Nitriding of the surface in martensitic stainless steels is commonly carried out to improve their wear resistance. The process of plasma nitriding in stainless steel is influenced by two mechanisms: physical diffusion...Nitriding of the surface in martensitic stainless steels is commonly carried out to improve their wear resistance. The process of plasma nitriding in stainless steel is influenced by two mechanisms: physical diffusion through the surface and chemical gas-metal reaction. The inner nitriding interaction involves the simultaneous penetration and formation of a solid solution, as well as the interaction of nitrogen with specific alloying elements, resulting in the development of homogeneous and heterogeneous structures. Our study concludes that the observed intergranular hydrogen embrittlement and crack formation during the surface nitridation process of AMS 5719 martensite alloy steel can be attributed to the ammonium concentration of approximately 50% at a temperature of 530˚C.展开更多
This study investigated the susceptibility of X80 pipeline steel to hydrogen embrittlement given different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles in H2S environment.The fractur...This study investigated the susceptibility of X80 pipeline steel to hydrogen embrittlement given different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles in H2S environment.The fracture strain of the steel samples decreased with increasing hydrogen pre-charging time;this steel degradation could almost be recovered after diffusible hydrogen was removed when the hydrogen pre-charging time was<8 d.However,unrecoverable degeneration occurred when the hydrogen pre-charging time extended to 16–30 d.Moreover,nanovoid formation meant that the hydrogen damage to the steel under intermittent hydrogen pre-charging–releasing–recharging conditions was more serious than that under continuous hydrogen pre-charging conditions.This study illustrated that the mechanical degradation of steel is inevitable in an H2S environment even if diffusible hydrogen is removed or visible hydrogen-induced cracking is neglected.Furthermore,the steel samples showed premature fractures and exhibited a hydrogen fatigue effect because the repeated entry and release of diffusible hydrogen promoted the formation of vacancies that aggregated into nanovoids.Our results provide valuable information on the mechanical degradation of steel in an H2S environment,regarding the change rules of steel mechanical properties under different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles.展开更多
We investigated the critical influence of in-situ nanoparticles on the mechanical properties and hydrogen embrittlement(HE)of high-strength steel.The results reveal that the mechanical strength and elongation of quenc...We investigated the critical influence of in-situ nanoparticles on the mechanical properties and hydrogen embrittlement(HE)of high-strength steel.The results reveal that the mechanical strength and elongation of quenched and tempered steel(919 MPa yield strength,17.11%elongation)are greater than those of hot-rolled steel(690 MPa yield strength,16.81%elongation)due to the strengthening effect of insitu Ti_(3)O_(5)–Nb(C,N)nanoparticles.In addition,the HE susceptibility is substantially mitigated to 55.52%,approximately 30%lower than that of steels without in-situ nanoparticles(84.04%),which we attribute to the heterogeneous nucleation of the Ti_(3)O_5 nanoparticles increasing the density of the carbides.Compared with hard TiN inclusions,the spherical and soft Al_(2)O_(3)–MnS core–shell inclusions that nucleate on in-situ Al_(2)O_(3) particles could also suppress HE.In-situ nanoparticles generated by the regional trace-element supply have strong potential for the development of high-strength and hydrogen-resistant steels.展开更多
An electronic approach to the mechanism of hydrogen embrittlement in metals is pre-sented and discussed. Some problems of the mechanism of hydrogen embrittlement are pointed out from an electronic point of view. Elect...An electronic approach to the mechanism of hydrogen embrittlement in metals is pre-sented and discussed. Some problems of the mechanism of hydrogen embrittlement are pointed out from an electronic point of view. Electronic structure calculations in a periodically cleaved or slipped lattice are developed in orker to identofy deformation-sensitive electronic states in the absence of hydrogen. The calculational results are given and discussed for a trunsition metal, Pd. Electronic structure calculations in the presence of hydrogen are outlined and hydrogen embrittlement in transition metals is discussed in terms of electronic states.展开更多
Bidirectional electromigration rehabilitation(BIEM)is a novel electrochemical rehabilitation method involving the injection of inhibitors into steel bar surface.The BIEM effect and hydrogen embrittlement(HE)risk depen...Bidirectional electromigration rehabilitation(BIEM)is a novel electrochemical rehabilitation method involving the injection of inhibitors into steel bar surface.The BIEM effect and hydrogen embrittlement(HE)risk depend on the electrochemical parameters(current density and duration)and operating condition(stress level and concrete cover thickness)of reinforced concrete structures.Experiments were performed in this study to investigate the relationships between the aforementioned factors.For a small current density group,a linear relationship was established between electric flux and chloride extraction.For a large current density group,the reasonable current density,stress level,and treatment time were obtained.Finally,the querying method of electrochemical parameters combined with treatment time and current density was proposed.展开更多
The effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 was investigated by conducting notch tensile tests. Notch tensile specimens with various precipitation morphologies of δ phase were...The effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 was investigated by conducting notch tensile tests. Notch tensile specimens with various precipitation morphologies of δ phase were prepared with different heat treatments, and hydrogen was charged into the tensile specimens before tensile tests via a cathodic charging process. The loss of notch tensile strength (NTS) due to the charged hydrogen was used to evaluate the hydrogen embrittlement sensitivity. The results show that δ phase has deleterious effect on NTSs, and the fracture of hydrogen-charged specimens initiated near the notch surfaces. The loss of NTS caused by precharged hydrogen can be greatly decreased by dissolving δ phase. δ-free Inconel 718 alloy is proposed for the applications in hydrogen environments.展开更多
The effect of shot peening（SP） on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure ob...The effect of shot peening（SP） on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure observation, microhardness, and X-ray diffraction residual stress studies were also conducted on the steel. The results show that the shot peening specimens exhibit a higher resistance to hydrogen embrittlement in comparison with the no shot peening（NSP） specimens under the same hydrogen-charging current density. In addition, SP treatment sharply decreases the apparent hydrogen diffusivity and increases the subsurface hydrogen concentration. These findings are attributed to the changes in microstructure and compressive residual stress in the surface layer by SP. Scanning electron microscope fractographs reveal that the fracture surface of the NSP specimen exhibits the intergranular and quasi-cleavage mixed fracture modes, whereas the SP specimen shows only the quasi-cleavage fractures under the same hydrogen charging conditions, implying that the SP treatment delays the onset of intergranular fracture.展开更多
A plasma spraying plus laser remelting technique has been performed. onaustenite stainless steel (22Cr-13Ni-5Mn ) with a newly developed hydrogen resistantcoating material. The results show that the surface cladding l...A plasma spraying plus laser remelting technique has been performed. onaustenite stainless steel (22Cr-13Ni-5Mn ) with a newly developed hydrogen resistantcoating material. The results show that the surface cladding layer can effectively reducethe hydrogen content increasing of the stainless steel under the atmosphere of high pres-sure (30MPa), high temperature (300℃) and high purity (99. 995%) hydrogen andgreatly improve the hydrogen embrittlement resistance of the stain1ess steel. Throughanalysis of microstructure, a mechanism of hydrogen embrittlement resistance is presentedthat at room temperature, the surface oxidation films, both existing on the surface ofcoated and uncoated specimens, inhibit the adsorption and diffusion of hydrogen molecu-lae. However, at high temperature, it is the surface cladding layer with relatively low sol-ubility and Permeability for hydrogen that significantly reduces the amount of hydrogenentering into the interior of the material and improves its hydrogen embrittfement resis-tance.展开更多
After analyzing the phenomena and processes of hydrogen embrittlement of NdFeB permanent magnets, RF magnetron sputtering was used to fabricate Al thin films and then oxidized to form the Al/Al_2O_3 composite films on...After analyzing the phenomena and processes of hydrogen embrittlement of NdFeB permanent magnets, RF magnetron sputtering was used to fabricate Al thin films and then oxidized to form the Al/Al_2O_3 composite films on the magnets as the hydrogen resistance coatings. SEM and EDS were used to examine the morphology and composition respectively. Hydrogen resistance performance was tested by exposing the magnets in 10 MPa hydrogen gas at room temperature. The results show that the magnets with 8 μm Al/Al_2O_3 coatings can withstand hydrogen of 10 MPa for 65 min without being embrittled into powder. The samples with and without hydrogen resistance coatings have almost the same magnetic properties.展开更多
Effects of 650℃ aging for 1—1000 h on structure and hydrogen embrittlement susceptibility (HES)of steel Cr21Ni6Mn9N have been investigated.The results show that M_(23)C_6 type carbide precipitates at grain boundarie...Effects of 650℃ aging for 1—1000 h on structure and hydrogen embrittlement susceptibility (HES)of steel Cr21Ni6Mn9N have been investigated.The results show that M_(23)C_6 type carbide precipitates at grain boundaries and Cr-depletive region appears beside them during aging.The precipitates grow and connect each other as the aging time prolongs.Meanwhile, the degree of Cr-depletion aggravates first and then recovers gradually while the aging time is very long,i.e.,1000 h.The HES of the steel increases with increasing aging time but does not reduce with the recovery of Cr content at the Cr-depletive region.That implies that the ex- isting of carbides at grain boundaries might be the main reason which promotes the HES of steel during aging.展开更多
The ductility loss and threshold stress intensity,K_(IH)during hydrogen charging were measured for pure Ni and four Ni-Fe fcc alloys.The results show that ductility loss in 40Ni60Fe alloy and K_(IH)a 50Ni50Fe alloy ha...The ductility loss and threshold stress intensity,K_(IH)during hydrogen charging were measured for pure Ni and four Ni-Fe fcc alloys.The results show that ductility loss in 40Ni60Fe alloy and K_(IH)a 50Ni50Fe alloy have a minimum value.The variations of the amounts of hydride, hydrogen evolution and dislocation structure with composition have been investigated.The va- riation of hydrogen embrittlement susceptibility with composition measured by ductility loss and by K_(IH)or K_(IH)/K_C can be explained by means of the synthetical effects of amount of hydride,solutionized hydrogen and the extent of dislocation planarity on hydrogen embrittlement susceptibility.展开更多
