塑性形变对4340钢中氢的富集及传输行为影响

采用渗氢试验和数值计算两种方法研究．了塑性形变对金属中氢的扩散和富集的影响，讨论了４３４０钢中的氢浓度与塑性形变大小、氢扩散时间及边界条件之间的关系．     

30CrMnSiNi2钢TIG焊接头电化学充氢后扩散氢逸出特征及示踪

高强度钢焊接接头不同区域组织对氢扩散与聚集的影响存在差异,采用显微镜摄影测氢法研究了电化学充氢条件下,30CrMnSiNi2钢TIG焊接头不同区域扩散氢的逸出规律,观察了氢气泡大小及分布特征;采用氢原子微印技术对焊缝区的扩散氢进行了示踪研究,探讨了高强度钢焊接头扩散氢逸出分布特征与低碳钢完全相反的原因,结果表明,30CrMnSiNi2A钢TIG焊接头扩散氢主要聚集在焊缝区及热影响区,焊缝区亚晶界为氢扩散和聚集的优先通道,组织中的内应力场是导致扩散氢聚集的根本原因. 研究结果对于研究焊接接头不同区域组织与扩散氢的关系提出了有益的思路.     

热浸镀铝钢氢的扩散

根据费克第二定律提出了热浸镀铝钢双层体系氢扩散系数解法.根据上述结果,用电化学方法测定了氢的扩散行为;测定了渗铝层不同温度下氢的扩散系数和渗铝层氢扩散激活能.     

X80管线钢焊接接头氢分布的数值模拟

利用ABAQUS有限元软件,建立了三维有限元模型,对X80管线钢焊接接头的氢扩散行为进行了模拟. 通过对不同焊接条件下温度场、应力场、氢扩散的三场耦合模拟,研究了焊接工艺参数对焊接接头中氢扩散及分布的影响. 结果表明,焊接热影响区残余应力水平最高,是整个接头的应力集中部位,也是焊接接头中的富氢地带. 适当地提高预热温度和焊接热输入,均有利于焊接接头中氢的扩散逸出,降低氢在焊接热影响区的聚集程度,从而降低氢致裂纹的敏感性.     

铌微合金化对系泊链钢氢脆敏感性的影响

金属的氢脆敏感性与氢在其中的扩散密切相关,添加适量的铌能显著降低钢的氢脆敏感性.采用电化学氢渗透试验、动态充氢拉伸试验研究了氢在不含铌和含0.03％、0.05％和0.08％Nb(质量分数)的高强度低合金系泊链钢中的扩散行为及Nb含量对钢的氢脆敏感性的影响.结果表明:随着Nb的质量分数从0增加到0.05％,氢在钢中的扩散...     

氢在20g纯净钢中的扩散研究

用双电解池氢渗透方法研究了20g纯净钢中缺陷对氢扩散的影响.实验结果表明:新鲜试样氢渗透曲线中氢的穿透时间最长,而氢渗透实验后未经处理的试样再次氢渗透实验时的氢穿透时间最短,这是由于钢中氢陷阱滞后了氢原子从试样的阴极面扩散至阳极面的时间所致.时间滞后法的计算结果表明,20g纯净钢中的氢陷阱严重降低了氢的表观扩散系数.     

高强度钢焊缝金属氢控制研究进展

综述了对高强度钢焊接接头氢控制的现有方法,重点总结了高强度钢焊缝金属氢控制方面的一些研究进展.包括:选择合适的焊缝金属马氏体的转变温度,可以有效地促进氢向母材扩散,进而降低氢致裂纹的危险;高强度钢焊缝金属中不可避免存在的一定量的残余奥氏体,虽然有固化氢的作用,但在低温或受外力作用时转变成马氏体,成为对氢致裂纹敏感的组织;利用钕钇等稀土元素在焊缝组织中制造强氢陷阱,可以固化大量的氢,从而减少焊缝金属中的扩散氢;焊接熔渣的溶氢能力的提高,可以减少氢向焊缝金属的分配,从而降低焊缝金属的扩散氢.     

熔渣的溶氢能力与熔敷金属的扩散氢

分别改变碱性焊条熔渣中CaO和Mgo与气保护药芯焊丝熔渣中Al2O3和MgO组元的相对含量,研究其对熔敷金属扩散氢的影响.结果表明,碱性焊条熔渣中,用同等质量MgO取代CaO导致熔敷金属扩散氢大幅度提高;药芯焊丝焊接熔渣中,脱氧产物若不是以Al2O3为主而是以MgO为主,熔敷金属扩散氢则大幅度提高.分析认为,熔渣成分的变化导致其溶氢能力的变化是这一结果的主要因素,即Ca2 离子导致熔渣含氧量的提高及氢在Al2O3中具有较高的溶解度等提高了熔渣的溶氢能力.     

