A uniform hydrogen degradation law for high strength steels

The onset of sub-critical crack growth during slow strain rate tensile testing (SSRT) is assessed through a combined experimental and modeling approach. A systematic comparison of the extent of intergranular fracture and expected hydrogen ingress suggests that hydrogen diffusion alone is insufficient to explain the intergranular fracture depths observed after SSRT experiments in a Ni-Cu superalloy. Simulations of these experiments using a new phase field formulation indicate that crack initiation occurs as low as 40% of the time to failure. The implications of such sub-critical crack growth on the validity and interpretation of SSRT metrics are then explored.

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“…No plastic-damage coupling is typically defined in similar fracture models, such as cohesive zone approaches (see, for example, Refs. [72,73]).…”

Section: Phase Field Fracture Of Embrittled Elastic-plastic Solidsmentioning

confidence: 99%

On the suitability of slow strain rate tensile testing for assessing hydrogen embrittlement susceptibility

et al. 2020

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“…Such scheme leads to accurate results if the viscosity coefficient, ξ, is sufficiently small [4]. A sensitivity study has been conducted in the few cases where viscous regularization was needed; values of ξ on the order of 10 −6 have proven to be appropriate for the boundary value problem under consideration.…”

Section: Cohesive Zone Modelmentioning

confidence: 99%

“…The use of cohesive zone formulations is particularly appealing in this regard, as they constitute a suitable tool to characterize the sensitivity of the fracture energy to hydrogen coverage. The cohesive traction separation law can be derived from first principles quantum mechanics [2] or calibrated with experiments [3,4]. The statistical distribution of relevant microstructural features has also fostered the use of weakest-link approaches [5,6].…”

Section: Introductionmentioning

confidence: 99%

A cohesive zone framework for environmentally assisted fatigue

Busto

Betegón

Martínez‐Pañeda

2017

Engineering Fracture Mechanics

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“…This is also supported by the KAM observations discussed above. In this sense, the HDL of Yu et al [38] is acceptable.…”

Section: --mentioning

confidence: 88%

“…The effects of HE can be incorporated into the CZM procedure by lowering the value of c with increasing hydrogen concentration while keeping c constant [37] c is described with a hydrogen degradation law (HDL), which plays a fundamental part in capturing the HE phenomena. Recently, Yu et al [38] calibrated a CZM-based uniform HDL for an engineering size scale from notched tensile tests using quenched and tempered AISI 4135 steel c,H=0 is the hydrogen free critical cohesive stress and C L the lattice hydrogen concentration.…”

mentioning

confidence: 99%

Fracture toughness of hydrogen charged as-quenched ultra-high-strength steels at low temperatures

Pallaspuro

Kisko

et al. 2017

Materials Science and Engineering: A

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The effect of hydrogen on the fracture and impact toughness of ultra-high-strength steels at sub-zero temperatures in the transition temperature region has been investigated with arctic applications in mind. Two types of as-quenched microstructure were studied, i.e. autotempered martensite and a mixture of martensite and bainite, both having yield strengths close to 1000 MPa. These were charged with hydrogen using passive cathodic protection and then tested in both the charged and uncharged condition at sub-zero temperatures. Hydrogen contents were measured with meltextraction. Fractography, kernel average misorientation measurements and cohesive zone modelling were used to analyse the results considering the degree and the active mechanisms of hydrogen embrittlement. It is shown that hydrogen embrittlement is present at sub-zero temperatures, causing an increase in fracture toughness reference temperature T 0 and a small decrease in deformation capability. The relationship between the T 0 and the impact toughness transition temperature T 28J , which, in the case of ultra-high-strength steel, deviates from that observed for lower strength steels, is proposed to be affected by the hydrogen content.

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A uniform hydrogen degradation law for high strength steels

Cited by 64 publications

References 66 publications

On the suitability of slow strain rate tensile testing for assessing hydrogen embrittlement susceptibility

On the suitability of slow strain rate tensile testing for assessing hydrogen embrittlement susceptibility

A cohesive zone framework for environmentally assisted fatigue

Fracture toughness of hydrogen charged as-quenched ultra-high-strength steels at low temperatures

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