Hydrogen Trapping by Dislocations and Grain Boundaries in Fe-3%Si AHoy

In present work,Fe-3%Si alloy specimens with various degrees of cold working and various grain sizes were chosen to determine the effect of cold working and grain sizes on the hydrogen diffusivities by electrochemical permeation method and the mechanism of hydrogen trapping by dis- ocations and grain boundaries is discussed.

Hydrogen Trapping Phenomenon at Grain Boundaries in a 18Ni Maraging Steel

An investigation of the phenomenon of hydrogen trapping at grain boundaries in 18 Ni maraging steel has been carried out by the thermal hydrogen evolution technique.Grain boundary on- ly acts as a trapping site of hydrogen at low temper- ature region,and the peak of its hydrogen evolution from it is observed at 405K with 3.00K/rain heat- ing rate and with specimen of 0.55mm thick.The trap activation energy of hydrogen escaped from grain boundary is estimated as 14.2kJ/mol. Hydrogen trapping at grain boundary is mainly as sociated with segregated hydrogen by impurities, and its behaviour is primarily the interaction be- tween hydrogen and the hydrostatic stress field of the grain boundary.

Addition of cerium and yttrium to ferritic steel weld metal to improve hydrogen trapping efficiency

The applicability of Ce and Y as promising candidate elements to form irreversible traps in weld metal was investigated by thermal desorption spectroscopy(TDS) with gas chromatography(GC). The precise nature of the precipitate particles newly formed in the weld metal by the addition of Ce and Y to a certain alloy system was characterized. Moreover,the hydrogen trapping efficiency expressed as the reduction of the diffusible hydrogen in the weld metal was analyzed. The results showed that the addition of Ce and/or Y to this alloy system led to the formation of a mixed type of(Ce,Ti)-based oxide,(Y,Ni)-based carbide,or(Ce,Y,Ti)-based oxide particles. Because of the high activation energy of the mixed type of particles(≥ 150 k J/mol),the trapping efficiency for hydrogen was considered to be sufficiently high to effectively reduce the diffusible hydrogen content.

Hydrogen trapping in high strength 0Cr16Ni5Mo martensitic stainless steel

Hydrogen trapping behavior has been investigated by means of thermal desorption spectroscopy(TDS) for a high strength steel after it was tempered at the temperatures of 430 °C, 500 °C and 520 °C, respectively. The loss of ductility was characterized by slow strain rate test(SSRT) and microscopic observation. It shows that with hydrogen charging the fracture feature transfers from ductile to brittle, resulting in the loss of ductility. Undeformed microstructure immediately beneath the fracture surface in charged specimen corresponds to badly ductility compared to the obviously streamline plastic deformation in uncharged specimen. The activation energies for the peaks present in the TDS analysis are calculated for all tested steel and the activation energies for all temperature peaks are similar, corresponding to the similar types of hydrogen traps.

Interactions between Pre-strain and Dislocation Structures and Its Effect on the Hydrogen Trapping Behaviors

This work investigated the effect of pre-strain and microstructures and their interactions on hydrogen trapping behaviors in case of 1-GPa high-strength martensitic steel Fe-0.05C-0.30Si-1.10Mn-3.50Ni-0.53Cr-0.50Mo-0.03 V(wt%).We found that the trapped reversible and trapped irreversible hydrogen contents increased significantly after applying a pre-strain of 5%,with an increase in the trapped reversible hydrogen content from 0.6 ppm in the original sample to 2.1 ppm.The hydrogen desorption activation energy also showed a slight increase.The microstructural evolution revealed that the concomitant dislocation cell-twin duplex microstructure with high-density tangled dislocations after pre-strain substantially increased the trapped reversible hydrogen contents.Additionally,the tangled dislocations pinned by the nanoprecipitates acted as deep irreversible hydrogen traps,increasing the trapped hydrogen at high temperatures after applying 5%pre-strain.These findings provide an expanded understanding of the hydrogen trapping behaviors of pre-strained microstructures.