氢在钢铁表面吸附以及扩散的研究现状

氢进入钢铁内部是其发生氢脆的前提,而氢在管线钢表面经历物理吸附、解离、化学吸附、扩散一系列过程才能进入管线钢内部,其中氢原子的化学吸附以及氢扩散是关键步骤。综述了氢在钢铁表面吸附、扩散的研究方法、成果,展望了氢吸附以及氢扩散的研究方向。目前研究氢吸附的主流方法是第一性原理计算。在氢扩散研究方面,试验研究能够分析钢铁组织、相、宏观尺度因素变化对氢扩散的影响;有限元、分子力学、第一性原理多种尺度模拟计算可以分析微区结构变化对扩散的影响。氢在表面的吸附以及表层原子的扩散对氢脆有重要影响,但氢原子在钢铁表面的吸附以及表层扩散主要集中在无缺陷的αFe表面。氢与缺陷的相互作用研究主要集中在体相内部,钢铁表面状态的变化对氢吸附以及表层扩散的影响相关报道较少。需进一步开展在含缺陷钢铁表面的氢吸附研究,阐释表面应力、位错、晶界、相界、合金元素等因素对氢吸附、表层区域氢扩散的影响机理。     

高强钢焊接接头扩散氢行为研究

针对900 MPa钢级高强钢,采用甘油法测试焊接接头中扩散氢含量,并研究焊后放置72 h内扩散氢的逸出规律.研究结果表明,试板装瓶后0.5～12 h时,扩散氢的逸出速度很快,逸出量比较大,可以达到总逸出量的90％;在12～24 h这一时间区间内,扩散氢逸出速度变慢;在24～72 h时间内,扩散氢逸出量基本维持不变.由此看出,在焊接后24 h内,熔敷金属中的扩散氢已经逸出怠尽.本研究结果也表明对高强钢焊接结构进行消氢处理时必须在焊后尽快进行,否则消氢处理的意义不大.     

Hydrogen permeation behavior of nickel electroplated AISI 4340 steel

The role of the electroplated nickel layer on hydrogen permeation through AISI 4340 steel was investigated by a electrochemical hydrogen permeation test. The permeation test, composed of three steps, was conducted to measure the hydrogen diffusivity and surface hydrogen concentration. A constant current of 20 mAcm^-2 and a constant potential of -100 mV vs. Ag/AgCl electrode were applied to the hydrogen entry and exit cells, respectively. The thickness of the electroplated nickel layer on AISI 4340 steel increased in a linear fashion with an increase in electroplating time. The nickel coated layer contributed to a decrease in the hydrogen permeability of nickel coated AISI 4340 steel specimens. This is due to the fact that the surface hydrogen concentration and hydrogen diffusivity in nickel coated layer were lower than those of AISI 4340 steel substrate. Especially, low hydrogen diffusivity decreased significantly with hydrogen permeability. The critical effective hydrogen diffusivity for barrier of nickel electroplated AISI 4340 steel specimens was higher than the hydrogen diffusivity of AISI 4340 steel specimen. It is proposed then that the thin nickel layer on AISI 4340 steel acts as a barrier for hydrogen permeation through AISI 4340 steel.     

渗铝钢的抗氢损伤性能

采用钝化助镀法在30CrMo钢表面获得热浸铝层,通过扩散渗铝和调质处理获得了渗铝钢试片和试棒.用氢渗透电化学技术测量了渗铝钢在饱和H2S盐水中的渗氢曲线,得到了不同温度(T)下氢在渗铝钢中的扩散系数(D),拟合得到了T与D的关系式,并研究了溶液中NaCl和CO2对稳态氢渗透电流(Imax)的影响.比较了30CrMo渗铝钢在饱和H2S盐水中腐蚀前后的机械性能.结果表明：热浸渗铝钢对氢扩散有明显的阻滞作用,其抗氢损伤性能好于基体钢材.     

Erosion-corrosion behavior and cathodic protection of alloys in seawater-sand slurries

An experimental study was conducted on the erosion-corrosion behavior of three alloys in seawater-sand slurries. The idea explored was to select a steel, a copper alloy, and a titanium alloy, which should have good resistance to abrasive wear because of high hardness (within their alloy classes). Then cathodic pro-tection would be used to protect them from corrosion. The alloys studied were 4340 steel, silicon bronze, and titanium alloy Ti-6V-4Al. Limiting conditions for cathodic protection were derived from electro-chemical polarization measurements. From erosion-corrosion tests, it was found that erosive wear by sand dominated the metal loss rates of both silicon bronze and Ti-6V-4Al. For the 4340 steel, which was the hardest material, cathodic protection provided good erosion-corrosion resistance. Supplementary measurements showed that ductility loss due to cathodically charged hydrogen in the 4340 steel was neg-ligible under the experimental conditions.     

