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| 1 | Experimental and numerical study of failure behavior and mechanism of coal under dynamic compressive loads显示文摘A comprehensive understanding of the failure behavior and mechanism of coal is a prerequisite for dealing with dynamic problems in mining space.In this study,the failure behavior and mechanism of coal under uniaxial dynamic compressive loads were experimentally and numerically investigated.The experiments were conducted using a split Hopkinson pressure bar(SHPB)system.The results indicated that the typical failure of coal is lateral and axial at lower loading rates and totally smashed at higher loading rates.The further fractography analysis of lateral and axial fracture fragments indicated that the coal failure under dynamic compressive load is caused by tensile brittle fracture.In addition,the typical failure modes of coal under dynamic load were numerically reproduced.The numerical results indicated that the axial fracture is caused directly by the incident compressive stress wave and the lateral fracture is caused by the tensile stress wave reflected from the interface between coal specimen and transmitted bar.Potential application was further conducted to interpret dynamic problems in underground coal mine and it manifested that the lateral and axial fractures of coal constitute the parallel cracks in the coal mass under roof fall and blasting in mining space. | Junjun Feng Enyuan Wang Qisong Huang Houcheng Ding Xiangyang Zhang | 2020 | International Journal of Mining Science and Technology2020，30，5： | 13 |
| 2 | Microstructure and mechanical properties of Al/Cu/Mg laminated composite sheets produced by the ARB proces显示文摘In the present study, an Al/Cu/Mg multi-layered composite was produced by accumulative roll bonding(ARB) through seven passes, and its microstructure and mechanical properties were evaluated. The microstructure investigations show that plastic instability occurred in both the copper and magnesium reinforcements in the primary sandwich. In addition, a composite with a perfectly uniform distribution of copper and magnesium reinforcing layers was produced during the last pass. By increasing the number of ARB cycles, the microhardness of the layers including aluminum, copper, and magnesium was significantly increased. The ultimate tensile strength of the sandwich was enhanced continually and reached a maximum value of 355.5 MPa. This strength value was about 3.2, 2, and 2.1 times higher than the initial strength values for the aluminum, copper, and magnesium sheets, respectively. Investigation of tensile fracture surfaces during the ARB process indicated that the fracture mechanism changed to shear ductile at the seventh pass. | Davood Rahmatabadi Moslem Tayyebi Ramin Hashemi Ghader Faraji | 2018 | International Journal of Minerals,Metallurgy and Materials2018，25，5： | 10 |
| 3 | Evaluation of physical and mechanical properties of AZ91D/SiC composites by two step stir casting process显示文摘Magnesium alloy(AZ91D)composites reinforced with silicon carbide particle with different volume percentage were fabricated by two step stir casting process.The effect of changes in particle size and volume fraction of SiC particles on physical and mechanical properties of composites were evaluated under as cast and heat treated(T6)conditions.The experimental results were compared with the standard theoretical models.The results reveal that the mechanical properties of composites increased with increasing SiC particles and decrease with increasing particle size.Distribution of particles and fractured surface were studied through SEM and the presence of elements is revealed by EDS study. | S.Aravindan P.V.Rao K.Ponappa | 2015 | Journal of Magnesium and Alloys2015，3，1： | 5 |
| 4 | Creep rupture behavior and microstructural evolution of modified 9Cr-1Mo heat-resistant steel显示文摘High-temperature creep rupture behavior of modified 9Cr-lMo steel used for steam cooler was investigated at temperature of 838 and 923 K and stress ranging from 100 to 250 MPa.Based on the analysis of creep rate-time curves,it is found that the creep rupture life decreases with the increase in the applied stress and temperature.The creep damage tolerance factor has been identified as a value of 8.In the normalized and tempered condition,the studied steel shows typical martensitic microstructure with Cr-rich M23C6 and Nb-or V-rich MX precipitates.Moreover,the Laves phase has been found along the grain boundaries.The fracture morphology characterized by field emission scanning electron microscope is adopted to reveal the creep failure mechanisms.The investigated results indicate the occurrence of the transgranular fracture under all the creep test conditions. | Fa-cai Ren He Wang Xiao-ying Tang Fei Chen | 2018 | Journal of Iron and Steel Research(International)2018，25，12： | 3 |