Ab Initio Investigations for the Role of Compositional Complexities in Affecting Hydrogen Trapping and Hydrogen Embrittlement:A Review

ydrogen embrittlement(HE)seriously restricts the service safety of structural metallic materials applicate in aerospace,ocean,and transportation.Recent studies aiming at increasing the HE-resistance have been focusing on trapping diffusible H atoms by inherent microstructural features in materials.Alloying-induced compositional complexities,including different types of solute atoms,lattice chemical heterogeneities,and carbide precipitates,have attracted research efforts regarding the H trapping capabilities and potential to reduce the susceptibility to HE.In this paper,we review recent progress in exploiting compositional complexities to regulate the hydrogen trapping characteristics and mechanical properties in H-containing environments.The focus is placed on results and insights from ab initio calculations based on density functional theory(DFT).Quantitative predictions of trapping parameters and atomic scale details that are hardly to be gained through traditional experimental characterizations are provided.Additionally,we overview the electronic/atomistic mechanisms of H trapping energetics in metallic materials.Finally,we propose some key challenges and prospects in simulation of defect interactions,interpretation of experimental characterizations,and developing microstructure-based H diffusion prediction models.For the applications of first principle calculations,we illustrate how the DFT data can complement experimental characterizations to guide composition and microstructure design for better HE-resistant materials.

Review on the design of high-strength and hydrogen-embrittlement-resistant steels

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.

Analysis of Hydrogen Diffusion in Metals with Trapping under Local Equilibrium Assumption

The assumption of the local equilibrium of hydrogen distribution in metals[1]was used in the model formerly developed[2]to describe the diffu- sion of hydrogen in metals.From the assumption a direct relationship between the hydrogen diffusivity and the hydrogen concentration in metals is estab- lished as D=D_o/{1+N_x(k/p)/[1+C(k/p)]} The comparison between the two results drawn from the assumption of equilibrium and the dynam- ics of hydrogen trapping[3]was also presented.The computation results well explained the scattering phenomenon existed in hydrogen diffusion data and suggested that the experimental conditions should be identical for the study of hydrogen permeation in metals.

STUDY ON BEHAVIOR OF TRAPPED HYDROGEN IN 18Ni MARAGING STEEL BY THERMAL HYDROGEN EVOLUTION TECHNIQUE

The interaction of hydrogen with interface between the precipitates and the martensitie matrix in 18Ni maraging steel has been studied by means of thermal evolution hydrogen technique us- ing gas chromatograph as hydrogen detector.An evolution rate peak has been observed at 451 K.The height of the peak relates to the amount and distribution of the precipitates.The activation energy for hydrogen escaping from the trap sites is 23.2 kJ/mol.

A New Analysis of Hydrogen Diffusion in Metals with Trapping

A new model of hydrogen diffusion in metals has been developed,it is more efficient to describe the hydrogen diffusion with trapping in metals.In the model newly developed an impli- cit dependence on time of hydrogen diffusion coefficient in metals with trapping was firstly built and it is shown that hydrogen diffusion coefficient will be different at different posi- tions in a dynamic process of hydrogen diffusion in a metal. Numerical solutions of the present model were obtained by finite difference method.By changing the parameters in the model the diffusion of hydrogen in a metal and the effect of trapping were described and discussed.And the comparison between the well known McNabb and Foster's model and the present model was also made.

焦化汽柴油加氢捕硅剂的制备及性能评价

目的脱除焦化汽柴油馏分中的有机硅化合物,避免催化剂硅中毒。方法以拟薄水铝石粉为载体制备原料,镍钼为活性金属组分,采用等体积浸渍法制备了加氢捕硅剂,利用N 2吸附脱附、X射线衍射、吡啶红外光谱、扫描电镜等方法对其进行分析表征,并在200 mL加氢中试装置上考查了捕硅剂的脱硅活性和2000 h活性稳定性。结果自主开发的捕硅剂比表面积和孔容较高,酸性适宜,活性金属分布均匀,强度满足工业装置装填要求。捕硅剂的脱硅活性较高,在典型的工业条件下,脱硅率>90%,在2000 h活性稳定性试验过程中,脱硅率稳定>90%,活性稳定性良好,且具有较高的容硅能力。结论自主开发的捕硅剂具有广阔的工业应用前景,对清洁燃料的生产及保护装置的长周期稳定运行具有十分重要的意义。

Application of the Hydrogen Diffusion Model to the Hydrogen Permeation

The model of hydrogen diffusion formerly de- veloped [1] has been applied successfully to the hydrogen permeation experiment results of three kinds of materials,α—Fe,Fe—Ti alloy and Fe—Ti—C alloy by the mathematical fitting method.From the fitting results it was shown that the model can re- fiect well the diffusion of hydrogen in the materials with trapping.The obtained trapping parameters(α and β)can be used to explain well the diffusion of hydrogen in the samples with trapping.

