Hydrogen Embrittlement Susceptibility Research Articles

Study on hydrogen embrittlement susceptibility of X80 steel through in-situ gaseous hydrogen permeation and slow strain rate tensile tests

Hydrogen embrittlement is a serious threat to the safety operation for hydrogen blended natural gas pipelines. To determine the critical safety hydrogen blending ratio, in-situ high-pressure gaseous hydrogen permeation tests and slow strain rate tensile tests of X80 pipeline steel were conducted in the simulated hydrogen blended natural gas environments with 0–20 vol% hydrogen. The permeability characteristics, mechanical properties and fracture morphologies were systematically analyzed, and the embrittlement mechanism was discussed. Results show that the subsurface hydrogen concentration, ductility loss and hydrogen embrittlement susceptibility increased significantly as hydrogen blending ratio increased from 10% to 15%. Moreover, a positive correlation between subsurface hydrogen concentration and hydrogen embrittlement index was revealed. Combining the gaseous hydrogen permeation, SSRT results and fracture analysis, the 10% hydrogen blending ratio was determined as the conservative critical value for the safety operation of X80 hydrogen blended natural gas pipelines.

AURUBIS C12200 (Cu-DHP)

Abstract Aurubis C12200 (Cu-DHP) is a phosphorus-deoxidized copper, that contains a minimum of 99.9% copper and high residual phosphorus (0.015–0.040%). It is the most widely used copper for tube and pipe but also finds widespread use for sheet and strip items. Aurubis C12200 exhibits better ductility than Cu-ETP and is adaptable for progressive drawing operations requiring few or no intermediate anneals. A major advantage of Aurubis C12200 is the freedom from hydrogen embrittlement susceptibility in reducing atmospheres. This advantage is utilized in the cladding of steel and subsequent reducing atmosphere anneals without incurring the embrittlement, which occurs when cladding with Cu-ETP. The electrical and thermal conductivity are lower when compared with Cu-ETP but adequate for many applications as exemplified by a major use of strip to produce air conditioning and refrigeration tubing by gas shielding arc welding techniques. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and joining. Filing Code: Cu-934. Producer or source: Aurubis AG.

Assesment of ISL, SSRT and CLT techniques for quantification hydrogen embrittlement susceptibility of steels

Assesment of ISL, SSRT and CLT techniques for quantification hydrogen embrittlement susceptibility of steels

Stiffness-based method to identify the threshold load of low hardness steels using the Incremental step loading test

Hydrogen embrittlement (HE) is one of the main problems related to the use of metallic materials in sour or wet environments. The Incremental Step-Loading (ISL) test used to evaluate the susceptibility to HE of steels has gained more visibility over recent years, thus allowing for the determination of the threshold load (Pth) in H+ enriched environments. However, the ISL standard, ASTM F1624, limits the test to steels with a minimum hardness of 33 HRC. Even for those steels with 33 HRC, the results present some misinterpretations. In addition to this fact, one needs to consider that there are several applications where steels with hardness below 33 HRC are used, as for instance, in fasteners and tool joints under cathodic protection used in the oil and gas industry, for which hardness varies from 26 to 32 HRC. In light of the aforementioned, the standard limitation represents a major disadvantage related to the application of the ISL test. Grounded upon the said, the aim of the present study is to propose a methodology based on the specimen stiffness to be used in the ISL test results, allowing the Pth determination of steels with hardness lower than 33HRC. Conventional and extended ISL tests were performed in two steels (4137-M and 4130-M) with a 32HRC hardness values. Applying the stiffness-based method on the the conventional ISL test results, a threshold load (Pth) of 71.5 %PFFS and 66.0 %PFFS were found for the 4137-M and 4130-M steels, respectively. To validate these results, extended ISL tests were performed on both steels and the results showed a Pth of 73.7 %PFFS for the 4137-M steel and 66.0 %PFFS for the 4130-M steel. The results from the conventional ISL test, using the stiffness-based method proposed in this study, provided values similar or with differences lower than 5 %PFFS, when compared alongside the extended ISL tests. Moreover, ISL tests were performed on the same steels with 40 HRC hardness, and the AISI4137-M presented a Pth of 21.6 %PFFS and for 4130-M the Pth was 22.0 %PFFS. The main conclusion obtained from these tests was that, when large amount of plastic deformation is not present on ISL test, the load drop visual detection is sufficient to determine the Pth. As expected, it was observed that both steels with 40 HRC presented higher HE susceptibility than the 32 HRC ones. This behavior was due to higher stress concentration at the notch root presented by the higher hardness condition. The stiffness-based method proved to be robust and capable of separate yielding from hydrogen induced cracking of low hardness steels and could also be used to identify the Pth values of steels with hardness lower than that specified by the ASTM F1624 standard, and which are tested using the ISL test.

