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Effect of Hydrogen on Plastic Deformation near Crack-tipof A537 Steel in 3.5%NaCl Solution

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Journal of Materials Science & Technology 1996年第3期12卷 227-231页

作者： wei, XJ Li, J wang, ZF ke, w State key Lab. of Corrosion and Protection Institute of Corrosion and Protection of Metals Chinese Academy of Sciences Shenyang 110015 China

A computerized digital speckle-interferometry system was set up to study in-situ the influence of cathodic hydrogen charging on the crack opening displacement and on the plastic strain distribution at corrosion fatigue crack tip for the single-edge notched plate specimens of structural steel in 3.5%NaCl solution with an applied potential of -1400 mV (SCE). Meanwhile, the mono-directional tension tests with smooth specimens were performed in both air and 3.5%NaCl solution under the hydrogen charging conditions. The fracture surface morphology from corrosion fatigue and tension was examined by SEM. The experimental results show that the existence of hydrogen in crack tip material caused an increase of both yield strength and hardening exponent and a decrease of plastic zone size at the corrosion fatigue crack tip.

关键词： NaCl Effect of Hydrogen on Plastic Deformation near Crack-tipof A537 Steel in 3.5%NaCl Solution SCE

Influence of Inhibitor Concentration on Corrosion Fatigue Crack Initiation and Propagation

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Journal of Materials Science & Technology 1995年第1期11卷 67-70页

作者： wANG, ZF LI, J wANG, JQ ke, w

The paper reports the effect of 0.01, 0.1 and 1%NaNO2, a passive inhibitor, on corrosion fatigue (CF) crack initiation and propagation for a low strength structural steel A537 in 3.5%NaCl aqueous solution. The experimental results show that inhibitor increases the required cycles of CF crack initiation effectively, and this effect increases with increasing inhibitor concentration. However, there is nearly no effect of NaNO2 on CF crack propagation. The same CF crack propagation rate was found in all kinds of solutions. The results also indicate that the passive time in 1%NaNO2 solution during plastic deformation is much longer than cyclic time. NaNO2 passivates the specimen surface and repairs passive film damaged by cyclic loading during the crack initiation, while the passsive film is not formed fully due to continuous plastic deformation at the crack tip during the CF crack propagation, which is much different from that in the stress corrosion cracking and general corrosion.

关键词： Figure Influence of Inhibitor Concentration on Corrosion Fatigue Crack Initiation and Propagation

Corrosion Evolution of Reinforcing Steel in Concrete under Dry/wet Cyclic Conditions Contaminated with Chloride

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Journal of Materials Science & Technology 2012年第10期28卷 905-912页

作者： J.wei X.X.Fu J.H.Dong w.ke State key Laboratory of Corrosion and Protection Institute of Metal ResearchChinese Academy of SciencesShenyang110016~China

The corrosion evolution of rebar in concrete was monitored by electrochemical impedance spectroscopy （EIS） under dry/wet alternated accelerated corrosion test. Four stages with different dynamic characteristics were observed during the corrosion evolution. They were passive stage, local corrosion controlled by the charge transfer step, accelerated corrosion controlled by the mass transfer step, and constant rate corrosion controlled by the mass transfer step through a barrier layer. X-ray diffraction （XRD） analysis showed that the corrosion product of rebar in mortar was composed of α-FeOOH, γ-FeOOH and Fe304. The corrosion mechanisms of all four stages were discussed and the corrosion reactions were proposed according to the corrosion product and corrosion evolution characteristics.

关键词： Rebar Concrete Electrochemical impedance spectroscopy (EIS) Corrosionevolution

Short-time Oxidation of Alloy 690 in High-temperature and High-pressure Steam and water

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Journal of Materials Science & Technology 2012年第6期28卷 562-568页

作者： F.Huang J.Q.wang E.H.Han w.ke State key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The oxidation behavior of alloy 690 exposed to high-temperature and high-pressure steam and water at 280℃ for 1 h was investigated by scanning electron microscopy （SEM）, atomic force microscopy （AFM） and X-ray photoelectron spectroscopy （XPS）. In high-temperature and high-pressure steam, the oxide film is composed of an outermost Ni-rich hydroxides layer, an intermediate layer of hydroxides and oxides enriched in Cr, an inner oxide layer. The film formed in high-temperature water is similar to that in steam, except for missing the Ni-rich hydroxides layer. Samples with different surface finishes （electropolished, mechanically polished, ground, and as-received） were prepared for comparison. A general increase of the oxide thickness with the degree of surface roughness is observed. The equivalent oxide thicknesses lie in the range of 100-200 nm for the as-received samples, 150-250 nm for the samples ground to 400# and 10-20 nm for the samples ground to 1500#, mechanically polished, and electropolished.

关键词： Alloy 690 Oxidation High-temperature water Surface finish X-ray photoelectron spectroscopy (XPS)

Effect of corrosion product films on the in vitro degradation behavior of Mg-3%Al-1%Zn(in wt%) alloy in Hank's solution

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Journal of Materials Science & Technology 2018年第10期34卷 1756-1764页

作者： B.J.wang D.K.Xu J.H.Dong w.ke School of Environmental and Chemical Engineering Shenyang Ligong University CAS key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Environmental Corrosion Center Institute of Metal Research Chinese Academy of Sciences

Through investigating the corrosion behavior of an as-extruded Mg-3wt%gAl-lwt%Zn （AZ31） alloy in a simulated physiological fluid of Hank＇s solution, it demonstrates that the corrosion process was depen- dent on the immersion time. Further analyses revealed that the highest corrosion resistance could be obtained at 24 h due to the formation of a compact layer of corrosion products on the sample surface. with increasing the immersion time to up to 48 h, the thickness of surface films increased gradually but obvious de-bonding of such film from the substrate could take place, resulting in a certain resilience of the overall corrosion resistance.

