LI Hiaogang
,
MENG Qinghai
,
CHEN Hua
,
CHEN Jinwei
,
YAO Zhiming
,
KE Wei(State Key Laboratory of Corrosion Science
,
Institute of Corrosion and Protection of Metals
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)(Fushun Petroleum Institute
,
Fushun 113001
,
China)
金属学报(英文版)
Hydrogen attack occurred in low carbon steel and steel 25CrMo which had been exposed in hydrogen under 18MPa at 450 and 500℃ for 240,480 and 720 h.The methane bubbles and microcracks grow along grain boundaries.The degree of hydrogen attack increases with increasing exposure time and temperature.Magnetic acoustic emission(MAE) was used to detect the degree of hydrogen attack.The results show that the characteristics of MAE for samples of low carbon steel and steel 15CrMo with hydrogen attack have changed obviously comparing to the samples without hydrogen attack,and the MAE signals was sensitive to the degree of hydrogen attack at the last stage of hydrogen attack.The magnetic detection way,as a new method of nonrestrictive testing of hydrogen attack,can be used to detect the hydrogen attack in practice.
关键词:
:magnetic acoustic emission
,
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,
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,
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Corrosion
The corrosion products formed on carbon steel exposed to the Qinghai Salt Lake atmosphere for 12 months was studied using scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), x-ray diffraction (XRD), infrared transmission spectroscopy (IRS), and electrochemical techniques. The rust was mainly composed of akagarteite (beta-FeOOH), iron hydroxychloride (Fe(8)[O,OH](16)Cl(1.3)), and a little lepidocrocite (gamma-FeOOH). Amorphous (delta-FeOOH was only on the downward surface, and the upward surface was corroded more severely than the downward surface. Cl. Mg, and Si foreign elements were rich in the rust. The rust on carbon steel decreased anodic dissolution and increased cathodic current. A low free corrosion potential of the rusted electrode and a very small value of rust resistance (R(R)) demonstrated that the rust was nonprotective in the Qinghai Salt Lake atmosphere.
关键词:
atmospheric corrosion;carbon steel;salt lake
Chinese Science Bulletin
The rusts formed on carbon steel and weathering steel exposed in Qinghai Salt Lake atmosphere for 6 months were characterized by X-ray diffraction (XRD), infrared transmission spectroscopy (IRS), scanning electron microscopy (SEM), electron probe micro analyzer (EPMA) and electrochemical polarization techniques. The two kinds of steels showed the similar corrosion rate, corrosion product composition and electrochemical polarization behavior. Their rusts were mainly composed of beta-FeOOH, Fe(8)(O,OH)(16)Cl(1.3) and a little gamma-FeOOH. Cl(-) played an important role during the corrosion process of low-alloyed steels. The alloyed elements Cr, Ni and Cu in weathering steel were detected in the rusts; however, they showed no remarkable protective ability.
关键词:
atmospheric corrosion;carbon steel;weathering steel;XRD;EPMA;weathering steels;carbon-steel;rust;mechanism;corrosion;iron
Materials Chemistry and Physics
The corrosion behaviour of CortenA weathering steel has been investigated using a laboratory accelerated test that involved cyclic wet/dry conditions in Qinghai salt lake water diluted 30 times The characteristics of the rust layers on tested samples were observed by SEM and EPMA analyzed by IRS and XRD and studied by polarization and EIS measurements The weight loss was almost linear indicating that the rust layer had no retarding effect on the corrosion process The crystalline components of the rust layers consisted primarily of beta-FeOOH magnetite (Fe(3)O(4)) and gamma-FeOOH As the corrosion proceeded the amount of beta-FeOOH decreased while that of magnetite and gamma-FeOOH increased XRD EDAX and EPMA indicated that the complex corrosion products magnesioferrite (MgFe(2)O(4)) and iowaite (Mg(4)Fe(OH)(8)OCl 4H(2)O) probably existed in the rust layer in which case they will have had an important Influence on the protectiveness of the rust layer The results of electrochemical measurements showed that the rust layer exhibited high reduction reactivity which facilitated the corrosion of weathering steel in the wetting process The large rust capacitance and small rust resistance indicated that the rust layer had a loose and porous structure which provided poor protection (c) 2010 Elsevier B V All rights reserved
关键词:
Elements;Corrosion test;Electrochemical techniques;Electron probe;low-alloy steels;atmospheric corrosion;carbon-steel;electrochemical;impedance;room-temperature;rust layers;iron;mechanism;products;environment
Corrosion Science
The product formed oil weathering steel exposed to salt lake atmosphere for 12 months was investigated by X-ray diffraction (XRD), infrared transmission spectroscopy (IRS), scanning electron microscopy (SEM), electron probe micro analyzer (EPMA) and electrochemical techniques. The rust was mainly composed of beta-FeOOH, Fe(8)(O,OH)(16)Cl(1.3) and a little gamma-FeOOH. Amorphous delta-FeOOH was only oil skyward surface. The rust layer suppressed anodic reaction and facilitated the cathodic reaction. The very small value of rust resistance R(r) in this work indicated that the rust had poor protective ability. Cl element was rich in the whole rust layer and played an important role in accelerating the corrosion of weathering steel in salt lake atmosphere. (C) 2007 Elsevier Ltd. All rights reserved.
关键词:
weathering steel;atmospheric corrosion;salt lake;plain carbon-steel;low-alloy steels;industrial environments;corrosion;behavior;mechanism;marine;iron
