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SOLIDIFICATION MICROSTRUCTURE AND fracture morphology OF SiCp/ZA27 COMPOSITE

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Chinese Journal of Mechanical Engineering 2001年第1期14卷 86-90页

作者： Zhao Yutao Zhou Ming Department of Materials,Jiangsu University of Science and TechnologySun Guoxiong Southeast University 江苏理工大学材料学院江苏镇江东南大学江苏

Solidification microstructure and mechanical property are ***,tensile fracture and microstructure are analyzed by using SEM and JXA 840A electron *** results indicate that SiC particles in SiCp/ZA27 composite are mainly distributed on interfaces or between dendrites and surrounded by primary α *** dendrite of α phase is fined by *** tensile strength at room temperature decreases with the increasing of SiCp *** tensile strength at elevated temperature increases with the addition of *** fracture of SiCp/ZA27 composites is the mixture of tough and brittle *** carck is prone to extend along the interface and the region of dispersed shrinkage.

关键词： SiCp/ZA27 composite Solidification microstructure fracture morphology

Effects of laser heat treatment on the fracture morphologies of X80 pipeline steel welded joints by stress corrosion

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International Journal of Minerals,Metallurgy and Materials 2014年第9期21卷 898-905页

作者： De-jun Kong Cun-dong Ye College of Mechanical Engineering Changzhou University

The surfaces of X80 pipeline steel welded joints were processed with a CO2 laser, and the effects of laser heat treatment （LHT） on H2S stress corrosion in the National Association of Corrosion Engineers （NACE） solution were analyzed by a slow strain rate test. The fracture morphologies and chemical components of corrosive products before and after LHT were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively, and the mechanism of LHT on stress corrosion cracking was discussed. Results showed that the fracture for welded joints was brittle in its original state, while it was transformed to a ductile fracture after LHT. The tendencies of hydrogen-induced corrosion were reduced, and the stress corrosion sensitivity index decreased from 35.2% to 25.3%, indicating that the stress corrosion resistance of X80 pipeline steel welded joints has been improved by LHT.

关键词： pipeline steel welded joints laser heating stress corrosion fracture morphology

Microstructure and fracture toughness of the Bridgman directionally solidified Fe-Al-Ta eutectic at different solidification rates

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Journal of Materials Science & Technology 2020年第7期42卷 63-74页

作者： Chunjuan Cui Cong Wang Pei Wang Wei Liu Yuanyuan Lai Li Deng Haijun Su School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Shaanxi Engineering Technology Research Center for Wear-resisting Materials Xi’an 710055China

Fe-Al-Ta eutectic composites were obtained by a modified Bridgman directional solidification technique at different solidification *** microstructure transforms from regular eutectic to eutectic colony with the increase of the solidification *** solid/liquid interface of Fe-Al-Ta eutectic evolves from planar interface to cellular interface with the increase of the solidification *** addition,threepoint bending method was adopted to study the room-temperature fracture toughness of the as-cast Fe-Al-Ta eutectic alloy and the Fe-Al-Ta eutectic ***,the fracture morphologies,the crack propagation path and the strengthening mechanism of Fe-Al-Ta eutectic were discussed.

关键词： Directional solidification Eutectic composite Solid/liquid interface fracture toughness fracture morphology

fracture Morphologies of Advanced High Strength Steel During Deformation

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 101-106页

作者： Ying Sun Xifeng Li Xiangyu Yu Delong Ge Jun Chen Jieshi Chen Department of Plasticity Technology.School of Materials Science and Engineering Shanghai Jiao Tong University

The fracture morphologies of several advanced high-strength steels （DP590, DP780, DP980, Ml180, and M1300） formed in uniaxial tension and piercing were observed by scanning electron microscope, and then quantitatively analyzed by image processing technique. The tension-induced fractographs are dominated by obvious uniform or bimodal size dimples, while shearing-induced fractographs have smooth surfaces and few dimples. The fracture zone of higher grade DP steels is smoother. As for M1180 and M1300, the fracture zones consist of very small dimples and smooth brittle surfaces. The dimple size of M1300（ ,- 1.2 tm） is smaller than that of M1180（ 1.6 tm）. Moreover, in the tensile fracture, the quantitative correlation between average dimple diameter （d） and tensile strength （a） can be represented by d = 10,502.32a-121. However, the relation between dimple density and tensile strength is not monotonic due to the appearance of bimodal size dimples with increase of tensile strength. For shearing-induced fracture during piercing, the fitted empirical model between the percentage of burnish zone （f） and tensile strength can be described asf --- 239.9a-＇36.

关键词： High strength steel fracture morphology Dimple size Burnish zone Tensile strength

fracture propagation and induced strain response during supercritical CO_(2)jet fracturing

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Petroleum Science 2022年第4期19卷 1682-1699页

作者： Can Cai Bang-Run Li Yi-Yao Zhang Wen He Ying-Xin Yang Yong Kang Ji-Wei Wu School of Mechanical Engineering Southwest Petroleum UniversityChengdu610500SichuanP.R.China The State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanP.R.China Shu'nan Gas-Mine of Southwest Oil and Gas Field Company Luzhou646000SichuanP.R.China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan UniversityWuhan430072HubeiP.R.China School of Engineering and Applied Sciences and Department of Physics Harvard UniversityCambridge02138United States School of Mechanical Engineering Yangtze UniversityJingzhou434023HubeiP.R.China

To investigate fracture generation and strain variation during SC-CO_(2)(supercritical carbon dioxide)jet fracturing,the model of induced strain is established and the experiments are comprehensively *** influence factors are comprehensively explored,such as jet pressure,ambient pressure,*** the increasing jet pressure,the fracture morphology changes from parallel cracks to oblique *** the mass loss of specimen and CO_(2) absorption increase significantly,and the growth rate and minimum value of strain also rise *** a high ambient pressure of 8.0 MPa,the main fractures mostly propagated from the surface to the bottom surface of the *** maximum strain and the stable duration under higher ambient pressure are 1.5 times and 10 times,respectively,of the case under the ambient pressure of 5.0 *** comparison shows that the optimal jet distance is 5-7 times the nozzle diameter,resulting in massive mass loss,large CO_(2)absorption,and peak ***,the nonlinear variation of strain curve during jet pressurization is related to the type of rock and ambient *** studies clearly show the relationship between the fracture morphology and induced strain,which are crucial for SC-CO_(2)fracturing in shale gas reservoirs.

