Analysis of hydrogen atom transport in a two-phase alloy

Turnbull, A.; Hutchings, R.

doi:10.1016/0921-5093(94)90488-x

Cited by 153 publications

(62 citation statements)

References 18 publications

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“…Retained austenite is able to act as a trap for three reasons, first that the solubility of hydrogen is greater in that phase, secondly the low rate at which hydrogen can diffuse in austenite, and thirdly, the γ /α interface is a strong trap 85) so that once the hydrogen enters the austenite, it is more difficult for it to leave. The ability of retained or reverted austenite to absorb excess hydrogen has been repeatedly demonstrated.…”

Section: Retained Austenite and Hydrogen Mobilitymentioning

confidence: 99%

Prevention of Hydrogen Embrittlement in Steels

2016

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The essential facts about the nature of the hydrogen embrittlement of steels have now been known for 140 years. It is diffusible hydrogen that is harmful to the toughness of iron. It follows, therefore, that the harmful influence of diffusible hydrogen can be mitigated by preventing its entry into steel or by rendering it immobile once it penetrates the material. This review deals with the methods that might be implemented to design steels and components that resist hydrogen embrittlement by reducing the intake of hydrogen or rendering it innocuous when it does penetrate the steel.

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Section: Retained Austenite and Hydrogen Mobilitymentioning

confidence: 99%

Prevention of Hydrogen Embrittlement in Steels

2016

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“…Moreover, in dual phase steels austenite also increases tortuosity of the hydrogen diffusion paths in the structure [25]. In nanobainitic steel, retained austenite surrounds the ferrite plates on all sides, thus it can easily close the diffusion path through the ferrite grains, and inhibit propagation of hydrogen induIn nanobainitic steel samples the grain size is small, and thus the surface area of intergranular boundaries, which are the hydrogen traps, is high [26]. According to the work of Rivera-Díaz-del-Castillo [28] the high density of hydrogen traps can immobilise the diffusive hydrogen in steel microstructure, and by this way led to a reduction of the embrittlement effects.…”

Section: Resultsmentioning

confidence: 99%

“…Steel 37CrMoV5-1 after austempering treatment contains about 55% of bainitic ferrite and 45% of retained austenite with small amount of martensite, so that it can be considered as a dual-phase steel. In previous works on hydrogen embrittlement of dual phase steels [7,10,25,26] it has been shown, that the diffusion coefficient of hydrogen in austenite is several orders of magnitude smaller than in the ferrite and the solubility of hydrogen -an order of magnitude larger than in ferrite. Thus, austenite can absorb much more hydrogen than ferrite.…”

Section: Resultsmentioning

confidence: 99%

Nanocrystalline Steels’ Resistance to Hydrogen Embrittlement

Skołek¹,

Marciniak²,

Skoczylas³

et al. 2015

Archives of Metallurgy and Materials

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The aim of this study is to determine the susceptibility to hydrogen embrittlement in X37CrMoV5-1 steel with two different microstructures: a nanocrystalline carbide-free bainite and tempered martensite. The nanobainitic structure was obtained by austempering at the bainitic transformation zone. It was found, that after hydrogen charging, both kinds of microstructure exhibit increased yield strength and strong decrease in ductility. It has been however shown that the resistance to hydrogen embrittlement of X37CrMoV5-1 steel with nanobainitic structure is higher as compared to the tempered martensite. After hydrogen charging the ductility of austempered steel is slightly higher than in case of quenched and tempered (Q&T) steel. This effect was interpreted as a result of phase composition formed after different heat treatments.Keywords: carbide-free bainite, tool steel, austempering, hydrogen embrittlement Celem pracy było określenie wrażliwości na kruchość wodorową stali X37CrMoV5-1 o dwóch różnych mikrostrukturach: nanokrystalicznego bainitu bezwęglikowego i odpuszczonego martenzytu. Struktura nanobainityczna została otrzymana w wyniku procesu hartowania izotermicznego w zakresie przemiany bainitycznej. Zaobserwowano, że po procesie katodowego nasycania wodorem oba typy mikrostruktury wykazują zwiększenie granicy plastyczności i znaczący spadek plastyczności. Wykazano jednak, że odporność na kruchość wodorową stali X37CrMoV5-1o strukturze nanobainitycznej jest lepsza w porównaniu do stali o strukturze martenzytu odpuszczonego. Po katodowym nasycaniu wodorem plastyczność stali hartowanej izotermicznie jest nieznacznie wyższa niż w przypadku stali hartowanej i odpuszczanej (Q&T). Zjawisko to zostało zinterpretowane jako wynik składu fazowego wytworzonego podczas różnych obróbek cieplnych.