关键词： Magnesium Surface layer Corrosion product Interface

Effect of grain refinement on the hydrogen embrittlement of 304 austenitic stainless steel

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Journal of Materials Science & Technology 2019年第10期35卷 2213-2219页

作者： Y.H.Fan B.Zhang J.Q.wang E.-H.Han w.ke Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China CAS key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The effect of grain size(in the range from 4 μm to 12 μm) on the hydrogen embrittlement(HE) of 304 austenitic stainless steel(ASS) was studied. HE susceptibility result shows that HE resistance increases with grain refinement. Electron backscattered diffraction kernel average misorientation(EBSD-KAM)mapping shows that the strain localization can be mitigated by grain refinement. Hence, strain localization sites which act as highways for hydrogen diffusion and preferred crack initiation sites can be reduced along with grain refinement, leading to a high HE resistance. Meanwhile, grain size shows no influence on the strain induced martensite(SIM) transformation during the hydrogen charging slow strain tensile test(SSRT). Hence, the SIM formed during hydrogen charging SSRT is not responsible for the different HE resistance of 304 ASSs with various grain sizes. Hydrogen diffusion is supposed to be controlled by a competition between short-circuit diffusion along random grain boundary(RGB) and hydrogen trapping at dislocations, leading to a maximum hydrogen diffusion coefficient in the 304 ASS with an average grain size of 8 μm.

关键词： Stainless steel Grain refinement Hydrogen embrittlement SEM EBSD

Influence of grain size on the tensile ductility and deformation modes of rolled Mg–1.02 wt.%Zn alloy

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Journal of Magnesium and Alloys 2013年第3期1卷 210-216页

作者： B.Q.Shi R.S.Chen w.ke State key Laboratory for Corrosion and Protection Institute of Metal ResearchChina The University of the Chinese Academy of Sciences Beijing 100049China

The influence of grain size on the tensile deformation and ductility for Mg–1.02%Zn(wt.%)alloy was *** uniform elongation is nearly insensitive to the increase of grain size,but the post-uniform elongation is significantly decreased with increasing grain *** high ductility in the fine-grained samples is due to the lower frequency of twins and increased dynamic recovery from the enhanced activation of prismaticslip.

关键词： Magnesium Ductility Texture Strain hardening rate Prismatic slip

INVESTIGATION OF INFLUENCE OF HYDROGEN ATTACK ONFATIGUE PROPERTIES OF PRESSURE VESSEL STEELS

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Acta Metallurgica Sinica(English Letters) 1998年第2期11卷 141-149页

作者： J.L.Li K.F.wang J.Li Z.M.Yao w.ke Fushun Petroleum Inst Fushun China

Influence of hydrogen attack on mechanical and fatigue properties of 1020, 15CrMo and 2.25Cr-1Mo steels has been studied, which were exposed to gaseous hydrogen at pressure of 18MPa and 300-480℃ for up to 480h. The results of fatigue test showed that hydrogen attack (HA) resulted in an obvious change in fatigue properties of 1020 and 15CrMo steels, however, 2.25Cr-1Mo steel showed a lower susceptibility to hydrogen attack due to the addition of Cr and Mo. Fatigue crack behaviour for 1020 steel is attributed to hydrogen attack damage and the crack closure induced by the rough cracking surface, which lead to a valley on △Kth～HA% plot. The change in the fatigue behaviour of 15CrMo steel is possibly caused by severe surface decarburization.

关键词： hydrogen attack pressure vessel steel threshold △K value crack closure

Effect of pre-induced twinning on microstructure and tensile ductility in Gw92K magnesium alloy during multi-direction forging at decreasing temperature

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Journal of Magnesium and Alloys 2014年第4期2卷 287-292页

作者： S.Q.Li w.N.Tang R.S.Chen w.ke The Group of Magnesium Alloys and Their Applications Institute of Metal Research Chinese Academy of Sciences62 Wencui RoadShenyang 110016China

Effect of pre-induced twinning on the microstructure evolution and mechanical properties of extruded Mg-9.26Gd-2.08Y-0.36Zr(Gw92K)alloy have been investigated during multi-direction forging with large strains at decreasing temperature from 400℃ to 300℃.The results showed that,whether there pre-induced twinning existing in the initial microstructure by pre-deformation or not,a mixed microstructure of residual coarse grains and notably refined grains formed under both conditions,combing with some residual coarse grains with less deformation inside grains and lots of dispersed nano-precipitates distributed along refined grain ***,a significant improvement with the tensile ductility was obtained by the pre-induced twinning in the former *** was suggested that,the pre-induced twinning largely contributed to the grain refinement and lead to an increase in the ratio of fine grain structure which would be responsible for the better ***,during subsequent forging deformation in the pre-deformed sample,the grain refinement mechanism by gradual grain orientation rotation around the surface section in residual coarse-grains was a little different from that by the macro-shear deformation in the as-extruded condition.

关键词： Magnesium alloy Pre-induced twinning Multi-directional forging Refined-grain microstructure Tensile ductility