Strength-Toughness Balance and Hydrogen Embrittlement Susceptibility of a Precipitation-Strengthened Steel Adopted Tempering Process

Two steels with different nickel (Ni) content were investigated to reveal the role of Ni on strength-toughness balance and hydrogen embrittlement susceptibility. Although they were similar in microstructure, i.e., nano-particles were precipitated on martensitic laths, different mechanical behaviors were exhibited. After tempering, the yield strength of 3.5 Ni steel reached a peak at 500 °C, while that of 2.5 Ni steel kept a downward trend, indicating that precipitation strengthening was significant in 3.5 Ni steel. Combined with thermodynamic and kinetic analyses, it was shown that when the Ni content increased, the rich-copper (Cu) precipitation transformation driving force would be enhanced and the reverse of austenite transformation accelerated to improve its stability. Moreover, the increase of Ni content also induced the increase in high-angle grain boundaries (HAGBs), which could inhibit crack propagation. Under the comprehensive effects of strengthening and ductility mechanism, 3.5 Ni steel exhibited excellent cryogenic toughness. Although it was not possible to obtain the ideal balancing of strength-toughness for the steel with lower Ni content, its hydrogen embrittlement susceptibility is satisfying. The results showed that the increase of grain boundary density caused by the grain refinement of 2.5 Ni steel is the key factor for its lower hydrogen embrittlement sensitivity index. Moreover, with the reduction of Ni content, the decrease of HAGBs and the increase in Σ11 boundary were conducive to reducing hydrogen-assisted cracking, while the residual Fe3C in 3.5 Ni steel would deteriorate the hydrogen embrittlement resistance.

Hydrogen embrittlement behavior in interstitial Mn–N austenitic stainless steel

The susceptibility to hydrogen embrittlement behavior was investigated in an interstitial Mn–N austenitic steel HR183 and stainless steel 316L. Hydrogen was introduced by cathodic hydrogen charging at 363 K. HR183 has stronger austenite stability than 316L despite its lower nickel content, the addition of manganese and nitrogen inhibited martensitic transformation during the slow strain rate tensile deformation. Due to the diffusion of hydrogen being delayed by the interstitial solution of nitrogen atoms and the uniform dislocation slips, hydrogen permeates more slowly in HR183 than 316L, contributing to an 84.79 μm thinner brittle fracture layer in HR183 steel. Hydrogen charging caused elongation losses in both 316L and HR183 steels associated with the hydrogen-enhanced localized plasticity (HELP) and hydrogen-enhanced decohesion (HEDE) mechanism. However, the hydrogen embrittlement susceptibility of HR183 is 3.4 times lower than that of 316L according to the difference in elongation loss between the two steel after hydrogen charging. Deformation twins trapped a lot amount of hydrogen leading to brittle intergranular fracture in 316L. The multiple directions of slip in HR183 steel suppressed the strain localization inside grains and delayed the adverse effects conducted by HELP and HEDE mechanism, eventually inhibiting server hydrogen embrittlement in the HR183 steel. This study is assisting in the development of low-cost stainless steel with excellent hydrogen embrittlement resistance that can be used in harsh hydrogen-containing environments.

Hydraulic fracture behavior in the presence of hydrogen in notched miniature cylindrical specimens of a 42CrMo4 steel

The influence of internal hydrogen on the mechanical behavior of the 42CrMo4 steel grade has been evaluated by means of internal pressure fracture tests performed on hydrogen precharged notched cylindrical specimens. The notched cylindrical specimens were precharged in a 1 M H2SO4 solution + 0.25 g/l As2O3 for 3 h and 1.2 mA/cm2. Thereupon, hydraulic fracture tests were done under different ramps of pressure: 208, 100, 52, 35 and 25 MPa/h, respectively. Hydrogen content introduced into the notched cylindrical specimens (∼1 ppm) was determined by thermal desorption analysis (TDA), using a LECO DH 603 hydrogen analyser. Hydrogen damage was observed as testing time increased until 2 h. The burst pressure is reduced around 28 % while the Notch Mouth Opening Displacement decreased around 50 %. Hydrogen embrittlement susceptibility is discussed through the hydrogen embrittlement micromechanisms.