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“…A susceptibilidade das ligas metálicas à degradação por hidrogênio depende, principalmente, da absorção de átomos de hidrogênio na fase metálica, da mobilidade destes átomos e da distribuição do hidrogênio entre a rede cristalina e os defeitos estruturais os quais agem como armadilhas; os dois últimos fatores estão diretamente relacionados com as características microestruturais do material [7]. A interação de hidrogênio com AID e AISD tem sido caracterizada usando a técnica de permeação eletroquímica de hidrogênio [1,6,8,9]. Foi determinado que a difusão de hidrogênio nestes aços ocorre principalmente através da fase ferrítica porque o coeficiente de difusão do hidrogênio nesta fase é muito maior (até cinco ordens de magnitude) do que o encontrado na austenita.…”

Section: Introductionunclassified

Estudo Da Difusão E Fragilização Por Hidrogênio Em Aço Inoxidável Superduplex

Ceballos¹,

Lage²,

Assis³

et al. 2017

Anais Do Congresso Anual Da ABM

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ResumoOs aços inoxidáveis duplex e superduplex são caracterizados por uma estrutura bifásica contendo ilhas de austenita precipitadas numa matriz de ferrita. Estes aços possuem boas propriedades mecânicas e boa resistência à corrosão. No entanto, estes aços podem apresentar fragilização por hidrogênio. No desenvolvimento deste trabalho se estudou a difusão e fragilização por hidrogênio de um aço inoxidável superduplex SAF 2507 nos estados como recebido e tratado térmicamente. Para avaliar a influência da microestrutura sobre a difusão do hidrogênio foram realizados ensaios de permeação electroquímica de hidrogênio. Observou-se que o coeficiente de difusão aparente aumenta em função da temperatura de recozimento. A influência de hidrogênio na resistência à fratura do material recozido a 1300°C foi estudada a partir de ensaios de tenacidade à fratura (CTOD). Determinou-se que a resistência à fratura do material diminui consideravelmente quando o mesmo é submetido a uma carga de hidrogênio. A presença de hidrogênio também modificou o mecanismo de fratura do material, observou-se uma fratura completamente dúctil no material que foi testado em ausência de hidrogênio e uma fratura frágil, caracterizada por clivagem, foi observada no material hidrogenado. Determinou-se que a fase austenítica pode ser fragilizada sob certas condições de carga de hidrogênio. Palavras-chave: Aços superduplex; Difusão de hidrogênio; Fragilização por hidrogênio; CTOD. STUDY OF HYDROGEN DIFUSSION AND EMBRITTLEMENT IN SUPER DUPLEX STAINLESS STEEL AbstractDuplex stainless steels are characterized by a biphasic structure containing austenite islands precipitated in the ferrite matrix. These steels have good mechanical properties and good corrosion resistance. However, these materials are susceptible to hydrogen embrittlement. In this work has been studied the hydrogen diffusion and embrittlement of super duplex stainless steel SAF 2507 in the material as received and annealed. To evaluate the influence of microstructure on the diffusion have been performed hydrogen electrochemical permeation tests. It was observed that the apparent diffusion coefficient increases with annealing temperature. The influence of hydrogen on toughness of the annealed material was studied using CTOD testing. It was determined that the fracture toughness of the material decreases considerably when it is subjected to hydrogen charge. The presence of hydrogen also changed the material fracture mechanism, a completely ductile fracture of the material has been observed in the material tested in the absence of hydrogen and a brittle fracture, characterized by cleavage, was observed in the hydrogenated material. It has been determined that the austenitic phase could be embrittle by hydrogen under certain conditions.

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Analysis of hydrogen atom transport in a two-phase alloy

Cited by 153 publications

References 18 publications

Prevention of Hydrogen Embrittlement in Steels

Prevention of Hydrogen Embrittlement in Steels

Nanocrystalline Steels’ Resistance to Hydrogen Embrittlement

Estudo Da Difusão E Fragilização Por Hidrogênio Em Aço Inoxidável Superduplex

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