Effect of grain refinement on hydrogen embrittlement behaviors of high-Mn TWIP steel

Bai, Yu; Momotani, Yuji; Chen, M.C.; Shibata, Akinobu; Tsuji, Nobuhiro

doi:10.1016/j.msea.2015.11.017

Cited by 121 publications

(43 citation statements)

References 20 publications

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“…3-5) indicate that the nucleation and growth of voids on loading can be accelerated by an increase of the coverage of H atoms on the GB. This agrees with the experimental result that suppression of hydrogen embrittlement can be induced by a refinement of the grain size of the material for which the coverage of H atoms on GB is reduced under the same hydrogen charging condition (Bai et al, 2016). For the gathering of H atoms in the material, one particular case is the gathering of H atoms at the crack tip due to the stress concentration at the mode I crack loading (Song and Curtin, 2013).…”

Section: Discussionsupporting

confidence: 89%

Hydrogen embrittlement controlled by reaction of dislocation with grain boundary in alpha-iron

Wan

Geng

Ishii

et al. 2019

International Journal of Plasticity

100

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Hydrogen atoms absorbed by metals in hydrogen-containing environments can lead to the premature fracture of the metal components used in load-bearing conditions. Since metals used in practice are mostly polycrystalline, grain boundaries (GBs) can play an important role in hydrogen embrittlement of metals. Here we show that the reaction of GBs with lattice dislocations is a key component in hydrogen embrittlement mechanism for polycrystalline metals. We use atomistic modeling methods to investigate the mechanical response of GBs in alpha-iron with various hydrogen concentrations.Analysis indicates that dislocations impingement and emission on the GB can provoke it to locally transform into an activated state with a more disordered atomistic structure, and introduce a local stress concentration. The activation of the GB segregated with hydrogen atoms can greatly facilitate decohesion of the GB. We propose a hydrogen embrittlement model that can give better explanation of many experimental observations.

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Section: Discussionsupporting

confidence: 89%

Hydrogen embrittlement controlled by reaction of dislocation with grain boundary in alpha-iron

Wan

Geng

Ishii

et al. 2019

International Journal of Plasticity

100

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“…After making this connection between GB character and local Young's modulus, we needed to relate the GB distribution to the hydrogen-induced failure of the specimens. We referred to [42], where the distribution of low and high angle grain boundaries was reported for TWIP steels, depending on the average grain size. Only for the UFG case, low angle grain boundaries, did we expect from our considerations to support precipitation of hydrogen-rich phases and not be suppressed.…”

Section: Thermodynamic Assessmentmentioning

confidence: 99%

Influence of Microstructural Morphology on Hydrogen Embrittlement in a Medium-Mn Steel Fe-12Mn-3Al-0.05C

Shen

Song

Sevsek

et al. 2019

Metals

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The ultrafine-grained (UFG) duplex microstructure of medium-Mn steel consists of a considerable amount of austenite and ferrite/martensite, achieving an extraordinary balance of mechanical properties and alloying cost. In the present work, two heat treatment routes were performed on a cold-rolled medium-Mn steel Fe-12Mn-3Al-0.05C (wt.%) to achieve comparable mechanical properties with different microstructural morphologies. One heat treatment was merely austenite-reverted-transformation (ART) annealing and the other one was a successive combination of austenitization (AUS) and ART annealing. The distinct responses to hydrogen ingression were characterized and discussed. The UFG martensite colonies produced by the AUS + ART process were found to be detrimental to ductility regardless of the amount of hydrogen, which is likely attributed to the reduced lattice bonding strength according to the H-enhanced decohesion (HEDE) mechanism. With an increase in the hydrogen amount, the mixed microstructure (granular + lamellar) in the ART specimen revealed a clear embrittlement transition with the possible contribution of HEDE and H-enhanced localized plasticity (HELP) mechanisms.

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“…The PAG refinement in Nb2-A steel resulted in an increasing fraction of PAGBs. Considering the similar hydrogen contents in Nb0-A and Nb2-A steels, the increasing PAGB fraction gave rise to the reduction of hydrogen concentration per unit surface of boundaries 16 . Such an alleviated hydrogen concentration delayed the HE fracture of Nb2-A steel.…”

Section: Resultsmentioning

confidence: 98%

Effect of undissolved Nb carbides on mechanical properties of hydrogen-precharged tempered martensitic steel

Seo

Kim

et al. 2020

Sci Rep

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Nb carbides have attracted significant attention to enhance the resistance of tempered martensitic (TM) steel to hydrogen embrittlement (HE). However, previous studies have elucidated the role of Nb carbides in HE resistance without categorizing their types (i.e., undissolved and newly precipitated). This study focuses on the effect of "undissolved" Nb carbides on the tensile and fatigue properties of hydrogen-precharged TM steels. It validated the following two factors for the HE resistance of the TM steels containing undissolved Nb carbides: hydrogen-trapping by the carbides and refinement of prior austenite grain. The former factor rarely affected the HE resistance owing to the interfacial incoherency between the undissolved carbides and ferritic matrix. Such results are distinguished from previous studies focusing on the newly precipitated carbides. In contrast, the latter factor contributed significantly to the HE resistance via the decrease in hydrogen contents per unit surface of prior austenite grain boundaries. Hydrogen embrittlement (HE) indicates the deterioration in mechanical properties owing to hydrogen atoms inside a ferrous alloy 1,2. HE is particularly important for the use of high-strength steels, such as a tempered martensitic (TM) steel. The TM structure can yield a high strength that exceeds 1.2 GPa after a simple heat treatment, rendering this steel important for various industries. Nevertheless, a high density of defects in the TM structure renders it highly vulnerable to HE 3. Consequently, this has resulted in increasing demands for an enhanced HE resistance of TM steels. The addition of Nb is an effective approach to increase the HE resistance of TM steels. It has been reported that HE resistance increases owing to the hydrogen trapping by Nb carbides and the refinement of prior austenite grains (PAGs). Such factors hindered the diffusion and concentration of the hydrogen present inside materials 4. A recent study 5 suggested a different mechanism for achieving an improvement in HE resistance, wherein Nb addition decreased the Σ3 boundary fraction in lath martensites. However, previous studies have primarily investigated Nb carbides, which are newly precipitated during a tempering process. The other type of Nb carbides (i.e., "undissolved" carbides) has attracted significantly less attention despite the fact that their resultant amounts are not negligibly small. Therefore, the effect of undissolved Nb carbides on the HE resistance of TM steels was investigated in this study. Four hydrogen-precharged TM steels were evaluated under uniaxial and cyclic loading conditions by considering the application environment of the material.

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Effect of grain refinement on hydrogen embrittlement behaviors of high-Mn TWIP steel

Cited by 121 publications

References 20 publications

Hydrogen embrittlement controlled by reaction of dislocation with grain boundary in alpha-iron

Hydrogen embrittlement controlled by reaction of dislocation with grain boundary in alpha-iron

Influence of Microstructural Morphology on Hydrogen Embrittlement in a Medium-Mn Steel Fe-12Mn-3Al-0.05C

Effect of undissolved Nb carbides on mechanical properties of hydrogen-precharged tempered martensitic steel

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