Evaluation of Delayed Fracture Characteristics of High Strength Steel based on CSRT Method

Hagihara, Yukito; Ito, Chikahito; Hisamori, Noriyuki; Suzuki, Hiroshi; Takai, Kenichi; Akiyama, Eiji

doi:10.2355/tetsutohagane.94.215

Cited by 74 publications

(46 citation statements)

References 5 publications

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“…The TDA results of Steel S11 with cathodic electrolysis hydrogen charging showed that the peak temperature of the hydrogen desorption curve was about 100°C, which was equivalent to that in previous studies 13,14) on similar SCM steels with tensile strengths of 1 300 MPa and 1 500 MPa. As shown in Fig.…”

Section: Hydrogen Absorbing Behaviorsupporting

confidence: 50%

“…It has been reported by Hagihara et al 13,14) that SSRT and CSRT presented almost the same relationship between the local stress and the local diffusible hydrogen concentration at the initiation site for 1 300-1 500 MPa grade steels. From this logic, the local diffusible hydrogen concentration H* accumulated by stress-induced diffusion in this study was calculated using Eq.…”

Section: Discussionmentioning

confidence: 93%

“…In contrast, CSRT [13][14][15][16] is performed under a high strain rate similar to ordinary tensile testing rate which makes the stress-induced diffusion negligible. Therefore, hydrogen content at the crack initiation site of hydrogen embrittlement in the vicinity of the notch root is equivalent to the average hydrogen content in the specimen.…”

Section: Conventional Strain Rate Test (Csrt)mentioning

confidence: 99%

“…Recently, susceptibility to delayed fracture is evaluated by Slow Strain Rate Test (SSRT) [6][7][8][9][10][11][12] and Conventional Strain Rate Test (CSRT) [13][14][15][16] which can complete the delayed fracture test in a shorter time than CLT. The relationship between H C and fracture stress can be obtained by SSRT and CSRT.…”

Section: )mentioning

confidence: 99%

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Comparison of Constant Load, SSRT and CSRT Methods for Hydrogen Embrittlement Evaluation Using Round Bar Specimens of High Strength Steels

et al. 2016

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Resistance to hydrogen embrittlement of low alloy steels was evaluated based on their critical hydrogen content and critical stress. Constant load test (CLT), Slow Strain Rate Test (SSRT) and Conventional Strain Rate Test (CSRT) were carried out using JIS-SCM435 and V-added steels in six laboratories. It was confirmed that the same test results were obtained in different laboratories under the same test conditions. Furthermore, the relationships between diffusible hydrogen content and nominal fracture stress obtained by means of CLT and SSRT were similar to each other. In CSRT, the nominal fracture stress was higher than that in CLT and SSRT under the same absorbed hydrogen content in the specimens. In SSRT and CSRT, fracture surfaces showed Quasi-cleavage mode under small hydrogen content, while they showed Inter-granular fracture under large hydrogen content. In order to compare the three methods considering the concentration of hydrogen in stress field, locally accumulated hydrogen content under the same fracture stress is calculated. The locally accumulated hydrogen under the same applied stress, in other words, critical hydrogen content to hydrogen embrittlement, is the following order; SSRT < CLT < CSRT in JIS-SCM435, and CSRT < CLT ≒ SSRT in V-added steels.

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Section: Hydrogen Absorbing Behaviorsupporting

confidence: 50%

Section: Discussionmentioning

confidence: 93%

Section: Conventional Strain Rate Test (Csrt)mentioning

confidence: 99%

Section: )mentioning

confidence: 99%

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Comparison of Constant Load, SSRT and CSRT Methods for Hydrogen Embrittlement Evaluation Using Round Bar Specimens of High Strength Steels

et al. 2016

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“…The Constant Loading Test (CLT), 22,23) Slow Strain Rate Technique (SSRT) 24) and Conventional Strain Rate Test (CSRT), [25][26][27] which are major evaluation methods in the field of UHSS bolts, have been minor methods in the field of UHSS sheets. Presumably, these methods are not widely used with UHSS sheets because only uniaxial deformation test can be conducted by those methods and it is more difficult to predict the risk of hydrogen embrittlement fracture in actual parts with considering the influence of forming modes.…”

Section: Methods Of Evaluating Hydrogen Embrittlement Resistance Of Amentioning

confidence: 99%

Hydrogen Embrittlement Resistance Evaluation of Ultra High Strength Steel Sheets for Automobiles

Takagi¹,

Toji²,

Yoshino³

et al. 2012

ISIJ Int.

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When ultra high strength steel (UHSS) sheets with tensile strength over 980 MPa are applied in automobiles, there is a risk that a type of hydrogen embrittlement fracture called delayed fracture may occur while a vehicle is in use. This paper summarizes the effects of stress, strain, diffusible hydrogen content and the forming mode on the hydrogen embrittlement resistance of UHSS sheets for automotive applications. In this study, 1 180 MPa grade ferrite-martensite dual phase steel was used. This material was evaluated by the U-bending and drawn cup methods. It was concluded that high strain, high stress and high diffusible hydrogen content reduced hydrogen embrittlement resistance.In addition, an improved immersion-type hydrogen charging method using an ammonium thiocyanate (NH4SCN) aqueous solution was introduced in this paper. The NH4SCN solution enables control of the diffusible hydrogen content from low to high concentrations using the NH4SCN concentration, and dissolution of the specimens during immersion in NH4SCN was minimal, making it possible to maintain substantially the same surface condition as before immersion.KEY WORDS: delayed fracture; equivalent strain; equivalent stress; diffusible hydrogen; U-bending; drawn cup; ammonium thiocyanate; immersion-type hydrogen charging method.

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Analysis and Evaluation

Fujita¹,

Takagi²,

Akimune³

2023

Springer Series in Materials Science

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Evaluation of Delayed Fracture Characteristics of High Strength Steel based on CSRT Method

Cited by 74 publications

References 5 publications

Comparison of Constant Load, SSRT and CSRT Methods for Hydrogen Embrittlement Evaluation Using Round Bar Specimens of High Strength Steels

Comparison of Constant Load, SSRT and CSRT Methods for Hydrogen Embrittlement Evaluation Using Round Bar Specimens of High Strength Steels

Hydrogen Embrittlement Resistance Evaluation of Ultra High Strength Steel Sheets for Automobiles

Analysis and Evaluation

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