20g纯净钢中氢陷阱对氢扩散系数的作用

对理想晶体中的H扩散通量与充H时间的关系式进行修正,并用修正后的公式直接从实验数据中拟合H在材料中的扩散系数和穿透时间,结果表明,用理想晶体中H扩散通量随充H时间变化的修正关系式可以表征实际材料在电化学充H过程中的H原子扩散通量随充H时间变化的关系曲线,也可以用以研究实际材料中H陷阱对H原子扩散系数的作用.用修正后的公式对20g纯净钢电化学充H实验数据进行最小二乘法拟合,直接得到H原子在不同H陷阱状态20g纯净钢中的扩散系数和穿透时间.拟合结果显示:20g纯净钢中的不可逆H陷阱对H原子的扩散系数没有影响,只是延长了H原子的穿透时间,而可逆H陷阱则降低了H原子的扩散系数.     

Electrodeposition of Zn–Ni coatings as Cd replacement for corrosion protection of high strength steel

Electrodeposition of Zn–Ni coatings performed in acidic baths are not suitable for high strength steels due to their high susceptibility to hydrogen embrittlement.In this work, Zn–Ni coatings were deposited on a high strength steel (4340) upon stirring conditions from an alkaline bath. A complete characterisation of the coatings (corrosion, morphology and composition) has been accomplished, correlating the electrodeposition conditions with these features. The best protective properties of the grown coatings were achieved for the alloys with a single phase structure of γ-Ni₅Zn₂₁ and a denser morphology. Additionally, the hydrogen content incorporated is lower than even cadmium-coated 4340 steel which has undergone a postbaking dehydrogenation treatment.     

1500 MPa级40CrNi3MoV钢的氢脆敏感性

通过慢应变速率拉伸实验研究了Si含量分别为0.25%和1.16%的1500 MPa级40CrNi3MoV钢的氢脆敏感性,即充氢后缺口试样抗拉强度下降率,冲击实验用来测试1 mA/cm2电流密度下充氢后试样的断裂韧性值,分析氢致裂纹的扩展方式.结果表明,由于Si抑制回火过程中碳化物的形核和长大,高Si含量的40CrNi3MoV钢中回火析出的碳化物被细化且弥散分布,作为氢陷阱使氢分布均匀,抑制了氢向裂纹尖端扩散,高Si含量的40CrNi3MoV钢的氢脆敏感性较低.     

EFFECT OF MICROSTRUCTURE ON HYDROGEN DAMAGE OFJBK-75 PRECIPITATE-STRENGTHENED AUSTENITIC STEEL

1.IntroductionHydrogenembrittlement(HE)0rhydr0gendamage(HD)ofall0ysisnotonlyrelatedt0chemicalc0mpositionsbutals0c10selyt0microstructures.Thereweres0merep0rts0ntheeffect0fmicr0structures0nHD0fsingle-phaseausteniticsteels[1-3].Themicrostructuralreas0nsofHD0fprecipitate-strengthenedausteniticsteels(PSAS),however,havereceivedlessattenti0n.Single-phaseausteniticsteelshaveproveninseveralinstancestohaveg00dresistancet0HD,butaretypicallynostr0ngerthan450MPainyieldstrength.Thus,anausteniticmatri…     

INVESTIGATION OF INFLUENCE OF HYDROGEN ATTACK ON FATIGUE PROPERTIES OF PRESSURE VESSEL STEELS

1.IntroductionLowalloysteelsexposedtohydrogenatmoderatepressuresandtemperaturessufferalossinmechanicalandfatigueproperties.Thisphenomenon,calledhydrogenattack(HA)['],isduetothemethanegeneratedbychemicalreactioll:abC. 2H2~ac ACHe.Methaneformationmayoccureitheratafreesurface(surfacedecarburization)oratinternalsiteinthemetal(internaldecarburiatioll)suchasgrainboundariesanddefects.Internalmethaneisunabletodiffuseoutofthesteel,anditmaybllildupintheinterllalvoidsandgrainboundaries,growandcoalesce…     

INFLUENCE OF INTERNAL HYDROGEN ON THE HYDROGEN EMBRITTLEMENT OF AUSTENITIC STAINLESS STEEL

1.IntroductionManyengineeringstructure8maybeaffectedbyhighpressurehydrogenafteral0ngtimesuchashydrogen-st0ragepressurevessel/hydrogen-transportpiping/highpressurehy-drogenpurificationandpressurizati0nequipment.Thesafetyofthesestructuresmaybedecreasedbecau8eofhydrogenembrittlementcausedbytheinteracti0nbetweenthestruc-turalmaterialandhydr0genresultinginlossofductilityinthematerial-Manyresearchersareinterestedinthestudyofhydrogenembrittlement0fmaterials,especiallytheausteniticstainlesssteel,andha…