Effect of hydrogen and stress concentration on the notch tensile strength of AISI 4135 steel

Wang, Maoqiu; Akiyama, Eiji; Tsuzaki, Kaneaki

doi:10.1016/j.msea.2005.03.008

Cited by 236 publications

(125 citation statements)

References 34 publications

(39 reference statements)

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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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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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“…[44][45][46][47][48][49]65) Slow strain rate test (SSRT) was performed using CNRB- The maximum value of HE measured after SSRT of exposed notched bar specimens was used as HE of B15, B13 and A13. The maximum HE of exposed bolt was used as HE of A11.…”

Section: B15 > B13 > A13 > A11mentioning

confidence: 99%

“…41) They also obtained critical NTS for delayed fracture by increasing applied stress in stepwise manner to obtain shape parameter in Weibull stress for evaluation of delayed fracture. 42 43) and the present authors [44][45][46][47][48][49] carried out slow strain rate test (SSRT) of hydrogen-precharged CNRBSs, and obtained the relationship between NTS and hydrogen content. For convenience and simplification, Hagihara et al proposed Conventional Strain Rate Test (CSRT) with a strain rate which is 2 orders of magnitude higher than that of SSRT.…”

Section: Introductionmentioning

confidence: 97%

Evaluation of Delayed Fracture Property of High Strength Bolt Steels

Akiyama

2012

ISIJ Int.

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Experimental studies attempting to evaluate the delayed fracture property of high strength bolt steels by using slow strain rate tests (SSRT) of circumferentially notched round bar specimens are reviewed in this paper. The relationship between the notch tensile strength (NTS) of the hydrogen-precharged specimens and the hydrogen content was approximated by power law relationship. It has been found that the local stress and the local diffusible hydrogen concentration control the occurrence of delayed fracture. To take into account the effect of hydrogen uptake from the environment, the notched bar specimens were subjected to cyclic corrosion test (CCT) and outdoor exposure, and their NTSs were measured using SSRT. The susceptibility of high strength steels to delayed fracture estimated from the decrease of NTS was correspondent to the fracture ratio of high strength bolts of the steels obtained by outdoor exposure tests, and was successfully evaluated with consideration of hydrogen uptake. Hydrogen entry behavior under CCT was monitored by electrochemical hydrogen permeation test, and continuous increase in hydrogen entry with growth of rust layer was observed. It is suggested that the "delay" of delayed fracture is the time required for the enhancement of the hydrogen entry efficiency.KEY WORDS: delayed fracture; hydrogen embrittlement; high strength steel; slow strain rate test; atmospheric corrosion; electrochemical hydrogen permeation; cyclic corrosion test; exposure test.

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“…From this logic, the local diffusible hydrogen concentration H* accumulated by stress-induced diffusion in this study was calculated using Eq. (2), 6) and results obtained from CLT, SSRT and CSRT were compared.…”

Section: Discussionmentioning

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%

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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Effect of hydrogen and stress concentration on the notch tensile strength of AISI 4135 steel

Cited by 236 publications

References 34 publications

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

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

Evaluation of Delayed Fracture Property of High Strength Bolt Steels

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

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