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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

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

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

Atom probe tomographic observation of hydrogen trapping at carbides/ferrite interfaces for a high strength steel

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Journal of Materials Science & Technology 2018年第8期34卷 1344-1348页

作者： Y.F.Jiang B.Zhang Y.Zhou J.Q.wang E.-H.Han w.ke CAS key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

A three-dimensional atom probe （3DAP） technique has been used to characterize the hydrogen dis- tribution on carbides for a high strength AISI 4140 steel. Direct evidence of H atoms trapped at the carbide/ferrite interfaces has been revealed by 3DAP mapping. Hydrogen is mainly trapped on car- bide/ferrite interfaces along the grain boundaries. Slow strain rate tensile （SSRT） testing shows that the AIS14140 steel is highly sensitive to hydrogen embrittlement. The corresponding ffactographic mor- phologies of hydrogen charged specimen exhibit brittle fracture feature. Combined with these results, it is proposed that the hydrogen trapping sites present in the grain boundaries are responsible for the hydrogen-induced intergranular fracture of AISI 4140. The direct observation of hydrogen distribution contributes to a better understanding of the mechanism of hydrogen embrittlement.

关键词： Low alloy steel TEM Interfaces Hydrogen embrittlement

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

Effect of heat treatment on the microstructures and mechanical properties of the sand-cast Mg-2.7Nd-0.6Zn-0.5Zr alloy

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Journal of Magnesium and Alloys 2014年第1期2卷 20-26页

作者： D.wu Y.Q.Ma R.S.Chen w.ke The Group of Magnesium and Their Applications Institute of Metal ResearchChinese Academy of Sciences62 Wencui RoadShenyang 110016China

The tensile testing bars of the Mg-2.7Nd-0.6Zn-0.5Zr(wt.%)alloy were prepared by sand *** effect of solution temperature and aging time on the microstructures and mechanical properties were *** as-cast alloy was composed ofαmagnesium matrix and Mg12Nd eutectic *** solution treatment at 500℃ for 18 h,the volume fraction of eutectic compounds decreased from∼7.8%to∼2.3%,and some small Zr-containing particles were observed to precipitate at grain *** the solution temperature increased to 525℃ for 14 h,most of the eutectic compounds dissolved into the ***-aged at 200℃ for 12 h,fineβ″particles was the dominant strengthening *** yield strength,ultimate tensile strength and elongation in the peak-aged condition were 191 MPa,258 MPa and 4.2%,***,the Mg-2.7Nd-0.6Zn-0.5Zr alloys under different heat treatment conditions exhibited different tensile fracture modes.

关键词： Magnesium alloy Sand-cast Heat treatment Microstructure Mechanical properties

High cycle fatigue behavior of the forged Mg-7Gd-5Y-1Nd-0.5Zr alloy

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Journal of Magnesium and Alloys 2014年第4期2卷 357-362页

作者： D.wu S.Q.Li M.Hong R.S.Chen E.H.Han w.ke The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of Sciences62 Wencui RoadShenyang 110016China Shenyang Aerospace University Shenyang 110036China

This paper investigated the high cycle fatigue behavior of a forged Mg-7Gd-5Y-1Nd-0.5Zr alloy with different stress concentration factor(Kt),under different stress ratio(R),and along different loading *** smooth specimen(Kt=1),under R=0.1 and along longitude direction,shows a high fatigue strength of 162 MPa at 107 *** fatigue behavior of the forged Mg-7Gd-5Y-1Nd-0.5Zr alloy exhibits a high sensitive to the ***,change of stress ratio from 0.1 to−1 may also result in a bad fatigue *** flux inclusions were elongated along longitude direction and/or transverse direction during the forging process of the Mg-7Gd-5Y-1Nd-0.5Zr *** interface between the flux inclusion and the matrix may debond and serve as the crack initiation site during the fatigue loading process,leading to the deterioration of the fatigue property along thickness direction and a high anisotropic fatigue behavior between longitude direction and thickness direction.

关键词： Magnesium alloy Forge High cycle fatigue Stress ratio Inclusion