The role of hydrogen in negative bias temperature instability of pMOSFET

The NBTI degradation phenomenon and the role of hydrogen during NBT stress are presented in this paper. It is found that PBT stress can recover a fraction of Vth shift induced by NBT1. However, this recovery is unstable. The original degradation reappears soon after reapplication of the NBT stress condition. Hydrogen-related species play a key role during a device＇s NBT degradation. Experimental results show that the diffusion species are neutral, they repassivate Si dangling bond which is independent of the gate voltage polaxity. In addition to the diffusion towards gate oxide, hydrogen diffusion to Si-substrate must be taken into account for it also has important influence on device degradation during NBT stress.

Detection of Hydrogen Peroxide Photogenerating from a Hypocrellin B Derivative

In order to f urther improve the photosensitizing activity of hypocrellin B(HB), the complex o f 5,8 di Br HB with Al 3+ was designed and synthesized in high yield. Th e complex of aluminium ion with 5,8 di Br HB is a new water soluble perylene quinonoid derivative with enhanced absorption over HB in the phototherapeutic wi ndow (600-900 nm). Electron paramagnetic resonance (EPR) measurement and 9,10 diphenyl anthracene bleaching methods were used to investigate the photosensiti zing activity of [Al 2(5,8 di Br HB)Cl 4] n in the prese nce of oxygen. Singlet oxygen, superoxide anion radical, hydroxyl radical can be generated by [Al 2(5,8 di Br HB)Cl 4] n photosensit ization. The results showed that the production of hydroxyl radical ( · OH) by [Al 2(5,8 di Br HB)Cl 4] n photosensitization comes from the Fenton Haber Weiss reaction and the decom position of DMPO 1O 2 adduct. Formation of H 2O 2 as one of main intermedi ates in the photogeneration of hydroxyl radical was detected by using the cataly zed oxidation of the DPD reagent by the POD enzyme method. Moreover, the experim ents of EPR spin trap and catalase enzyme excluded the effect of organoperoxide on DPD oxidization. These results further support the proposed mechanism of · OH formation.

不可逆氢原子对高强度钢氢致延迟断裂行为的影响

采用升温脱氢分析测试技术并结合慢应变速率拉伸实验的方法,以及SEM、TEM等手段研究了不可逆氢陷阱对高强度钢42CrMo和13Ni5CrMoV钢的氢致延迟断裂行为的影响,并分析了其微观组织特征、力学性能与陷阱类型的内在关系。结果表明,相比低碳高镍钢13Ni5CrMoV,中碳钢42CrMo在回火过程中易于形成-Fe_(x)C,并存在大量非共格的不可逆氢陷阱Fe_(3)C。42CrMo钢中不可逆氢陷阱激活能为68.3 kJ/mol。不可逆氢陷阱对42CrMo钢的缺口强度具有一定程度的影响,实验证实了对于缺口部件,其不可逆氢原子转变为可逆氢原子,进而参与HIC过程。充氢对42CrMo钢制光滑试样的强度和塑性具有影响,而其仅降低了13Ni5CrMoV钢的塑性,组织差异带来的陷阱类型、分布,使两种实验钢的HIC性能迥异。结合实验钢的陷阱类型与SSRT拉伸性能,不可逆氢陷阱分布于晶界、板条马氏体间隙,其捕获的氢原子在应力梯度作用下转变为可扩散氢原子,从而在晶界、缺陷处发生富集,进而恶化实验钢的力学性能。