Hydrogen embrittlement susceptibility of dual-phase DP980 steel and its prevention with the help of coatings

ABSTRACTAHSS DP980 is widely used in automobiles and is susceptible to hydrogen embrittlement (HE), which negatively impacts the mechanical properties of the material. The aim of this work was to prevent the DP980 steel against the HE with the help of various surface coatings. Hydrogen charging of bare and various coated samples was accomplished by electrochemical reactions at a current density of 40 mA/cm2 for 24 hours. After charging, SSRT testing was performed at a strain rate of 10−5/s. Coating characterisation was completed by Coating Porosity Test, EDX and Microhardness test. Test results stated that the Ni-Cr and Gr ACS coating effectively reduces the hydrogen diffusion inside the material with improved mechanical properties, and the HE ratio decreases from 43.3% for the bare sample to 9.6% and 7.3% for those coated samples, respectively. The microhardness test also gave a high microhardness value for these coatings. Fracture surface examination shows that the bare hydrogen charged specimen failed in a mixed-mode manner, whereas all regions of Ni-Cr and Gr ACS-coated specimen fracture surface comprise dimple rupture.

Effect of post-processing heat treatment on hydrogen embrittlement susceptibility of API 5L X70 pipeline steel

Three different heat treatments were applied on X70 pipeline steel: below transformation temperature (X70-720), in the intercritical temperature range (X70-780), and in the intercritical temperature range + tempering (X70-780/720). Then, cathodic hydrogen charging was conducted on these heat-treated samples to study the effect of hydrogen ingress on the degradation of their mechanical properties in relation to their microstructural characteristics. The mechanical test results showed a reduction in elongation and toughness of all hydrogen-charged samples, as well as a strong correlation between hardness and hydrogen embrittlement (HE) susceptibility. However, the treatments, which resulted in the formation of cementite precipitates within the ferritic matrix (X70-780/720), showed improved resistance to HE. Also, the crystallographic texture analysis revealed that a high volume fraction ratio of {111} || ND to {100}<011> contributed to the significant improvement of HE resistance in X70-780/720, while a low volume fraction ratio resulted in the least HE resistance in X70-720 specimens.

Hydrogen gaseous embrittlement effect over mechanical properties of an experimental X-120 microalloyed steel subjected to heat treatments and different cooling rates

This research work aimed to determine the hydrogen gas pressure effect on the mechanical properties of an experimental X-120 microalloyed steel, subjected to heat treatments and quenched in different mediums. The steel in its as-received condition was reheated at 900 °C and quenched in spray water (900QSW), pressurized air (900QPA), and emulsion of water-oil medium (900QWO) which produces complex microstructures formed by martensite–bainite–acicular ferrite; otherwise, reheated at 820 °C and quenched in oil media (820QO) which produces a banded martensite-polygonal ferrite microstructure. To determine the hydrogen embrittlement susceptibility, in-situ tension tests were developed at 1, 4, and 7 MPa of hydrogen gas pressure. The results showed that as hydrogen gas pressure increases, the mechanical properties reduce in all quenched conditions, being the most susceptible condition the 820QO sample which presented the higher embrittlement index; on the contrary, the less susceptible condition was the 900QPA sample.

Studying the effect of multicomponent nano-coating alloy on hydrogen embrittlement of AISI 1018 steel by gas-phase process

The present study is attempted to investigate the influence of multicomponent Ni-alloy (BNi-2) on the hydrogen embrittlement (HE) behavior of AISI 1018 steel by using cathodic protection and tensile test. The results show that the HE indexes (HEI) decrease notably when AISI 1018 steel is coated with BNi-2 alloy by DC sputtering process. This coating processes leads to decrease in HE susceptibility of the AISI 1018 steel, which can be rationalized to the enhancement in corrosion resistance and the decrease in hydrogen absorption of the AISI 1018 steel after coating. The tensile strengths of bared samples were decreased with increasing charging time until 24 hours when stable at values 350 MPa. while the coated samples showed an increasement in the tensile strength from 570 MPa to 750 MPa. stabilization in strength at value of 600 MPa was observed after exceeding 48 hours. Also, the tensile test for uncoated specimens indicated a clear reduction on the modulus of elasticity compared with other coated ones.