In this study, the effect of vanadium addition(0.25%) on microstructure and hydrogen embrittlement(HE) was investigated in grade 12.9 bolt steels, and hydrogen diffusion was analyzed by hydrogen permeation.The results...In this study, the effect of vanadium addition(0.25%) on microstructure and hydrogen embrittlement(HE) was investigated in grade 12.9 bolt steels, and hydrogen diffusion was analyzed by hydrogen permeation.The results show that the addition of 0.25% vanadium in bolt steels can significantly improve the HE resistance.Vanadium addition can form a large number of vanadium precipitates, resulting in the uniform distribution of hydrogen and reduction of hydrogen accumulated at local grain boundaries, which promotes the inhibition of hydrogen-induced cracking.展开更多
Hydrogen embrittlement (HE) is a dangerous reaction that puzzled the material world for a long time. Hydrogen embrittlement is a type of deterioration which can be linked to corrosion and corrosion-control processes. ...Hydrogen embrittlement (HE) is a dangerous reaction that puzzled the material world for a long time. Hydrogen embrittlement is a type of deterioration which can be linked to corrosion and corrosion-control processes. It involves the introduction of hydrogen into a component, an event that can seriously reduce the ductility and load-bearing capacity, cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Presently this phenomenon is not completely understood and hydrogen embrittlement detection, in particular, seems to be one of the most difficult aspects of the problem. Although the process cannot be understand completely, method such as baking can reverse the process of hydrogen embrittlement and RSL (Rising Step Load) testing presents an excellent way to test the susceptibility to hydrogen embrittlement in the steel and its alloys. Different specimens were made to facilitate the testing. This study determines the effect of coating process have on the brittleness of the material and use of RSL (Risisng Step Load) mechanical loading test method to qualify plating processes for the risk of internal hydrogen embrittlement. The paper introduces the different causes of the hydrogen embrittlement, especially the zinc coating process and the hot dip galvanizing process. Subsequently, hydrogen embrittlement prevention and testing are discussed, as well as the current McGill-established RSL (Rising Step Load) bend testing’s principle, potential set-up, tested specimens and some of the critical results. Finally, some of the future development of the hydrogen embrittlement prevention will be covered.展开更多
The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimen...The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimens are observed by scanning electron microscopy.The HE susceptibility of the X52 pipeline steel material increases with an increase in both hydrogen charging time and hydrogen pressure.At a charging time of 96 h,the HE susceptibility index reaches 45.86%,approximately 3.6 times that at a charging time of 0 h.Similarly,a charging pressure of 4 MPa results in a HE susceptibility index of 31.61%,approximately 2.5 times higher than that at a charging pressure of 0.3 MPa.展开更多
Hydrogen embrittlement remains a crucial concern in industries that rely on high-strength materials.Exposure to hydrogen poses a significant threat to the mechanical integrity of such materials.This review article bri...Hydrogen embrittlement remains a crucial concern in industries that rely on high-strength materials.Exposure to hydrogen poses a significant threat to the mechanical integrity of such materials.This review article briefly discusses the fundamentals of hydrogen embrittlement,including its mechanisms and the effects of various factors,such as chemical composition and environmental conditions.Several heat treatments have been developed to eliminate the risk of hydrogen embrittlement.Among various suggested heat treatments,the retrogression-reaging(RRA)treatment has proven effective in optimizing the balance between mechanical properties and resistance to hydrogen embrittlement.This review highlights the role of RRA treatment in modifying the microstructure of Al-Zn-Mg alloys to enhance their ability to resist hydrogen embrittlement,building on existing literature.An interesting aspect explored in this article is the intricate relationship between pre-deformation and subsequent RRA treatment.Additionally,the review discusses the use of RRA as a post-weld heat treatment to mitigate the susceptibility of weldments to hydrogen embrittlement.A comprehensive exploration of these topics is beneficial for a thorough understanding of the multifaceted functions of RRA treatment.However,despite its advantages,the widespread adoption of RRA treatment in the industry is hindered by certain challenges.This review addresses these challenges,offering insights into the latest strategies to overcome them.展开更多
Given the carbon peak and carbon neutrality era,there is an urgent need to develop high-strength steel with remarkable hydrogen embrittlement resistance.This is crucial in enhancing toughness and ensuring the utilizat...Given the carbon peak and carbon neutrality era,there is an urgent need to develop high-strength steel with remarkable hydrogen embrittlement resistance.This is crucial in enhancing toughness and ensuring the utilization of hydrogen in emerging iron and steel materials.Simultaneously,the pursuit of enhanced metallic materials presents a cross-disciplinary scientific and engineering challenge.Developing high-strength,toughened steel with both enhanced strength and hydrogen embrittlement(HE)resistance holds significant theoretical and practical implications.This ensures secure hydrogen utilization and further carbon neutrality objectives within the iron and steel sector.Based on the design principles of high-strength steel HE resistance,this review provides a comprehensive overview of research on designing surface HE resistance and employing nanosized precipitates as intragranular hydrogen traps.It also proposes feasible recommendations and prospects for designing high-strength steel with enhanced HE resistance.展开更多
