In this work hydrogen diffusion towards the fracture process zone is examined accounting for local hardening due to geometrically necessary dislocations (GNDs) by means of strain gradient plasticity (SGP). Finite element computations are performed within the finite deformation theory to characterize the gradient-enhanced stress elevation and subsequent diffusion of hydrogen towards the crack tip. Results reveal that GNDs, absent in conventional plasticity predictions, play a fundamental role on hydrogen transport ahead of a crack. SGP estimations provide a good agreement with experimental measurements of crack tip deformation and high levels of lattice hydrogen concentration are predicted within microns to the crack tip. The important implications of the results in the understanding of hydrogen embrittlement mechanisms are thoroughly discussed. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
机构:
LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China 100080LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China 100080
机构:
Tohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, JapanTohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, Japan
Yokobori, AT
Chinda, Y
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Tohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, JapanTohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, Japan
Chinda, Y
Nemoto, T
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Tohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, JapanTohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, Japan
Nemoto, T
Satoh, K
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Tohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, JapanTohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, Japan
Satoh, K
Yamada, T
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Tohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, JapanTohoku Univ, Fracture Res Inst, Fac Engn, Aoba Ku, Sendai, Miyagi 9808579, Japan