Assessment of Hydrogen Embrittlement Susceptibility and Mechanism(s) in Quench and Tempered AISI 4135 Steel Using A Novel Fast Fracture Test in Bending

Assessment of Hydrogen Embrittlement Susceptibility and Mechanism(s) in Quench and Tempered AISI 4135 Steel Using A Novel Fast Fracture Test in Bending

A novel heat treatment for improving the hydrogen embrittlement resistance of a precipitation-hardened martensitic stainless steel

Application of the novel heat treatment significantly improves the PH13–8Mo steel hydrogen embrittlement (HE) resistance over that obtained by conventional heat treatment, while maintaining the mechanical properties. The mechanism of the proposed method is as follows: austenite captures hydrogen and the mechanical properties are improved by fine grain strengthening. The results of this study show that compared with the steel properties obtained by conventional peak-aged heat treatment, the novel heat treatment results in a reduction in the tensile strength from 1500 MPa to 1400 MPa, but a significant decrease in the HE susceptibility index (IHE) from 52% to 14%.

Influence of Plastic Deformation on the Hydrogen Embrittlement Susceptibility of Dual Phase Steels

The susceptibility of advanced high-strength steels (AHSS) to hydrogen embrittlement (HE) limits the broad utilization of these materials for body-in-white (BIW) components. The considerable decrease of both ductility and toughness due to local hydrogen accumulation inside of formed components may cause unpredictable time-delayed failure. In particular deep-drawn and punched AHSS components are prone to hydrogen absorption. This work investigates the influence of plastic deformation on hydrogen absorption of dual phase (DP) steels. For that purpose, tensile samples were machined out of three commercial 1.2 mm-thick DP sheets with ultimate tensile strengths of 626 MPa, 826 MPa and 1096 MPa. Samples were uniaxially pre-strained to 2 %, 5 %, 10 %, 15 % and 20 %. After pre-straining the samples were electrochemically charged with hydrogen, and the actual hydrogen contents were determined using a thermal desorption analyser (TDA). Before and after charging, the hardness of the samples was measured and the uniaxial quasi-static tensile properties were determined. In order to quantify the influence of plastic deformation on HE, slow strain rate tests (SSRT) were performed. The results of the tests were correlated with the fraction of martensite determined for each of the three steels.

The effect of Nb on the hydrogen embrittlement susceptibility of Q&P steel under static and dynamic loading

In the present study, the effect of Niobium (Nb) on the hydrogen embrittlement resistance of Quenched and Partitioning (Q&P) steel is investigated. For this purpose, the hydrogen uptake level and its impact on the mechanical properties of a Nb-free and a 0.024 wt% Nb Q&P steel are thoroughly analysed. The hydrogen trapping capacity is evaluated via thermal desorption spectroscopy (TDS). In-depth analysis of the desorption kinetics at different heating rates allows identification and quantification of the available trapping sites. The hydrogen embrittlement sensitivity of both steels is characterized using static and dynamic tensile tests. The addition of Nb results in an increase of the hydrogen concentration by more than 25%. The larger hydrogen content in the Nb steel, as a result of the higher fraction of grain boundaries/interphases, gives rise to a more severe embrittlement of the Nb steel compared to the Nb-free one. In addition to the larger hydrogen fraction in the Nb Q&P steel, the larger retained austenite fraction of low stability is detrimental due to the larger fraction of high carbon martensite formed when straining. This results in higher susceptibility to hydrogen embrittlement of the Nb microalloyed steel due to the brittle character of the high carbon martensite that forms easily during straining. Under dynamic loading conditions, the hydrogen embrittlement of both steels is minimal, which is attributed to a reduced hydrogen diffusion and the suppression of the transformation induced plasticity (TRIP) effect due to adiabatic heating.

The influence of phosphorus on the temper embrittlement and hydrogen embrittlement of some dual-phase steels

The temper embrittlement (TE) and hydrogen embrittlement (HE) of some dual-phase (DP) steels were investigated, focusing on the influence of the phosphorus (P) content. An increased P content of 0.02 wt% caused little TE and enhancement of HE susceptibility in DP steels. Hydrogen had little influence on strength, but caused a significant decrease in ductility. For the DP steels with the different microstructures, the hydrogen-induced cracks initiated at the specimen surface, and hydrogen-induced micro-crack initiation was mainly martensite related. The increased martensite related cracking and the tendency of interface cracking was attributed by the enhanced element segregation (by both increased tendency of P segregation and promoted by other element segregation like Mn). The increased P content can enhance HE susceptibility through both interface weakening related HE mechanisms (HESIV, HEDE, or defactant) and ferrite ductility loss related HELP mechanism.

