Abstract
Prior austenite grain (PAG) structure is an important factor influencing hydrogen embrittlement (HE) susceptibility of ultrahigh-strength steels. In this study, the effect of PAG shape and size on HE behaviour is investigated using a novel tuning-fork testing method and hydrogen thermal desorption spectroscopy (TDS). Different PAG structures were acquired via re-austenitization (860 °C = A860, 960 °C = A960) and rapid quenching of an as-received 500 HBW direct-quenched (DQ) steel, which has an auto-tempered lath-martensitic microstructure and elongated PAG morphology. Fractography reveals different crack propagation mechanisms depending on the PAG shape. With the elongated PAG structure, hydrogen-induced crack propagation transverse to elongated PAGs was transgranular quasi-cleavage. Propagation was partially intergranular with the equiaxed PAG structures, regardless of the PAG size, leading to equally faster fracture. The TDS results show that there are no significant differences between the total hydrogen contents, but re-austenitized A860 and A960 steels contain a higher fraction of weakly trapped hydrogen. This indicates that the PAG boundaries are not the dominant hydrogen traps, and the different crack propagation mechanisms are rather linked to the geometrical shape of the grain structure.
| Original language | English |
|---|---|
| Title of host publication | 23rd European Conference on Fracture, ECF 2022 |
| Editors | Pedro Moreira, Luis Reis |
| Publisher | Elsevier |
| Pages | 871-878 |
| Number of pages | 8 |
| ISBN (Electronic) | 978-1-7138-7030-2 |
| DOIs | |
| Publication status | Published - 2022 |
| MoE publication type | A4 Conference publication |
| Event | European Conference on Fracture - Funchal, Portugal Duration: 27 Jun 2022 → 1 Jul 2022 Conference number: 23 |
Publication series
| Name | Procedia Structural Integrity |
|---|---|
| Volume | 42 |
| ISSN (Electronic) | 2452-3216 |
Conference
| Conference | European Conference on Fracture |
|---|---|
| Abbreviated title | ECF |
| Country/Territory | Portugal |
| City | Funchal |
| Period | 27/06/2022 → 01/07/2022 |
Funding
This research was supported by Business Finland Oy and Academy of Finland (#337108). The projects ISA – Intelligent Steel Applications and FOSSA– Fossil-Free Steel Applications, are acknowledged. The authors wish to thank the technical staff of the Materials and Mechanical Engineering unit at the University of Oulu for their help with experimental work and sample preparation. This research was supported by Business Finland Oy and Academy of Finland (#337108). The projects ISA - Intelligent Steel Applications and FOSSA- Fossil-Free Steel Applications, are acknowledged. The authors wish to thank the technical staff of the Materials and Mechanical Engineering unit at the University of Oulu for their help with experimental work and sample preparation.
Keywords
- hydrogen embrittlement
- prior austenite grain structure
- steel
- TDS
- tuning-fork test