| 5 | Effect of welding heat input on microstructure and impact toughness in CGHAZ of X100Q steel显示文摘The coarse-grained heat-affected zones (CGHAZs) of X100Q steel were reproduced via simulating their welding thermal cycles with the varying heat input (Ef) from 10 to 55 kJ/cm in Gleeble3500 system. The microstructures were characterized, and the impact toughness was estimated from each simulated sample. The results indicate that the microstructure in each simulated CGHAZ was primarily constituted of lath-like bainite. With the decreased heat input and accordingly the lowered Ar3 (the onset temperature for this transition), the prior austenite grain and the bainitic packet/block/lath substructure were refined remarkably, and the impact toughness was enhanced due to the microstructure refinement. The bainitic packet was the microstructural unit most effectively controlling the impact properties in CGHAZ of X100Q steel, due to their close correlation with the 50% fracture appearance transition temperatures, their size equivalent to the cleavage facet and their boundaries impeding the crack propagation. | Hui-bin Wang Fei-long Wang Gen-hao Shi Yu Sun Jiang-cheng Liu Qing-feng Wang Fu-cheng Zhang | 2019 | Journal of Iron and Steel Research(International)2019，26，6： | 3 |
| 6 | Microstructure and mechanical properties of two-stage aged Al-Cu-Mg-Ag-Sm alloy显示文摘High-strength Al-Cu-Mg-Ag-Sm alloy was fabricated and subjected to single-stage aging and pre-aging(two-stage aging). Effect of pre-aging on micros tructure and mechanical properties of the alloy was investigated. It is found that the alloy is mainly composed of α-Al, Al_2Cu, Al_2CuMg and AlCu_4Sm. The number of plate-like Ω Al_2Cu precipitates is comparable to that of rod-like S Al_2 CuMg precipitates in the single-stage aged alloy, whereas, in the two-stage aged alloy, it is much higher than that of S precipitates. Q precipitates have a smaller plate thickness and distribute more uniformly in the two-stage aged alloy than in the single-stage aged alloy.Ultimate tensile strength(UTS) and yield strength of the two-stage aged alloy are 12% higher than those of the single-stage aged one, indicating a better aging hardening caused by the two-stage aging. The increased tensile properties mainly come from both stronger precipitation strengthening caused by more Ω precipitates in the twostage aged alloy and stronger solution strengthening from Mg atoms. The fracture surfaces consist of both dimple zones composed of microscale dimples and platform zones composed of nanoscale dimples. The total area of dimple zones for single-stage aged alloy is much higher than that for two-stage aged alloy, which can be attributed to different numbers of Ω precipitates in the two alloys. | Wen-Long Zhang Dai-Hong Xiao Ting Li Jian-Di Du Dong-Yan Ding | 2019 | Rare Metals2019，38，1： | 2 |
| 7 | Fractographic analysis of the overload effect on fatigue crack growth in 2024-T3 and 7075-T6 Al alloys显示文摘The effect of single overload on the fatigue crack growth in 2024-T3 and 7075-T6 Al alloys was analyzed.Fatigue tests under constantamplitude loading with overload peak were carried out on V-notched specimens.Fractographic analysis was used as a principal approach to explain the crack growth retardation due to the overload.Scanning electron microscopy(SEM)analyses were conducted on the fractured surface of failed specimens to study the retardation effect.The obtained results show that the overload application generates a plastic zone in both aluminum alloys.The generated plastic zone is three times larger in the case of 2024-T3 compared to 7075-T6,and thus,a significant crack retardation was induced for 2024-T3.The retardation effect due to the overload for 2024-T3 and 7075-T6 lasted for about 10 mm and 1 mm,respectively,from the point of overload application. | A.Albedah B.Bachir Bouiadjra S.M.A.K.Mohammed F.Benyahia | 2020 | International Journal of Minerals,Metallurgy and Materials2020，27，1： | 2 |
| 8 | Repair Effect of Hot Work Tool Steel by Laser-Melting Process显示文摘Both wear and crack due to heat checking in hot work tool steel are major failure modes. It is desirable to find amethod to lengthen the tool life while reducing manufacturing cost. This paper suggests a method to improve toollife for hot work tool steel (SKD6) with crack by laser-melting process. The method has been evaluated using theimpact and fatigue test results. It is demonstrated that a repair of the crack by a laser-melting process is effectivefor life extension of the damaged tool. | Yahong SUN Satoshi HANAKI Hitoshi UCHIDA Hisakichi SUNADA Nobuhiro TSUJII | 2003 | Journal of Materials Science & Technology2003，19，z1： | 2 |
| 9 | Erosive wear properties of ZA-27 alloy-based nanocomposites: Influence of type, amount, and size of nanoparticle reinforcements显示文摘Metal matrix nanocomposites(MMnCs)comprise a metal matrix filled with nanosized reinforcements with physical and mechanical properties that are very different from those of the matrix.In ZA-27 alloy-based nanocomposites,the metal matrix provides ductility and toughness,while usually used ceramic reinforcements give high strength and hardness.Tested ZA-27 alloy-based nanocomposites,reinforced with different types(Si C and Al2O3),amounts(0.2 wt.%,0.3 wt.%,and 0.5 wt.%)and sizes(25 nm,50 nm,and 100 nm)of nanoparticles were produced through the compocasting process with mechanical alloying pre-processing(ball milling).It was previously shown that the presence of nanoparticles in ZA-27 alloy-based nanocomposites led to the formation of a finer structure in the nanocomposites matrix and an improvement in the basic mechanical properties(hardness and compressive yield strength)through the enhanced dislocation density strengthening mechanism.Solid particle erosive wear testing demonstrated that these improvements were followed with an increase in the erosive wear resistance of tested nanocomposites,as well.Additionally,by analyzing the influences of type,amount,and size of nanoparticles on the erosive wear resistance of nanocomposites,it was demonstrated that there is an optimal amount of nanoparticles,which in our case is 0.3 wt.%,and that the presence of SiC nanoparticles and smaller nanoparticles in nanocomposites had more beneficial influence on erosive wear resistance. | Aleksandar VENCL Ilija BOBIC Biljana BOBIC Kristina JAKIMOVSKA Petr SVOBODA Mara KANDEVA | 2019 | Friction2019，7，4： | 1 |
