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Cyclic Creep Deformation and fracture of a Cr-Mo Rotor Steel at Elevated Temperatures

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Journal of Materials Science & Technology 1992年第4期8卷 255-260页

作者：朱世杰阳志安王中光 State Key lab.ratory for fatigue and fracture of Materials Institute of Metal ResearchAcademia SinicaShenyang110015China

Static creep and cyclic creep tests were carried out on a Cr-Mo rotor steel from 0.5 to 0.6 T_m. Cyclic creep retardation occurred under the test *** an increase of stress frequency, cyclic creep strain rate decreases and rupture time *** cyclic creep strain rate for the stress wave of a square shape is higher than that of a tri- angle *** apparent stress exponent of cyclic creep and the apparent activation energy of cyclic creep are both higher than those of static *** minimum strain rate is inversely proportional to rupture time for both static and cyclic creeps at dif- ferent stresses,temperatures,frequencies and wave *** cyclic creep retardation mechanism was explored by the observation and analysis of the dis- location structure and fracture surface.

关键词： fracture cyclic creep retardation Cr-Mo steel

fatigue Behaviour of Metal Matrix Composites

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Journal of Materials Science & Technology 1992年第4期8卷 235-248页

作者：王中光孙正明于维成 State Key lab.ratory for fatigue and fracture of Materials Institute of Metal ResearchAcademia SinicaShenyang.110015China

Based mainly on the work done at the authors' lab.ratory in recent years,this paper examines what is currently known about the cyclic deformation and fatigue properties of metal matrix composites, with particular emphasis on discontinuous fiber (whisker or particulate)-reinforced Al composites. The following items are discussed:fatigue strength and life,cyclic deformation and microstructural evolution,microcrack initiation and growth,fatigue crack propagation behaviour.

关键词： metal matrix composite cyclic deformation and fatigue interfacial effect crack-trapping and bridging

Investigation in Crack Growth of A537 Steel and Its Weld Metal in Artificial Sea Water

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Journal of Materials Science & Technology 1989年第4期5卷 254-258页

作者：臧启山刘慷柯伟朱自勇 lab.ratory of fatigue and fracture of Sinica MaterialsIMRChina Institute of Corrosion and Protection of Metals Academia SinicaShenyangChina

The crack growth rates of A537 c1.1 steel and its weld metal have been investigated both in air and in artificial sea *** effects of stress ratio,frequency,residual stress of welds as well as corrosion products on cor- rosion fatigue crack growth rate have been exa- *** electrochemical reactions occurred during tests and models for describing the cor- rosion fatigue crack growth process in low strength of offshore structural steel were discussed.

关键词： crack growth stress ratio effect corrosion fatigue

Dislocation Behaviour near the Crack Tip in Bulk Fe-3% Si Single Crystal

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Journal of Materials Science & Technology 1991年第1期7卷 35-39页

作者：徐永波哈宽富王中光杨春松戴忠玲 lab.ratory for fatigue and fracture of Materials Institute of Metal ResearchAcademia Sinica.To whom correspondence should be addressed. Jilin University Changchun130023China. lab.ratory for fatigue and fracture of Materials Institute of Metal ResearchAcademia SinicaShenyang110015China.

An investigation has been made of the disloca- tion distribution and dislocation free zone near the crack tip in bulk Fe-3% Si single crystal during deformation in *** has been found that a number of dislocations were emitted from the crack tip during *** that,the dislocations moved rapidly away from the crack tip,which indi- cated that they were strongly repelled by the stress field at the crack *** the crack tip and the plastic zone there is a region of dislocation-free, which is referred to as dislocation-free zone (DFZ). The length of DFZs is roughly estimated 100 μm which is much longer than that found in thin foil *** variation of dislocation density as a function of the distance from the crack tip was measured,which showed that the dislocations are inversely piled up in the plastic *** length of DFZs increased with both the length of pre-crack and the amplitude of applied stress.

关键词： dislocation crack tip DFZ Fe-3%Si single crystal

Predictive fatigue crack growth law of high-strength steels

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Journal of Materials Science & Technology 2022年第5期100卷 46-50页

作者： H.F.Li P.Zhang B.Wang Z.F.Zhang lab.ratory of fatigue and fracture for Materials Shi-changxu Innovation Center for Advanced MaterialsChinese Academy of SciencesInstitute of Metal ResearchShenyang 110016China State Key lab.ratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

The fatigue resistance of metallic materials is generally attributed to both strength and ***,these properties are mutually exclusive in most *** theories like Paris’law only provide some data correlation schemes rather than a predictive capability,which cannot satisfactorily guide the anti-fatigue *** this study,for the first time,the predictive fatigue crack growth rate law is proposed by considering the effects of both strength and ***,a quantitative criterion is established for judging the fatigue crack resistance of high-strength *** predictive law would provide a unique view to the quantitative anti-fatigue design of metallic materials.

关键词： fatigue crack growth Strength and toughness Paris’law High-strength steels

Effect of Build Direction on fatigue Performance of L-PBF 316L Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2020年第4期33卷 539-550页

作者： Chenfan Yu Yuan Zhong Peng Zhang Zhenjun Zhang Congcong Zhao Zhefeng Zhang Zhijian Shen Wei Liu State Key lab.ratory of New Ceramic and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Department of Materials and Environmental Chemistry Arrhenius LaboratoryStockholm University10691 StockholmSweden lab.ratory of fatigue and fracture for Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The microstructure and fatigue and tensile properties of 316 L stainless steel fabricated via laser powder bed fusion(L-PBF)were *** 316 L stainless steel specimens with different loading directions which are either perpendicular to or parallel to building direction were prepared by L-PBF *** results of X-ray diffraction tomography showed that there was no significant difference in morphology and size/distribution of the defects in the HB and VB *** long axis of columnar grains is generally parallel to the build direction,the fatigue crack encounters more grain boundaries in VB samples under cyclic loading,which led to enhanced fatigue resistance of VB samples compared with HB *** contrast to HB sample,the VB sample has a higher fatigue strength due to a higher resistance to localized plastic deformation under cyclic *** differences in fatigue properties of L-PBF 316 L SS with different build directions were predominantly controlled by solidification microstructures.