Hydrogen embrittlement behavior, micro-deformation, and crack propagation mechanism of CoCrFeNiMn high-entropy alloy (HEA) fabricated by laser powder bed fusion (LPBF) under different parameters were investigated by s...Hydrogen embrittlement behavior, micro-deformation, and crack propagation mechanism of CoCrFeNiMn high-entropy alloy (HEA) fabricated by laser powder bed fusion (LPBF) under different parameters were investigated by slow strain rate tensile tests (at room temperature) with/without electrochemical hydrogen pre-charging. The LPBF CoCrFeNiMn HEA shows excellent resistance to hydrogen embrittlement. Unsuitable LPBF parameters are accompanied by many microcracks and holes, resulting in a slight decrease in the hydrogen embrittlement resistance of the material. The electron backscatter diffraction (EBSD), electron channeling contrast image (ECCI) techniques, and transmission electron microscope (TEM) were carried out to research the main influencing factors of hydrogen on the deformation mechanism and crack propagation. Compared with un-charged samples, a larger number of deformation twins (DTs) appear in the deformation process of hydrogen-charged LPBF CoCrFeNiMn, attributing to the reduction of stacking fault energy (SFE) due to the ingress of hydrogen. The nano DTs and crossing twin system contribute to the extra work hardening, and a strain hardening platform is observed for all hydrogen-charged samples, resulting in the increase of strain hardening rate or the mitigation of the loss of strain hardening. Although unsuitable process parameters will trigger fabrication defects and reduce mechanical properties, the cellular structure can bring a hydrogen-induced strain hardening platform for LPBF CoCrFeNiMn to reduce the damage caused by hydrogen embrittlement.展开更多
The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parame...The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parameters,and test methods of HE,as well as the characteristics and path of HE fractures,are introduced.The mechanisms and modes of crack propagation of HE and hydrogen-induced delayed fracture are reviewed.The recent progress surrounding micro and macro typical fracture characteristics and the influencing factors of HE are discussed.Finally,methods for improving HE resistance can be summarized as follows:(1)reducing crystalline grain and inclusion sizes(oxides,sulfides,and titanium nitride),(2)controlling nano-precipitates(niobium carbide,titanium carbide,and composite precipitation),and(3)increasing residual austenite content under the reasonable tension strength of steel.展开更多
A microstructure composed of martensite matrix,lower bainite,and stable film-like austenite was designed by a quenching and isothermal bainitic holding process in a 0.30C–2.69Mn–1.71Si(wt.%)steel.The yield strength,...A microstructure composed of martensite matrix,lower bainite,and stable film-like austenite was designed by a quenching and isothermal bainitic holding process in a 0.30C–2.69Mn–1.71Si(wt.%)steel.The yield strength,tensile strength,and ductile-to-brittle transition temperature(DBTT)of the high-strength steel thus obtained were 1263 MPa,1521 MPa,and-33℃,respectively,and at-20℃,it showed superior low-temperature toughness,which reached 77.5 J/cm^(2).Meanwhile,it showed excellent hydrogen embrittlement(HE)resistance,and the total elongation loss is only 3.1%after 15 min of hydrogen charging.The excellent comprehensive performance is attributed to the fact that fine stable austenite with film-like morphology hindered the crack nucleation and propagation,and hindered hydrogen diffusion as a hydrogen trap.However,with a decrease in the isothermal temperature,transition carbide precipitation was accompanied by a further decrease in austenite grain size.For this condition,although transition carbides can act as effective hydrogen traps,excessive precipitation decreased the carbon content of retained austenite and increased the deformation heterogeneity between austenite and martensite matrix,leading to weakened austenite stability and HE resistance,a total elongation loss of approximately 39%(15 min hydrogen charging),a sharp decrease in impact toughness,and an increase in DBTT.The competitive role of film-like austenite and transition carbides on the comprehensive mechanical performance of steel is revealed,especially the suppression of crack nucleation and propagation that will provide a guide for the design of high strength steels with excellent impact toughness and HE resistance.展开更多
Press-hardened steel(PHS)with an ultimate tensile strength(UTS)of 1500 MPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achi...Press-hardened steel(PHS)with an ultimate tensile strength(UTS)of 1500 MPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achieved by hot stamping process.However,the application of PHS with UTS exceeding 1500 MPa in automotive industry could be deferred due to the increased risk of hydrogen embrittlement.To reduce this kind of risk,recent research efforts have been focused on various ways to optimize the microstructure of PHS.The present review intends to summarize these efforts,to highlight present solutions to address hydrogen embrittlement,and to shed light on directions for future improvement.The influence of microstructure on the hydrogen embrittlement of PHS has been discussed in terms of both the steel substrate and the surface condition.The substrate part covers the influence of martensite,carbides,inclusions,and retained austenite,while the surface part covers decarburization and oxidation,pre-coating,and trimming.展开更多
文摘Nitriding of the surface in martensitic stainless steels is commonly carried out to improve their wear resistance. The process of plasma nitriding in stainless steel is influenced by two mechanisms: physical diffusion through the surface and chemical gas-metal reaction. The inner nitriding interaction involves the simultaneous penetration and formation of a solid solution, as well as the interaction of nitrogen with specific alloying elements, resulting in the development of homogeneous and heterogeneous structures. Our study concludes that the observed intergranular hydrogen embrittlement and crack formation during the surface nitridation process of AMS 5719 martensite alloy steel can be attributed to the ammonium concentration of approximately 50% at a temperature of 530˚C.
