scholarly journals Hydrogen Embrittlement Evaluation of Micro Alloyed Steels by Means of J-Integral Curve

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1843 ◽  
Author(s):  
Marina Cabrini ◽  
Ennio Sinigaglia ◽  
Carlo Spinelli ◽  
Marco Tarenzi ◽  
Cristian Testa ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Slow Strain Rate ◽  
Slow Strain Rate Test ◽  
Integral Parameter ◽  
Hydrogen Effect ◽  
J Integral ◽  
Pipeline Steels

The aim of this work is the evaluation of the hydrogen effect on the J-integral parameter. It is well-known that the micro alloyed steels are affected by Hydrogen Embrittlement phenomena only when they are subjected at the same time to plastic deformation and hydrogen evolution at their surface. Previous works have pointed out the absence of Hydrogen Embrittlement effects on pipeline steels cathodically protected under static load conditions. On the contrary, in slow strain rate tests it is possible to observe the effect of the imposed potential and the strain rate on the hydrogen embrittlement steel behavior only after the necking of the specimens. J vs. Δa curves were measured on different pipeline steels in air and in aerated NaCl 3.5 g/L solution at free corrosion potential or under cathodic polarization at −1.05 and −2 V vs. SCE. The area under the J vs. Δa curves and the maximum crack propagation rate were taken into account. These parameters were compared with the ratio between the reduction of area in environment and in air obtained by slow strain rate test in the same environmental conditions and used to rank the different steels.

The study of hydrogen embrittlement of 12Cr2Mo1R(H) steel by slow strain rate test with in situ hydrogen charging

2019 ◽  
Vol 66 (5) ◽  
pp. 556-564
Author(s):  
Kun Zhang ◽  
Yicheng Fan ◽  
Xiaowei Luo ◽  
Xiaolang Chen ◽  
Chaolei Ban ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
Slow Strain Rate ◽  
Slow Strain Rate Test ◽  
Strain Rates ◽  
Content Type ◽  
Hydrogen Charging ◽  
Rate Test

Purpose 12Cr2Mo1R(H) steel is commonly used to make hot-wall hydrogenation reactors given its excellent mechanical properties and hydrogen embrittlement (HE) resistance. Longtime exposure to high-pressure hydrogen at medium temperature would still severely damage the mechanical properties of the Cr-Mo steel with surface HICs caused by hydrogen adsorption and hydrogen uptake. The mechanisms of HE remain controversial and have not been fully understood so far. Design/methodology/approach The HE of the steel was investigated by slow strain rate test at different strain rates with in situ hydrogen charging. The diffusion coefficient of hydrogen in the steel is measured by electrochemical technology of hydrogen permeation. HIC cracks of the fractured specimens were captured with field emission SEM equipped with an electron backscatter diffraction system. Findings Results showed that the hydrogen led to the plasticity of the samples reduced significantly, together with the distinct work hardening behavior induced by hydrogen charging during plastic flow stage. The fracture of in situ charged sample changes from quasi-cleavage to intergranular fracture with the decreasing of strain rates, which indicates that the steel become more susceptible to hydrogen. High densities of dislocations and deformation are found around the crack, where grains are highly sensitive to HIC. Grains with different Taylor factor are more susceptible to intergranular crack. Originality/value The results of the study would be helpful to a safer application of the steel.

An investigation of hydrogen embrittlement of 12Cr2Mo1R(H) steel by slow strain rate tests and first-principles calculation

2020 ◽  
Vol 67 (6) ◽  
pp. 545-555
Author(s):  
Qin Kang ◽  
Yicheng Fan ◽  
Kun Zhang ◽  
Xiaolang Chen ◽  
Hongyu San ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
First Principles ◽  
Slow Strain Rate ◽  
First Principles Calculation ◽  
Hydrogen Effect ◽  
Medium Temperature ◽  
Cross Sectional ◽  
Content Type

Purpose With excellent mechanic properties and hydrogen embrittlement (HE) resistance, 12Cr2Mo1R(H) steel is suitable to make hot-wall hydrogenation reactors. However, longtime exposure to a harsh environment of high-pressure hydrogen at medium temperature in practical application would still induce severe hydrogen uptake and eventually damage the mechanical properties of the steel. The study aims to evaluate the HE resistance of the steel under different tensile strain rates after hydrogen charging and analyze the hydrogen effect from atomic level. Design/methodology/approach This research studied the HE properties of 12Cr2Mo1R(H) steel by slow strain rate tests. Meanwhile, the effect of hydrogen on the structures and the mechanical properties of the simplified models of the steel was also investigated by first-principle calculations. Findings Experimental results showed that after hydrogen pre-charging in this work, hydrogen had little effect on the microstructure of the steel. The elongations and reduction of cross-sectional area of the samples reduced a lot, by contrast, the yield and tensile strengths changed slightly. The 12Cr2Mo1R(H) steel was not very susceptible to HE with a maximum embrittlement index of about 20.00%. First principles calculation results showed that after H dissolution, lattice distortion occurred and interstitial H atoms would preferentially occupy the tetrahedral interstitial site in bcc-Fe crystal and increase the stability of the supercells. With the increase of H atoms added into the simplified model, the steel still possessed a good ductility and toughness at a low hydrogen concentration, while the material would become brittle as the concentration of hydrogen continued to increase. Originality/value These finds can provide valuable information for subsequent HE studies on this steel.

