Ultrasonic nanocrystal surface modification for strength improvement and suppression of hydrogen permeation in multi-layered steel

•The surface microstructure of multi-layered steel was modified using ultrasonic nanocrystal surface modification (UNSM).•The roles of UNSM-treated surface layers in strength and hydrogen permeation behavior were investigated.•The yield strength improved via synergetic contributions of the grain ref...

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Bibliographic Details
Published in:Journal of alloys and compounds 2021-12, Vol.885, p.160975, Article 160975
Main Authors: Jo, Min Cheol, Yoo, Jisung, Amanov, Auezhan, Song, Taejin, Kim, Sang-Heon, Sohn, Seok Su, Lee, Sunghak
Format: Article
Language:English
Subjects:
Compressive properties
Dislocations
Grain boundaries
Grain refinement
Hydrogen
Hydrogen embrittlement
Hydrogen permeation
Microstructural evolution
Microstructure
Multi-layered steel (MLS)
Multilayers
Nanocrystals
Penetration
Residual stress
Steel
Surface layers
Tensile properties
Twin boundaries
Ultrasonic nanocrystal surface modification (UNSM)
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Summary:•The surface microstructure of multi-layered steel was modified using ultrasonic nanocrystal surface modification (UNSM).•The roles of UNSM-treated surface layers in strength and hydrogen permeation behavior were investigated.•The yield strength improved via synergetic contributions of the grain refinement effect and dislocation strengthening.•The UNSM-affected zone of 150–210 µm along depth direction effectively suppressed the hydrogen permeation. [Display omitted] Hydrogen embrittlement of multi-layered steel (MLS) is significantly affected by a degree of hydrogen permeation from surface layers to interfaces. Here, the surface microstructure of multi-layered steel was modified for the first time using ultrasonic nanocrystal surface modification (UNSM), and the roles of UNSM-treated surface layers in strength and hydrogen permeation behavior were investigated by examining microstructural evolutions of the surface layer. Since the UNSM induced the compressive residual stress, grain refinement, and deformation twin formation at the specimen surface, the yield strength greatly improved via synergetic contributions of the grain refinement effect and dislocation strengthening. In addition, the UNSM-affected zone of 150–210 µm along depth direction effectively suppressed the hydrogen permeation by supplying compressive residual stresses and hydrogen trapping sites including grain boundaries, dislocations, and twin boundaries.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2021.160975