Investigation for enhancing the resistance of H-induced delayed cracking for martensitic steel by quenching tempering and quenching partitioning: Influence of microstructure on hydrogen embrittlement and cracking behavior

The objective of the present study is to enhance the hydrogen embrittlement (HE) of the commercial martensitic steel (QT220). For this purpose, the heat treatments of quenching tempering and quenching partitioning are conducted, labeled as QT400 and Q&QP400, respectively. Compared to QT220, the mechanical properties of the both heat-treated specimens are reduced, nevertheless, the HE resistance is extremely promoted, resulting from the lesser dislocations, the more MoyCx, and the existence of the strained interface of cementite. Besides the above favorable factors, the presence of the ferrite is another important factor which contributes to the lowest HE susceptibility in Q&QP400, resulting from the propagation's inhibition of hydrogen induced cracks (HICs) by ferrite. The HICs behavior of QT220, QT400 and Q&QP400 are mainly influenced by the dislocation glide, the cementite at the high angle boundaries and ferrite, respectively, mainly resulting in the fractographs of quasi-cleavage, intergranular and finely fragmented quasi-cleavage, respectively. In addition, HICs always deflect when propagating to the RD//<112∼114> orientations, providing a valuable direction for research to enhance the HE resistance in the future.

Effect of Grain Orientation on Hydrogen Embrittlement Behavior of Interstitial-Free Steel

In interstitial-free (IF) steel with a certain microtexture, the micro-orientation of grains is essential to understand the occurrence of hydrogen-induced cracking in body-centered cubic (BCC) structural steels. In this study, the hydrogen embrittlement (HE) susceptibility of IF steels was determined by slow strain rate tensile (SSRT) tests and hydrogen microprinting (HMT) experiments from the perspective of crystal orientation. The strength of the specimen with hydrogen was slightly higher than that without hydrogen, while the ductility and toughness were drastically reduced by hydrogen charging during the SSRT test. The HE susceptibility was characterized by the loss of elongation (Iδ) and toughness (Iψ), with losses of 46.3% and 70%, respectively. The microstructural observations indicate that cracks initiated along grains oriented in the {100} || normal direction (ND), and grain boundaries (GBs) around {100}||ND were prone to be enriched in hydrogen atoms; that is, {100} || ND showed poor resistance to intergranular cracking and susceptible to hydrogen segregation. HMT was used to confirm the above viewpoints. Meanwhile, the statistical results showed those high-angle misorientations of 50–60° deviation are the locations most vulnerable to fracture.

Hydrogen trapping and hydrogen embrittlement in 15-5PH stainless steel

The hydrogen trapping capability and the effect on hydrogen embrittlement (HE) of Cu precipitations of the aged martensitic stainless steel were studied. The results shows that the hydrogen diffusion coefficient of specimens containing Cu precipitations reduced by an order of magnitude and the hydrogen content greatly increased. The peak-aged specimens (1 h) having the highest HE susceptibility was due to abundant hydrogen trapped by Cu precipitations coherent with matrix and escaped from the traps of Cu precipitations during tensile process. While Cu precipitations semi-coherent with matrix might have higher hydrogen trapping capability and reduce the HE sensitivity. Data AvailabilityThe raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

Investigation of carbide precipitates as hydrogen traps and their role in hydrogen embrittlement susceptibility of twinning-induced plasticity steel

ABSTRACT Solution and aging twinning-induced plasticity (TWIP) steel were obtained by the solution-treated at 1150°C for 2 h and aging-treated at 700°C for 6 and 24 h. Carbide precipitation is generated in the grain boundary and formed inside grains for aging time prolonging. Scanning Kelvin probe force microscopy was used to investigate the local distribution of hydrogen after hydrogen charging in TWIP steel with carbides in grain boundaries and grains. Results showed that carbides at the grain boundary adsorbed more hydrogen than those in the grain. Carbide precipitated phase as a hydrogen trap can enhance the resistance to hydrogen embrittlement and generated more secondary cracks at the grain boundary.