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Investigation of stress corre-sion cracking under anodic dissolution control

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Chinese Science Bulletin 2001年第9期46卷 717-722页

作者： Wuyang chu Lijie Qiao kewei gao Univ Sci & Technol Beijing Dept Mat Phys Beijing 100083 Peoples R China

This review is about stress corrosion cracking (SCC) under anodic dissolution control. The section 1 is the methods distinguishing SCC controlled by anodic dissolution from those by hydrogen. The section 2 presents hydrogen-enhanced corrosion and SCC under anodic dissolution control. The section 3 demonstrates corrosion-enhanced localized plasticity and corrosion-induced deformation localization, which are the fundaments of new mechanism of SCC. The section 4 is an overview of the proposed mechanisms of SCC under anodic dissolution control. The last section proposes a new mechanism of SCC.

关键词： stress corrosion cracking hydrogen induced cracking dislocation.

Effect of Hydrogen on Dezincification Layer-Induced Stress

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Journal of Materials Science & Technology 2003年第3期19卷 287-288页

作者： Wuyang chu, kewei gao, Yapin LIU Lijie QIAODepartment of Materials Physics, University of Science and Technology Beijing, Beijing 100083, China Dept. of Mat. Phys. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The effect of hydrogen on the dezincification layer-induced stress and the susceptibility to SCC was investigated. Experimental results showed that the dezincification layer-induced stress increased with increasing hydrogen concentration, and 3x10-6 hydrogen could increase the susceptibility to SCC of brass in ammonia solution by 10%.

关键词： Brass Dezincification layer-induced stress Susceptibility to SCC Hydrogen

An investigation of corrosion-induced stress during SCC

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Journal of University of Science and Technology Beijing 2003年第1期10卷 1-7页

作者： Wuyang chu, kewei gao, Lijie Qiao, and Yue ZhangDepartment of Materials Physics, University of Science and Technology Beijing, Beijing 100083, China Univ Sci & Technol Dept Mat Phys Beijing 100083 Peoples R China

TEM (Transmission Electron Microscope) observations show that corrosion process during stress corrosion cracking (SCC) enhances dislocation emission and motion; and microcrack of SCC initiates when the corrosion-enhanced dislocation emission and motion reaches a certain condition. The passive film or dealloyed layer formed during corrosion or SCC can induce a large tensile stress, which can assist the applied stress to enhance dislocation emission and motion, and then SCC occurs. Experiments show that the variation of SCC susceptibility of brass,α-Ti and stainless steel with the applied potential and pH value of the solution is consistent with that of the corrosion-induced additive stress. Molecular dynamics simulations show that a dealloyed layer can generate a tensile stress; and the corrosion (dealloyed layer)-induced tensile stress can assist the applied stress to enhance dislocation emission and crack propagation.

关键词： stress corrosion cracking dislocation emission and motion corrosion-induced stress molecular dynamic simulation

Stress Corrosion Cracking and Passive Film-inducedTensile Stress in α-Ti

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Journal of Materials Science & Technology 2001年第4期17卷 413-416页

作者： Hong LU kewei gao, Hui LIU Lijie QIAO and Wuyang chu Dept. of Materials Physics, University of Science and Technology Beijing, Beijing 100083, China Dept. of Mat. Phys. Univ. of Sci. and Technol. Beijing Beijing 100083 China

α-Ti foil with a protective layer formed on one side was deflected during corrosion in a methanol solution containing 0.6 mol/L KCI and then a tensile stress was generated at or near the metal passive film interface. The in situ TEM observation showed that corrosion process could facil- itate dislocation emission and motion. Adding 10% H2O into the methanol solution decreased the passive film-induced stress from 320 MPa to zero, and the susceptibility to SCC measured in slow strain rate tests decreased correspondingly from 98% to zero.

关键词： Ti Stress Corrosion Cracking and Passive Film-inducedTensile Stress in SCC

Initiating,growing and cracking of hydrogen blisters

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Chinese Science Bulletin 2005年第17期50卷 1962-1965页

作者： REN Xuechong SHAN Guangbin chu Wuyang SU Yanjing gao kewei QIAO Lijie JIANG Bo CHEN Gang CUI Yinhui Department of Materials Physics University of Science and Technology Beijing Beijing 100083 China Technology Center of Ma'anshan Steel & Iron Corporation Ma'anshan 432000 China

The growing process of a hydrogen blister in a wheel steel was observed in situ with an optical microscope, and the fracture surfaces formed from broken blisters on a wheel steel and bulk metallic glass were investigated. The initiating, growing, cracking and breaking of hydrogen blis-ters are as follows. Supersaturated vacancies can increase greatly during charging and gather together into a vacancy cluster (small cavity). Hydrogen atoms become hydrogen molecules in the vacancy cluster and hydrogen molecules can stabilize the vacancy cluster. The small cavity becomes the nucleus of hydrogen blister. The blister will grow with enter-ing of vacancies and hydrogen atoms. With increasing hy-drogen pressure, plastic deformation occurs first, the hydro-gen blister near the surface extrudes, and then cracks initiate along the wall of the blister with further increasing hydrogen pressure. A cracked blister can grow further through propa-gating of cracks until it breaks.