超高强马氏体钢抗氢致延迟开裂性能的研究

超高强马氏体钢易氢致开裂。通过渗氢试验、热脱附试验及动态低应变速率拉伸试验等,研究了具有不同组织的冷轧马氏体钢1号、2号试样的抗氢致延迟开裂性能。1号试样组织为马氏体+铁素体+渗碳体,平均晶粒尺寸为7.0μm;2号试样组织为回火马氏体+渗碳体,平均晶粒尺寸为6.1μm。结果表明:1号试样的表观扩散系数Dap为7.081×10^(-7) cm^(2)/s,2号试样的为4.670×10^(-7) cm^(2)/s;1号试样的可扩散氢含量为0.1923μg/g,明显小于2号试样的0.2605μg/g;2号试样对氢的敏感性大于1号试样;随着充氢电流密度的提高,拉伸试验时1号试样从韧性断裂变为准解理断裂,2号试样则从韧脆性断裂变为穿晶脆性断裂;与1号试样相比,2号试样的氢表观扩散系数和可扩散氢含量均更大;对于超高强钢,除了有效氢陷阱外,减小局部应力也能显著改善抗氢致延迟开裂性能。

两种热轧工艺供料生产的SPCC冷轧钢板组织和抗鳞爆性研究

目前,我国制备热轧钢卷主要采用紧凑热带生产工艺(即钢坯浇铸和热轧紧凑连续生产,简称“CSP工艺”)和常规热轧工艺,不同热轧工艺生产的冷轧钢板组织和性能有明显区别。文中研究了CSP工艺和常规工艺供料生产的冷轧碳钢薄板(亦称SPCC冷轧钢板)的显微组织和抗鳞爆性能,结果表明,CSP工艺供料生产的SPCC冷轧钢晶粒直径为10~15μm,碳化物和MnS晶粒直径为100~200 nm;而常规工艺供料生产的SPCC冷轧钢晶粒直径为20~30μm,碳化物和MnS晶粒直径为500~1 000 nm。CSP工艺供料生产的SPCC冷轧钢晶界面积更大,晶内析出物尺寸小,分布更弥散,且提供了更多的“氢陷阱”,氢渗透时间是常规工艺供料生产SPCC冷轧钢的2倍,因此,CSP工艺供料生产的冷轧钢板搪瓷有较好的抗鳞爆性能。

铜元素对铝硅合金氢陷阱和氢含量影响的研究

氢陷阱的性质和种类与铸态铝硅合金的氢含量密切相关,氢含量又决定合金的性能。通过热解吸光谱及X射线衍射研究铜元素对铝硅合金氢陷阱性质和种类的影响,并结合扫描电镜进一步分析氧化膜与氢含量的关系。研究结果表明,铜元素的添加会提高铸件的位错密度,增大共晶硅相与铝基体的接触面积,导致这两个氢陷阱捕获的氢含量增大,并生成一个新的氢陷阱Al-Al2Cu-Si相。另一方面,铜元素会降低铝硅铸件氧化膜的致密度,促使气体溢出,降低铸件芯部与边部之间的孔隙率和氢含量。

基于中性粒细胞外诱捕网探讨硫化氢对脓毒症心肌病的影响及作用机制

目的:基于中性粒细胞外诱捕网探讨硫化氢(H2S)对脓毒症心肌病的影响及作用机制。方法:采用盲肠结扎穿孔法(CLP)制备脓毒症心肌病模型,将48只SPF级CLP大鼠随机分为假手术组、脓毒症模型组(模型组)、H2S给药(NaHS,内源性H2S供体)组、H2S抑制剂(PAG,内源性抑制H2S剂)组。造模完成后,给药组大鼠通过腹腔注射给药,模型组和假手术组大鼠予以注射等剂量的生理盐水,24h后检测各组大鼠H2S水平,心肌酶指标及病理改变、心肌炎症因子水平、中性粒细胞外诱捕网形成相关因子GSDMD、MPO、CitH3。结果:与假手术组相比,模型组大鼠H2S水平明显降低,心肌损伤更显著,予以腹腔注射硫氢化钠后,相较于模型组,H2S给药组大鼠血清H2S水平增加,且中性粒细胞外诱捕网相关蛋白GSDMD、MPO、CitH3表达减少,炎症因子水平降低,以上改变可被H2S抑制剂逆转。结论:外源性予以H2S可以通过抑制中性粒细胞外诱捕网形成减轻脓毒症心肌病。