基金financially supported by the National Natural Science Foundation of China (Nos. 51805292, 51671215, and 51425502)the National Postdoctoral Program for Innovative Talents of China (No. BX201700132)
文摘This study investigated the susceptibility of X80 pipeline steel to hydrogen embrittlement given different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles in H2S environment.The fracture strain of the steel samples decreased with increasing hydrogen pre-charging time;this steel degradation could almost be recovered after diffusible hydrogen was removed when the hydrogen pre-charging time was<8 d.However,unrecoverable degeneration occurred when the hydrogen pre-charging time extended to 16–30 d.Moreover,nanovoid formation meant that the hydrogen damage to the steel under intermittent hydrogen pre-charging–releasing–recharging conditions was more serious than that under continuous hydrogen pre-charging conditions.This study illustrated that the mechanical degradation of steel is inevitable in an H2S environment even if diffusible hydrogen is removed or visible hydrogen-induced cracking is neglected.Furthermore,the steel samples showed premature fractures and exhibited a hydrogen fatigue effect because the repeated entry and release of diffusible hydrogen promoted the formation of vacancies that aggregated into nanovoids.Our results provide valuable information on the mechanical degradation of steel in an H2S environment,regarding the change rules of steel mechanical properties under different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles.
基金the financial support received from the National Natural Science Foundation of China(Nos.U1706221,51922002,and 51771025)the Fundamental Research Funds for the Central Universities(No.FRF-TP17-19-003C1Z)the special sponsor for the Research Student Attachment Program from the graduate school of the University of Science and Technology Beijing。
文摘We investigated the critical influence of in-situ nanoparticles on the mechanical properties and hydrogen embrittlement(HE)of high-strength steel.The results reveal that the mechanical strength and elongation of quenched and tempered steel(919 MPa yield strength,17.11%elongation)are greater than those of hot-rolled steel(690 MPa yield strength,16.81%elongation)due to the strengthening effect of insitu Ti_(3)O_(5)–Nb(C,N)nanoparticles.In addition,the HE susceptibility is substantially mitigated to 55.52%,approximately 30%lower than that of steels without in-situ nanoparticles(84.04%),which we attribute to the heterogeneous nucleation of the Ti_(3)O_5 nanoparticles increasing the density of the carbides.Compared with hard TiN inclusions,the spherical and soft Al_(2)O_(3)–MnS core–shell inclusions that nucleate on in-situ Al_(2)O_(3) particles could also suppress HE.In-situ nanoparticles generated by the regional trace-element supply have strong potential for the development of high-strength and hydrogen-resistant steels.
文摘An electronic approach to the mechanism of hydrogen embrittlement in metals is pre-sented and discussed. Some problems of the mechanism of hydrogen embrittlement are pointed out from an electronic point of view. Electronic structure calculations in a periodically cleaved or slipped lattice are developed in orker to identofy deformation-sensitive electronic states in the absence of hydrogen. The calculational results are given and discussed for a trunsition metal, Pd. Electronic structure calculations in the presence of hydrogen are outlined and hydrogen embrittlement in transition metals is discussed in terms of electronic states.
基金Projects(51908496,51878610,51820105012,51778577,51638013)supported by the National Natural Science Foundation of ChinaProjects(LY18E080003,LQ19E080011,LQ19E080012,LQ20E080001)supported by the Natural Science Foundation of Zhejiang Province,ChinaProject(2018A610359)supported by the Natural Science Foundation of Ningbo,China。
文摘Bidirectional electromigration rehabilitation(BIEM)is a novel electrochemical rehabilitation method involving the injection of inhibitors into steel bar surface.The BIEM effect and hydrogen embrittlement(HE)risk depend on the electrochemical parameters(current density and duration)and operating condition(stress level and concrete cover thickness)of reinforced concrete structures.Experiments were performed in this study to investigate the relationships between the aforementioned factors.For a small current density group,a linear relationship was established between electric flux and chloride extraction.For a large current density group,the reasonable current density,stress level,and treatment time were obtained.Finally,the querying method of electrochemical parameters combined with treatment time and current density was proposed.