关键词：氢水泡初始过程生长过程破裂过程光学纤维

应力和电场单独或耦合作用下PZT-5H卸载压痕裂纹的扩展

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金属学报 2005年第7期41卷 708-712页

作者：赵显武褚武扬宿彦京高克玮乔利杰北京科技大学材料物理与化学系北京100083

研究了不同极化状态下PZT-5H铁电陶瓷压痕裂纹在应力和电场单独作用以及耦合作用下的扩展行为结果表明, 压痕裂纹残余应力引起的应力场强度因子近似等于断裂韧性.对沿长度方向极化的试样,正、负电场均能引起压痕裂纹的扩展,但正电场的... 详细信息

研究了不同极化状态下PZT-5H铁电陶瓷压痕裂纹在应力和电场单独作用以及耦合作用下的扩展行为结果表明, 压痕裂纹残余应力引起的应力场强度因子近似等于断裂韧性.对沿长度方向极化的试样,正、负电场均能引起压痕裂纹的扩展,但正电场的作用更大.电场和应力的耦合作用表现为对应力的线性叠加.电场引起的内应力σin=(?)YE/[1.16(1-v2)Ec],式中(?)=(2.75=5.71)×10-4,与PZT的极化状态有关.

关键词： PZT铁电陶瓷压痕裂纹应力和电场耦合

浸蚀促进BaTiO_3单晶的畴变和裂纹扩展的研究

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金属学报 2005年第3期41卷 297-301页

作者：王瑞敏褚武扬宿彦京高克玮乔利杰北京科技大学材料物理系北京100083

研究了浸蚀对极化和未极化的BaTiO3单晶中畴变和压痕裂纹扩展的影响.结果表明,对面内极化试样(即极化方向 [001],压痕面(100)),用HCl+HF水溶液浸蚀20 s,其压痕裂纹的平均长度由(140±+17)μm扩展至(211±26)μm,即增长 50％,同时压痕裂... 详细信息

研究了浸蚀对极化和未极化的BaTiO3单晶中畴变和压痕裂纹扩展的影响.结果表明,对面内极化试样(即极化方向 [001],压痕面(100)),用HCl+HF水溶液浸蚀20 s,其压痕裂纹的平均长度由(140±+17)μm扩展至(211±26)μm,即增长 50％,同时压痕裂纹所围的90°畴变区也明显增大;先浸蚀再打压痕和压痕后再浸蚀所得的结果相同.其原因和浸蚀刺分子吸附降低表面能有关.对离面极化试样(即压痕面(001)垂直于极化方向[001]),则浸蚀对其裂纹长度和畴变区基本没有影响.对未极化试样,浸蚀使其裂纹长度从(150±21)μm增至(182±30)μm,即增长约20％,同时畴变区亦增大.

关键词： BaTiO3单晶浸蚀畴变压痕裂纹

BaTiO_3单晶压痕裂纹的畴变和裂纹扩展的原位观察

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金属学报 2006年第12期42卷 1274-1278页

作者：王瑞敏褚武扬宿彦京高克玮乔利杰石家庄铁道学院材料科学与工程分院石家庄050043 北京科技大学材料物理与化学系北京100083

金相显微镜原位观察了面内极化的BaTiO3单晶在瞬时电场作用下的畴变和裂纹形核、扩展的关系以及未极化BaTiO3单晶在恒电场下Vickers压痕裂纹扩展和电致畴变的关系．结果表明,畴变是裂纹形核、扩展的先决条件,但不存在直接的关系．在恒... 详细信息

金相显微镜原位观察了面内极化的BaTiO3单晶在瞬时电场作用下的畴变和裂纹形核、扩展的关系以及未极化BaTiO3单晶在恒电场下Vickers压痕裂纹扩展和电致畴变的关系．结果表明,畴变是裂纹形核、扩展的先决条件,但不存在直接的关系．在恒电场下,未极化的BaTiO3单晶卸载压痕裂纹的滞后扩展可以导致畴变区的扩大．

关键词： BaTiO3单晶瞬时电场恒电场 90°畴变裂纹扩展

Three-dimensional molecular dynamics simulation of hydrogen-enhanced dislocation emission and crack propagation

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Progress in Natural Science:Materials International 2002年第9期 79-82页

作者： LI Zhongji, chu Wuyang, LI Jinxu, gao kewei and QIAO Lijie(Department of Materials Physics, University of Science and Technology Beijing, Beijing 100083, China) Department of Materials Physics University of Science and Technology Beijing Beijing 100083 China

A three-dimensional molecular dynamics simulation using the embedded atom method (EAM) potentials shows that for both pure Ni and Ni+ H, dislocations are firstly emitted during loading and the crack propagates after enough dislocations are emitted. In the case of hydrogen embrittlement, local plastic deformation is a precondition for crack propagation. For the crack along the (111) slip plane, one atom fraction in percent of hydrogen can decrease the critical stress intensity for dislocation emission KIe from 0. 42 to 0. 36 MPam1/2, and that for crack propagation KIp from 0. 80 to 0:76 MPam1/2. Therefore, hydrogen enhances dislocation emission and crack propagation.

关键词： molecular dynamics simulation hydrogen dislocation emission crack propagation nickel.