关键词： Austenitic stainless steel Laser powder bed fusion Tensile properties fatigue strength

Self-accommodated defect structures modifying the growth of Laves phase

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Journal of Materials Science & Technology 2021年第3期62卷 203-213页

作者： Tong Yang Yi Kong Jiangbo Lu Zhenjun Zhang Mingjun Yang Ning Yan Kai Li Yong Du State Key lab.ratory of Powder Metallurgy Central South UniversityChangsha410083China School of Physics and Information Technology Shaanxi Normal UniversityXi’an710119China Materials fatigue and fracture Division Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Institute for Materials Microstructure Central South UniversityChangsha410083China

Laves phases,with the topologically close-packed structure and a chemical formula of Ab_(2),constitute the largest single class of *** defects in Laves phases are widely investigated,especially for stacking behavior transformations through ***,we report the coexistence of C14,C36 and C15 structures in MgZn_2 precipitates by using atomic resolution scanning transmission electron microscopy,verifying the previously predicted Laves phase transformation sequence of C14→C36→C15 also applies to MgZn_*** type of stacking fault couple in precipitates has been found to alone reduce the lattice mismatch with matrix,while some other stacking fault couples need to self-accommodate with irregular planar defects(rhombic units and flattened hexagonal units),or with five-fold symmetry structures to relieve the strain *** thus grow towards an equiaxed or even round morphology,rather than the plate morphology as conventionally *** dynamics calculations are performed to support our *** findings reveal the principles governing the concurrent occurrence of various defects in laves structures,acting as an update of the widely accepted perception of random occurrence of defects during crystal growth.

关键词： High angle annular dark field(HAADF) Defects Stacking faults Strain

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高频载荷下高强钢的超高周疲劳及热耗散研究

材料工程 2009年第3期37卷 49-53页

作者：薛红前杨斌堂 C.Bathias 西北工业大学机电工程学院西安710072 ITMA/CNAM Laboratory of Fatigue and Fracture Mechanics

应用超声疲劳试验技术,对两种高强度钢(42CrMo4,100Cr6)在20kHz频率下的超高周疲劳性能进行测试分析。实验结果表明:两种钢的S-N曲线在106周发生了明显的变化,出现了水平渐近线。尽管23个42CrMo4钢试样用于1010周的疲劳试验,但在8.76×... 详细信息

应用超声疲劳试验技术,对两种高强度钢(42CrMo4,100Cr6)在20kHz频率下的超高周疲劳性能进行测试分析。实验结果表明:两种钢的S-N曲线在106周发生了明显的变化,出现了水平渐近线。尽管23个42CrMo4钢试样用于1010周的疲劳试验,但在8.76×107循环周次以上,没有疲劳破坏发生,42CrMo4钢存在疲劳极限,而100Cr6钢的S-N曲线呈现台阶型。高精度热成像仪检测不同载荷条件下疲劳试样温度的变化结果显示:温度的变化与试验材料和加载水平有关。试样温度的快速升高发生在超声疲劳试验的初期,温度的变化反映了材料内部的热耗散过程。裂纹萌生后,微裂纹处不可逆的局部塑性变形导致裂纹萌生区温度急剧升高,疲劳试样内部温度场的变化反映材料的疲劳损伤过程。SEM观察表明:在长寿命区,疲劳裂纹常萌生于试样内部或次表层组织缺陷处。

关键词：超声疲劳高强度钢超高周疲劳 42CrMo4 100Cr6 热耗散

XFEM modeling of hydraulic fracture in porous rocks with natural fractures

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Science China(Physics,Mechanics & Astronomy) 2017年第8期60卷 45-59页

作者： Tao Wang ZhanLi Liu QingLei Zeng Yue Gao Zhuo Zhuang Applied Mechanics lab. School of Aerospace Engineering Tsinghua University

Hydraulic fracture （HF） in porous rocks is a complex multi-physics coupling process which involves fluid flow, diffusion and solid deformation. In this paper, the extended finite element method （XFEM） coupling with Biot theory is developed to study the HF in permeable rocks with natural fractures （NFs）. In the recent XFEM based computational HF models, the fluid flow in fractures and interstitials of the porous media are mostly solved separately, which brings difficulties in dealing with complex fracture morphology. In our new model the fluid flow is solved in a unified framework by considering the fractures as a kind of special porous media and introducing Poiseuille-type flow inside them instead of Darcy-type flow. The most advantage is that it is very convenient to deal with fluid flow inside the complex frac^xre network, which is important in shale gas extraction. The weak formulation for the new coupled model is derived based on virtual work principle, which includes the XFEM formulation for multiple fractures and fractures intersection in porous media and finite element formulation for the unified fluid flow. Then the plane strain Kristianovic-Geertsma-de Klerk （KGD） model and the fluid flow inside the fracture network are simulated to validate the accuracy and applicability of this method. The numerical results show that large injection rate, low rock permeability and isotropic in-situ stresses tend to lead to a more uniform and productive fracture network.

关键词： hydraulic fracture XFEM porous media fluid flow multi-physics coupling