University of Oulu

Pallaspuro, S., Yu, H., Kisko, A., Porter, D., & Zhang, Z. (2017). Fracture toughness of hydrogen charged as-quenched ultra-high-strength steels at low temperatures. Materials Science and Engineering: A, 688, 190–201.

Fracture toughness of hydrogen charged as-quenched ultra-high-strength steels at low temperatures

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Author: Pallaspuro, Sakari1; Yu, Haiyang2; Kisko, Anna1;
Organizations: 1Materials and Production Engineering, Centre for Advanced Steels Research, University of Oulu, Finland
2Department of Structural Engineering, Faculty of Engineering Science and Technology, NTNU, Norway
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 2.5 MB)
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Language: English
Published: Elsevier, 2017
Publish Date: 2019-02-03


The effect of hydrogen on the fracture and impact toughness of ultra-high-strength steels at sub-zero temperatures in the transition temperature region has been investigated with arctic applications in mind. Two types of as-quenched microstructure were studied, i.e. autotempered martensite and a mixture of martensite and bainite, both having yield strengths close to 1000 MPa. These were charged with hydrogen using passive cathodic protection and then tested in both the charged and uncharged condition at sub-zero temperatures. Hydrogen contents were measured with melt-extraction. Fractography, kernel average misorientation measurements and cohesive zone modelling were used to analyse the results considering the degree and the active mechanisms of hydrogen embrittlement. It is shown that hydrogen embrittlement is present at sub-zero temperatures, causing an increase in fracture toughness reference temperature T0 and a small decrease in deformation capability. The relationship between the T0 and the impact toughness transition temperature T28J, which, in the case of ultra-high-strength steel, deviates from that observed for lower strength steels, is proposed to be affected by the hydrogen content.

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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: 688
Pages: 190 - 201
DOI: 10.1016/j.msea.2017.02.007
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This work has been done as a part of a doctoral project within the BSA programme of DIMECC Ltd. Funding from the Finnish Funding Agency for Innovation (Tekes) and the participating companies is gratefully acknowledged. Mr. Pallaspuro would also like to thank Tekniikan edistämissäätiö (TES) and the University of Oulu Graduate School for financially supporting the visit to NTNU, Professor Roy Johnsen (NTNU), Bård Nyhus, Asle O. Hellesvik, Ann-Karin Kvernbråten and Tore Kristensen (SINTEF) for technical guidance and SSAB Europe Oy for the support provided and the material studied. Zhiliang Zhang would like to acknowledge the support of the HIPP project financed by the Research Council of Norway (Project 234130/E30).
Copyright information: © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http:/