文摘The effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 was investigated by conducting notch tensile tests. Notch tensile specimens with various precipitation morphologies of δ phase were prepared with different heat treatments, and hydrogen was charged into the tensile specimens before tensile tests via a cathodic charging process. The loss of notch tensile strength (NTS) due to the charged hydrogen was used to evaluate the hydrogen embrittlement sensitivity. The results show that δ phase has deleterious effect on NTSs, and the fracture of hydrogen-charged specimens initiated near the notch surfaces. The loss of NTS caused by precharged hydrogen can be greatly decreased by dissolving δ phase. δ-free Inconel 718 alloy is proposed for the applications in hydrogen environments.
基金financially supported by the Doctoral Research Assistant Foundation of Xi'an Jiaotong University
文摘The effect of shot peening（SP） on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure observation, microhardness, and X-ray diffraction residual stress studies were also conducted on the steel. The results show that the shot peening specimens exhibit a higher resistance to hydrogen embrittlement in comparison with the no shot peening（NSP） specimens under the same hydrogen-charging current density. In addition, SP treatment sharply decreases the apparent hydrogen diffusivity and increases the subsurface hydrogen concentration. These findings are attributed to the changes in microstructure and compressive residual stress in the surface layer by SP. Scanning electron microscope fractographs reveal that the fracture surface of the NSP specimen exhibits the intergranular and quasi-cleavage mixed fracture modes, whereas the SP specimen shows only the quasi-cleavage fractures under the same hydrogen charging conditions, implying that the SP treatment delays the onset of intergranular fracture.
文摘A plasma spraying plus laser remelting technique has been performed. onaustenite stainless steel (22Cr-13Ni-5Mn ) with a newly developed hydrogen resistantcoating material. The results show that the surface cladding layer can effectively reducethe hydrogen content increasing of the stainless steel under the atmosphere of high pres-sure (30MPa), high temperature (300℃) and high purity (99. 995%) hydrogen andgreatly improve the hydrogen embrittlement resistance of the stain1ess steel. Throughanalysis of microstructure, a mechanism of hydrogen embrittlement resistance is presentedthat at room temperature, the surface oxidation films, both existing on the surface ofcoated and uncoated specimens, inhibit the adsorption and diffusion of hydrogen molecu-lae. However, at high temperature, it is the surface cladding layer with relatively low sol-ubility and Permeability for hydrogen that significantly reduces the amount of hydrogenentering into the interior of the material and improves its hydrogen embrittfement resis-tance.
文摘After analyzing the phenomena and processes of hydrogen embrittlement of NdFeB permanent magnets, RF magnetron sputtering was used to fabricate Al thin films and then oxidized to form the Al/Al_2O_3 composite films on the magnets as the hydrogen resistance coatings. SEM and EDS were used to examine the morphology and composition respectively. Hydrogen resistance performance was tested by exposing the magnets in 10 MPa hydrogen gas at room temperature. The results show that the magnets with 8 μm Al/Al_2O_3 coatings can withstand hydrogen of 10 MPa for 65 min without being embrittled into powder. The samples with and without hydrogen resistance coatings have almost the same magnetic properties.
文摘Effects of 650℃ aging for 1—1000 h on structure and hydrogen embrittlement susceptibility (HES)of steel Cr21Ni6Mn9N have been investigated.The results show that M_(23)C_6 type carbide precipitates at grain boundaries and Cr-depletive region appears beside them during aging.The precipitates grow and connect each other as the aging time prolongs.Meanwhile, the degree of Cr-depletion aggravates first and then recovers gradually while the aging time is very long,i.e.,1000 h.The HES of the steel increases with increasing aging time but does not reduce with the recovery of Cr content at the Cr-depletive region.That implies that the ex- isting of carbides at grain boundaries might be the main reason which promotes the HES of steel during aging.
文摘The ductility loss and threshold stress intensity,K_(IH)during hydrogen charging were measured for pure Ni and four Ni-Fe fcc alloys.The results show that ductility loss in 40Ni60Fe alloy and K_(IH)a 50Ni50Fe alloy have a minimum value.The variations of the amounts of hydride, hydrogen evolution and dislocation structure with composition have been investigated.The va- riation of hydrogen embrittlement susceptibility with composition measured by ductility loss and by K_(IH)or K_(IH)/K_C can be explained by means of the synthetical effects of amount of hydride,solutionized hydrogen and the extent of dislocation planarity on hydrogen embrittlement susceptibility.
文摘In this study, the effect of vanadium addition(0.25%) on microstructure and hydrogen embrittlement(HE) was investigated in grade 12.9 bolt steels, and hydrogen diffusion was analyzed by hydrogen permeation.The results show that the addition of 0.25% vanadium in bolt steels can significantly improve the HE resistance.Vanadium addition can form a large number of vanadium precipitates, resulting in the uniform distribution of hydrogen and reduction of hydrogen accumulated at local grain boundaries, which promotes the inhibition of hydrogen-induced cracking.
