University of Oulu

Latypova, R., Seppälä, O., Tun Nyo, T., Kauppi, T., Mehtonen, S., Hänninen, H., Kömi, J., & Pallaspuro, S. (2023). Influence of prior austenite grain structure on hydrogen-induced fracture in as-quenched martensitic steels. Engineering Fracture Mechanics, 281, 109090.

Influence of prior austenite grain structure on hydrogen-induced fracture in as-quenched martensitic steels

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Author: Latypova, Renata1; Seppälä, Oskari1; Nyo, Tun Tun1;
Organizations: 1Materials and Mechanical Engineering, Centre for Advanced Steels Research (CASR), University of Oulu, P.O. Box 4200, 90014 Oulu, Finland
2Arctic Steel and Mining RDI-group, Lapland University of Applied Science, 94600 Kemi, Finland
3SSAB, P.O. Box 93, 92101 Raahe, Finland
4Aalto University School of Engineering, Department of Mechanical Engineering, P.O. Box 14200, FI-00076 AALTO, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 17.7 MB)
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Language: English
Published: Elsevier, 2023
Publish Date: 2023-03-21


Suppressing hydrogen embrittlement in martensitic steels is a longstanding challenge. Here, we studied the effects of prior austenite grain (PAG) shape and size with a 0.25C steel utilising novel in situ H-charging, constant-displacement Tuning-fork testing (TFT) and H-permeation tests. Anisotropic elongated PAG structure has enhanced HE resistance transverse to the rolling direction (RD) with slower crack propagation rate (CPR) and quasi-cleavage fracture. Larger elongated grains are prone to intergranular fracture when crack propagates in RD. Reaustenitised equiaxed PAGs fail with intergranular cracking, which accelerates max CPR up to threefold compared to quasi-cleavage. All the microstructures have similar H-diffusion ∼5 × 10−7 cm2/s and density of reversible H-traps NT ∼ 3 × 1016, irrespective of PAG surface area, indicating that PAG boundaries are not effective diffusion paths. Deformed PAG boundaries mitigate susceptibility to intergranular cracking.

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Series: Engineering fracture mechanics
ISSN: 0013-7944
ISSN-E: 1873-7315
ISSN-L: 0013-7944
Volume: 281
Article number: 109090
DOI: 10.1016/j.engfracmech.2023.109090
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This research was supported by Business Finland Oy, and projects ISA – Intelligent Steel Applications and FOSSA–Fossil-Free Steel Applications, are acknowledged. Academy of Finland (#337108) is thanked for funding, too.
Academy of Finland Grant Number: 337108
Detailed Information: 337108 (Academy of Finland Funding decision)
Copyright information: © 2023 The Authors. This is an open access article under the CC BY license (