Design considerations for hydrogen embrittlement resistance: The influence of dislocation density and substructures on hydrogen-assisted cracking in high-Mn TWIP steel
This study investigates the hydrogen embrittlement (HE) behavior of high-manganese TWIP-assisted steel by comparing microstructures with high and low dislocation (HD and LD) densities. The HD microstructure exhibited higher hydrogen absorption and a greater density of hydrogen-assisted cracks (HACs)...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-08-01
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| Series: | Materials & Design |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S026412752500718X |
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| Summary: | This study investigates the hydrogen embrittlement (HE) behavior of high-manganese TWIP-assisted steel by comparing microstructures with high and low dislocation (HD and LD) densities. The HD microstructure exhibited higher hydrogen absorption and a greater density of hydrogen-assisted cracks (HACs) compared to the LD microstructure. Despite lower hydrogen diffusivity, the HD samples experienced significant elongation loss under hydrogen charging, indicating that minimizing pre-existing dislocation structures as a design criterion can enhance HE resistance in high-Mn TWIP steels. This behavior was primarily attributed to the rapid development of HACs. The accelerated failure in HD resulted from two key factors: (1) dislocation multiplication, which increased hydrogen trapping and facilitated crack nucleation, and (2) rapid degradation of the hydrogen-affected region (HAR), which reduced its ability to accommodate deformation, thereby increasing local stress and promoting void formation and coalescence in the hydrogen-unaffected region, ultimately leading to premature fracture. Fractography analysis revealed predominantly intergranular fracture in LD samples. The HE mechanism in LD follows the HELP + HEDE model, where HEDE dominates due to high local hydrogen concentration, and HELP contribution is negligible. In contrast, HD samples exhibited quasi-cleavage features, shallow dimples, and limited intergranular facets, reflecting a combination of HELP-mediated HEDE and localized HELP-driven damage. These observations confirm that dislocation density governs hydrogen distribution and the prevailing HE mechanism, thus controlling the fracture mode in TWIP steels. |
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| ISSN: | 0264-1275 |