文摘Hydrogen embrittlement (HE) is a dangerous reaction that puzzled the material world for a long time. Hydrogen embrittlement is a type of deterioration which can be linked to corrosion and corrosion-control processes. It involves the introduction of hydrogen into a component, an event that can seriously reduce the ductility and load-bearing capacity, cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Presently this phenomenon is not completely understood and hydrogen embrittlement detection, in particular, seems to be one of the most difficult aspects of the problem. Although the process cannot be understand completely, method such as baking can reverse the process of hydrogen embrittlement and RSL (Rising Step Load) testing presents an excellent way to test the susceptibility to hydrogen embrittlement in the steel and its alloys. Different specimens were made to facilitate the testing. This study determines the effect of coating process have on the brittleness of the material and use of RSL (Risisng Step Load) mechanical loading test method to qualify plating processes for the risk of internal hydrogen embrittlement. The paper introduces the different causes of the hydrogen embrittlement, especially the zinc coating process and the hot dip galvanizing process. Subsequently, hydrogen embrittlement prevention and testing are discussed, as well as the current McGill-established RSL (Rising Step Load) bend testing’s principle, potential set-up, tested specimens and some of the critical results. Finally, some of the future development of the hydrogen embrittlement prevention will be covered.
基金This work was supported by the National Key R&D Program of China(2021YFB4001601)the Youth Innovation Promotion Association CAS(2022187).
文摘The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile tests.The fracture morphologies of the specimens are observed by scanning electron microscopy.The HE susceptibility of the X52 pipeline steel material increases with an increase in both hydrogen charging time and hydrogen pressure.At a charging time of 96 h,the HE susceptibility index reaches 45.86%,approximately 3.6 times that at a charging time of 0 h.Similarly,a charging pressure of 4 MPa results in a HE susceptibility index of 31.61%,approximately 2.5 times higher than that at a charging pressure of 0.3 MPa.
基金funded by the Centre Quebecois de Recherche et de Developpement de l’Aluminium(CQRDA)the Natural Sciences and Engineering Research Council of Canada(NSERC)under Grant Number ALLRP 586335-23.
文摘Hydrogen embrittlement remains a crucial concern in industries that rely on high-strength materials.Exposure to hydrogen poses a significant threat to the mechanical integrity of such materials.This review article briefly discusses the fundamentals of hydrogen embrittlement,including its mechanisms and the effects of various factors,such as chemical composition and environmental conditions.Several heat treatments have been developed to eliminate the risk of hydrogen embrittlement.Among various suggested heat treatments,the retrogression-reaging(RRA)treatment has proven effective in optimizing the balance between mechanical properties and resistance to hydrogen embrittlement.This review highlights the role of RRA treatment in modifying the microstructure of Al-Zn-Mg alloys to enhance their ability to resist hydrogen embrittlement,building on existing literature.An interesting aspect explored in this article is the intricate relationship between pre-deformation and subsequent RRA treatment.Additionally,the review discusses the use of RRA as a post-weld heat treatment to mitigate the susceptibility of weldments to hydrogen embrittlement.A comprehensive exploration of these topics is beneficial for a thorough understanding of the multifaceted functions of RRA treatment.However,despite its advantages,the widespread adoption of RRA treatment in the industry is hindered by certain challenges.This review addresses these challenges,offering insights into the latest strategies to overcome them.
基金the National Key Research and Development Program of China(No.2022YFB3709000)the National Natural Science Foundation of China(Nos.52201060 and 51922002)+2 种基金the China Postdoctoral Science Foundation(Nos.BX20220035 and 2022M710347)Science Center for Gas Turbine Project(No.P2022-B-IV-008-001)the Open Fund of State Key Laboratory of New Metal Materials,University of Science and Technology Beijing(No.2022Z-18)。
文摘Given the carbon peak and carbon neutrality era,there is an urgent need to develop high-strength steel with remarkable hydrogen embrittlement resistance.This is crucial in enhancing toughness and ensuring the utilization of hydrogen in emerging iron and steel materials.Simultaneously,the pursuit of enhanced metallic materials presents a cross-disciplinary scientific and engineering challenge.Developing high-strength,toughened steel with both enhanced strength and hydrogen embrittlement(HE)resistance holds significant theoretical and practical implications.This ensures secure hydrogen utilization and further carbon neutrality objectives within the iron and steel sector.Based on the design principles of high-strength steel HE resistance,this review provides a comprehensive overview of research on designing surface HE resistance and employing nanosized precipitates as intragranular hydrogen traps.It also proposes feasible recommendations and prospects for designing high-strength steel with enhanced HE resistance.
基金financially supported by the State Key Lab of Advanced Metals and Materials of China(Grant No.2020-Z18)National Natural Science Foundation of China(Grant No.52071014)Fundamental Research Funds for the Central Universities(No.FRF-MP-20-51,FRF-BD-20-28A2).