关键词： Supercritical carbon dioxide fracturing Jet fracturing fracture morphology Strain variation

Synthesis and compressive fracture behavior of a CuZr-based bulk amorphous alloy with Ti addition

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Journal of Central South University 2013年第5期20卷 1137-1141页

作者：陈鼎董建峰马国芝 College of Materials Science and Engineering Hunan University

Cu46Zr46A14.8Ti3.2 bulk metallic glass （BMG） was successfully synthesized by copper-mold casting and the mechanical properties at room temperature were measured by compression tests. The structure and thermal characteristics were analyzed by XRD and DSC, and the fracture surface morphology was examined by SEM. The glassy alloy with 4 mm in diameter shows an high fracture strength of 1 960 MPa, with an improvement of about 20% compared to the ultimate compression fracture strength of the Cu46Zr46A18 BMG, which suggests that the Ti addition improves the compression fracture strength. The different degrees of the adiabatic heating induce four types of fracture features： a vein-like structure, an elongated and striated vein pattern, melting and smooth regions. The elongated and striated vein patterns as well as the melting region show that enormous strain energy is released, which causes significant adiabatic heating. Furthernaore, many micro-cracks observed in the smooth region are caused by the strong shear force. In addition, the strong shear force leads to many shear bands as well as the melting in the lateral surface.

关键词： Cu-Zr-Ti-A1 bulk metallic glass compression fracture behavior fracture morphology adiabatic heating

Low temperature impact toughness and fracture mechanism of cast QT400-18L ductile iron with diferent Ni additions

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China Foundry 2013年第5期10卷 310-314页

作者： Zhang Xinning Qu Yingdong Yang Hongwang Li Rongde School of Materials Science and Engineering Shenyang University of Technology

Different contents of Ni(0.3wt.%to 1.2wt.%)were added to the QT400-18L ductile iron to investigate the effect of Ni addition on the impact toughness of cast ductile irons at low *** impact toughnesses of the samples at room and low temperatures were *** microstructures and fractographs were *** show that with the increase of Ni addition there is a general trend of refinement of the ferrite matrix while the nodule density shows no obvious *** the Ni content is 0.7wt.%,the matrix structure is the refined ferrite with a very small fraction(about 2%)of pearlite near the eutectic cell *** the Ni content is further increased,the fraction of pearlite increases significantly and reaches more than 5%when 1.2wt.%Ni is *** impact toughness at room temperature increases as the content of Ni increases from 0.3 wt.%to 0.7 wt.%,but decreases as the Ni content further increases to 1.2wt.%due to the increase of pearlite *** maximum value of the impact work is 18.5 J at room temperature with 0.7wt.%Ni *** average value of the impact work is still more than 13 J even at-30℃.In addition,the fracture mechanism changes from ductile manner to brittleness as the testing temperature decreases from 20℃to-60℃.

关键词： Ni ductile iron low temperature impact toughness fracture morphology

fracture properties of epoxy asphalt mixture based on extended finite element method

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Journal of Central South University 2012年第11期19卷 3335-3341页

作者：钱振东胡靖 Intelligent Transportation System Research Center Southeast University

Crack is found to be a major distress that affects the performance of the epoxy asphalt *** extended finite element method was proposed for investigating the fracture properties of the epoxy asphalt ***,the single-edge notched beam test was used to analyze the temperature effect and calculate the material ***,the mechanical responses were studied using numerical *** is concluded that 5℃ can be selected as the critical temperature that affects the fracture properties,and numerical simulations indicate that crack propagation is found to significantly affect the stress state of the epoxy asphalt *** maximum principal stress at the crack surface exhibits different trends at various *** solution of stress intensity factor can well meet the theoretical solution,especially when the temperature is lower than 5℃.

关键词： epoxy asphalt mixture microstructure extended finite element method fracture morphology mechanical response

EFFECT OF RARE EARTH ADDITIONS ON fracture PROPERTIES OF 2.25Cr-1Mo STEELS

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Acta Metallurgica Sinica(English Letters) 1989年第1期2卷 63-68页

作者： W.R.TYSON B.FAUCHER Physical Metallurgy Research Laboratories CANMETOttawaCanada

The inclusion parameters,fracture surface morphology and void growth characteristics of ten- sile and fracture toughness specimens of 2.25Cr-1Mo steels with and without rare-earth (RE)additions have been investigated by quantitative metaltography(QTM),scanning elec- tron microscopy(SEM)and energy dispersive spectroscopy(EDS).There is a substantially higher density of inclusions in the RE-treated steel,which has lower values of fracture proper- ties including critical values of COD and J integral(δ_c and J_(IC)),fracture strain(ε_f) and Charpy V-notch energy(CVN).The fracture surface of the RE-treated steel comprises equiaxed dimples of diameters comparable with its inclusion spacing,whereas for the non-RE-treated steels,a wide range of dimple sizes is found with average diameter much smaller than the corresponding inclusion *** investigation indicates that the lower values of fracture properties for the steel with RE at room temperature may be ascribed to its large content of RE-containing inclusions.

关键词： Cr-Mo steel fracture properties inclusion parameters fracture morphology