Hydrogen Embrittlement of Low Carbon HSLA Steel during Slow Strain Rate Test

2011 ◽  
Vol 197-198 ◽  
pp. 642-645
Author(s):  
Jing Wei Zhao ◽  
Young Soo Chun ◽  
Chong Soo Lee
Keyword(s):  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
Hydrogen Content ◽  
Hsla Steel ◽  
Peak Stress ◽  
Slow Strain Rate ◽  
Slow Strain Rate Test ◽  
Low Carbon ◽  
Diffusible Hydrogen ◽  
Rate Test

The hydrogen embrittlement of a low carbon HSLA steel has been investigated by means of slow strain rate test (SSRT) on circumferentially notched specimens. Hydrogen was introduced into specimens by electrochemical charging and the diffusible hydrogen content was measured by thermal desorption spectrometry (TDS) analysis. The activation energy of hydrogen desorption in the present steel was calculated to be 12.75 kJ/mol after TDS analysis. The peak stress and displacement during notch tensile tests had been found to decrease simultaneously with diffusible hydrogen content, which could be expressed by two power law relationships, respectively. Fracture surface was a cleavage type indicating that the steel had high susceptibility of hydrogen embrittlement.

scholarly journals Stress Corrosion Cracking of Additively Manufactured Alloy 625

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6115
Author(s):  
Marina Cabrini ◽  
Sergio Lorenzi ◽  
Cristian Testa ◽  
Francesco Carugo ◽  
Tommaso Pastore ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
High Strain ◽  
Corrosion Cracking ◽  
Slow Strain Rate ◽  
Laser Source ◽  
Alloy 625

Laser bed powder fusion (LPBF) is an additive manufacturing technology for the fabrication of semi-finished components directly from computer-aided design modelling, through melting and consolidation, layer upon layer, of a metallic powder, with a laser source. This manufacturing technique is particularly indicated for poor machinable alloys, such as Alloy 625. However, the unique microstructure generated could modify the resistance of the alloy to environment assisted cracking. The aim of this work was to analyze the stress corrosion cracking (SCC) and hydrogen embrittlement resistance behavior of Alloy 625 obtained by LPBF, both in as-built condition and after a standard heat treatment (grade 1). U-bend testing performed in boiling magnesium chloride at 155 and 170 °C confirmed the immunity of the alloy to SCC. However, slow strain rate tests in simulated ocean water on cathodically polarized specimens highlighted the possibility of the occurrence of hydrogen embrittlement in a specific range of strain rate and cathodic polarization. The very fine grain size and dislocation density of the thermally untreated specimens appeared to increase the hydrogen diffusion and embrittlement effect on pre-charged specimens that were deformed at the high strain rate. Conversely, heat treatment appeared to mitigate hydrogen embrittlement at high strain rates, however at the slow strain rate all the specimens showed a similar behavior.

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

2020 ◽  
Vol 163 ◽  
pp. 108291 ◽  
Author(s):  
Emilio Martínez-Pañeda ◽  
Zachary D. Harris ◽  
Sandra Fuentes-Alonso ◽  
John R. Scully ◽  
James T. Burns
Keyword(s):  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
Tensile Testing ◽  
Slow Strain Rate

Corrosion Fatigue Mechanisms and Fracture Mechanics Based Modelling for Subsea Pipeline Steels

2017 ◽  
Author(s):  
Ankang Cheng ◽  
Nian-Zhong Chen
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Corrosion Fatigue ◽  
Fatigue Cracking ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Propagation Time ◽  
Loading Frequency ◽  
Pipeline Steels ◽  
Driving Mechanisms

Subsea structures such as pipelines are vulnerable to environment-assisted crackings (EACs). As a type of EAC, corrosion fatigue (CF) is almost inevitable. For such a process, stress corrosion (SC) and hydrogen-assisted cracking (HAC) are the two mainly driving mechanisms. And it was further pointed out that slip dissolution (SD) and hydrogen embrittlement (HE) should be responsible for SC and HAC respectively. Based on such a fact, a two-component physical model for estimating the CF crack propagation rate was proposed. The proposed model was built in a frame of fracture mechanics integrated with a dissolution model for C-Mn steel and a newly established model by the authors accounting for the influence from HE upon crack propagation. The overall CF crack propagation rate is the aggregate of the two rates predicted by the two sub-individual models, and then the crack propagation time is calculated accordingly. The model has been proven to be capable of capturing the features of HE influenced fatigue cracking behaviour as well as taking mechanical factors such as the loading frequency and stress ratio into account by comparison with the experimental data of X42 and X65 pipeline steels.

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