文摘Hydrogen embrittlement behavior, micro-deformation, and crack propagation mechanism of CoCrFeNiMn high-entropy alloy (HEA) fabricated by laser powder bed fusion (LPBF) under different parameters were investigated by slow strain rate tensile tests (at room temperature) with/without electrochemical hydrogen pre-charging. The LPBF CoCrFeNiMn HEA shows excellent resistance to hydrogen embrittlement. Unsuitable LPBF parameters are accompanied by many microcracks and holes, resulting in a slight decrease in the hydrogen embrittlement resistance of the material. The electron backscatter diffraction (EBSD), electron channeling contrast image (ECCI) techniques, and transmission electron microscope (TEM) were carried out to research the main influencing factors of hydrogen on the deformation mechanism and crack propagation. Compared with un-charged samples, a larger number of deformation twins (DTs) appear in the deformation process of hydrogen-charged LPBF CoCrFeNiMn, attributing to the reduction of stacking fault energy (SFE) due to the ingress of hydrogen. The nano DTs and crossing twin system contribute to the extra work hardening, and a strain hardening platform is observed for all hydrogen-charged samples, resulting in the increase of strain hardening rate or the mitigation of the loss of strain hardening. Although unsuitable process parameters will trigger fabrication defects and reduce mechanical properties, the cellular structure can bring a hydrogen-induced strain hardening platform for LPBF CoCrFeNiMn to reduce the damage caused by hydrogen embrittlement.
基金This work was financially supported by the State Key Laboratory of Vehicle NVH and Safety Technology(NVHSKL-202104)the innovation research group of universities in Chongqing(CXQT21030,CXQT19031).
文摘The hydrogen embrittlement(HE)fracture of advanced high-strength steels used in lightweight automobiles has received increasing public attention.The source,transmission,and movement of hydrogen,characterization parameters,and test methods of HE,as well as the characteristics and path of HE fractures,are introduced.The mechanisms and modes of crack propagation of HE and hydrogen-induced delayed fracture are reviewed.The recent progress surrounding micro and macro typical fracture characteristics and the influencing factors of HE are discussed.Finally,methods for improving HE resistance can be summarized as follows:(1)reducing crystalline grain and inclusion sizes(oxides,sulfides,and titanium nitride),(2)controlling nano-precipitates(niobium carbide,titanium carbide,and composite precipitation),and(3)increasing residual austenite content under the reasonable tension strength of steel.
基金the National Key R&D Program of China(No.2021YFB3702401)Major Program of the National Natural Science Foundation of China(No.52293394)the National Natural Science Foundation of China(Nos.U1564203,51571141 and 51201105).
文摘A microstructure composed of martensite matrix,lower bainite,and stable film-like austenite was designed by a quenching and isothermal bainitic holding process in a 0.30C–2.69Mn–1.71Si(wt.%)steel.The yield strength,tensile strength,and ductile-to-brittle transition temperature(DBTT)of the high-strength steel thus obtained were 1263 MPa,1521 MPa,and-33℃,respectively,and at-20℃,it showed superior low-temperature toughness,which reached 77.5 J/cm^(2).Meanwhile,it showed excellent hydrogen embrittlement(HE)resistance,and the total elongation loss is only 3.1%after 15 min of hydrogen charging.The excellent comprehensive performance is attributed to the fact that fine stable austenite with film-like morphology hindered the crack nucleation and propagation,and hindered hydrogen diffusion as a hydrogen trap.However,with a decrease in the isothermal temperature,transition carbide precipitation was accompanied by a further decrease in austenite grain size.For this condition,although transition carbides can act as effective hydrogen traps,excessive precipitation decreased the carbon content of retained austenite and increased the deformation heterogeneity between austenite and martensite matrix,leading to weakened austenite stability and HE resistance,a total elongation loss of approximately 39%(15 min hydrogen charging),a sharp decrease in impact toughness,and an increase in DBTT.The competitive role of film-like austenite and transition carbides on the comprehensive mechanical performance of steel is revealed,especially the suppression of crack nucleation and propagation that will provide a guide for the design of high strength steels with excellent impact toughness and HE resistance.
基金M.X.Huang acknowledges the support from Guangzhou Municipal Science and Technology Project(No.202007020007)Guangdong Basic and Applied Basic Research Foundation of China(No.2020B1515130007).
文摘Press-hardened steel(PHS)with an ultimate tensile strength(UTS)of 1500 MPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achieved by hot stamping process.However,the application of PHS with UTS exceeding 1500 MPa in automotive industry could be deferred due to the increased risk of hydrogen embrittlement.To reduce this kind of risk,recent research efforts have been focused on various ways to optimize the microstructure of PHS.The present review intends to summarize these efforts,to highlight present solutions to address hydrogen embrittlement,and to shed light on directions for future improvement.The influence of microstructure on the hydrogen embrittlement of PHS has been discussed in terms of both the steel substrate and the surface condition.The substrate part covers the influence of martensite,carbides,inclusions,and retained austenite,while the surface part covers decarburization and oxidation,pre-coating,and trimming.
