joint. However, such a heat treatment can lead to embrittlement in the weld metal. In this context, the present work deals with the influence of different PWHT holding temperatures on the microstructure and mechanical properties of a high-strength multipass all-weld metal to reveal the embrittlement phenomena. The all-weld metal was fabricated via gas metal arc welding using a metal cored wire with a minimum yield strength of 690 MPa. Charpy V-notch impact testing and tensile testing were carried out to characterize the strength and toughness of the all-weld metal in the as-welded condition and after a 2 h stress-relief PWHT at 520 °C, 580 °C, and 620 °C. The microstructure was characterized utilizing high-resolution techniques such as atom probe tomography and high-energy X-ray diffraction. The strength and toughness of the all-weld metal both decrease after PWHT with different holding temperatures. The cause for the observed embrittlement was found to be the formation of Mn-rich cementite precipitates. These carbides increase in size and phase fraction with increasing holding temperature and lead to a brittle transcrystalline cleavage fracture. Consequently, it was concluded that a gas metal arc welded joint with the investigated filler metal should not be exposed to stress-relief PWHT at temperatures higher than 580 °C.http://www.sciencedirect.com/science/article/pii/S2238785424024578High-strength weld metalPost-weld heat treatmentAtom probe tomographyHigh-energy X-ray diffractionTemper embrittlementCementite
spellingShingle Daniel Schrittwieser
Hannes Pahr
Michael Musi
Andreas Landefeld
Oleksandr Glushko
Ronald Schnitzer
Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopy
Journal of Materials Research and Technology
High-strength weld metal
Post-weld heat treatment
Atom probe tomography
High-energy X-ray diffraction
Temper embrittlement
Cementite
title Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopy
title_full Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopy
title_fullStr Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopy
title_full_unstemmed Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopy
title_short Revealing the embrittlement phenomena after post-weld heat treatment of high-strength weld metal using high-resolution microscopy
title_sort revealing the embrittlement phenomena after post weld heat treatment of high strength weld metal using high resolution microscopy
topic High-strength weld metal
Post-weld heat treatment
Atom probe tomography
High-energy X-ray diffraction
Temper embrittlement
Cementite
url http://www.sciencedirect.com/science/article/pii/S2238785424024578
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