| 10 | Effects of mechanical vibration on the physical,metallurgical and mechanical properties of cast A308(LM21)aluminum alloy显示文摘This study investigated the microstructure,physical,and mechanical properties of die-cast A308 alloy subjected to mechanical vibration during solidification.Different frequencies(0,20,30,40,and 50 Hz)at constant amplitude(31μm)were employed using a power amplifier as the power input device.X-ray diffraction,optical microscopy,and scanning electron microscopy were used to examine the morphological changes in the cast samples under stationary and vibratory conditions.Metallurgical features of the castings were evaluated using Image J software.The average values of metallurgical features,including primaryα-Al grain size,dendrite arm spacing,average area of eutectic silicon,aspect ratio,and percentage porosity,reduced by 34%,59%,56%,22%,and 62%,respectively,at 30 Hz frequency compared with stationary casting.Mechanical tests of the cast samples showed that the yield strength(YS),ultimate tensile strength(UTS),percentage elongation(%EL),and microhardness(HV)increased by 8%,13%,17%,and 16%,respectively,at 30 Hz frequency compared with stationary casting.The fractured surface of the tensile specimens exhibited mixed-mode fracture behavior because of brittle facets,cleavage facets,ductile tearing,and dimple morphologies.The presence of small dimples showed that plastic deformation occurred before fracture. | Siddharth Yadav S.P.Tewari J.K.Singh S.C.Ram | 2022 | International Journal of Minerals,Metallurgy and Materials2022，29，6： | 1 |
| 11 | 超声波Fractography在测试裂纹尖端动态剪切模量中的应用显示文摘介绍用超声波Fractography技术测量高速扩展裂纹尖端准微观区域内材料的剪切模量的实验原理和方法.本方法目前尚限于在脆性高分子材料中应用,在其它材料中的应用以及实验方法本身都期待着进一步完善和发展. | 盛季生 | 1992 | 纺织基础科学学报1992，5，3： | 0 |
| 12 | Understanding stress corrosion cracking behavior of 7085-T7651 aluminum alloy in polluted atmosphere显示文摘The electrochemical and Stress Corrosion Cracking(SCC)behaviors of 7085-T7651 aluminum alloy in different environments are studied by electrochemical and mechanical testing.The research shows that the type,concentration of the corrosive medium and electrolyte state affect the electrochemical and SCC controlling processes of aluminum alloys.The Thin Electrolyte Layer(TEL)state and the addition of HSO3–increase the corrosion rate and SCC susceptibility.The presence of HSO3–in a corrosive environment can significantly accelerate the corrosion rate and mechanical property degradation,and this effect increases with the increase of HSO3–concentration.Compared with the solution environment,the TEL environment will further aggravate corrosion and mechanical property degradation.With the increase of HSO3–concentration,the pH of the corrosive environment exhibits little change,while the SCC degradation is significantly promoted.This is attributed to the HSO3–induced buffer effect and film-assisted stress effect,yielding the overshadowing effect against solution pH. | Mingtao WANG Liwei WANG Kun PANG Yuxi LIU Yuxue WANG Zhongyu CUI | 2023 | Chinese Journal of Aeronautics2023，36，8： | 0 |
| 13 | Low-cycle fatigue behaviour of Mg-9Gd-4Y-2Zn-0.5Zr alloys with different structures显示文摘The strain-controlled cyclic deformation behaviour of Mg-9Gd-4Y-2Zn-0.5Zr with different structures was investigated. Alloys were prepared by solution, extrusion and pre-ageing extrusion, and the microstructures before and after the fatigue tests were characterized.Experimental results indicated that the bimodal structure owned the better performance in fatigue test, which was attributed to the higher yield strength. For the equiaxed structure, cyclic hardening induced stress concentration until the failure. Stable cyclic deformation and persistent cyclic softening played an important role at the low and high strain amplitudes, respectively. This was attributed to the formation of fine grains relieving the stress concentration during cyclic loading. In addition, residual twins were observed in equiaxed structure to induce crack, and the bimodal structure effectively restrain it. | Jinsheng Ji Jie Zheng Leichen Jia Yong Zhang Yunfei Jia Yusha Shi Heng Zhang Yong Xue | 2023 | Journal of Magnesium and Alloys2023，11，9： | 0 |
| 14 | Retrieving Effective Stress Spectrum of Fatigued Components from Fractographic Quantitative Analysis显示文摘Under the constant amplitude and pro-grammed loading conditions the fatigued fracturesurfaces of 2024-T3 sheet are examined by SEMand TEM.A corrected method,in which the effectsof loading sequence are taken into account,hasbeen developed for the retrieval of effective stressspectrum.The parameters including d,a,C,n,R,αand σ_y are evaluated according to their influenceson the retrieved results.Several computer programshave been produced for the fractographic quantita-tive analysis,and the application of image pro-cessing technique in the fractographic analysis is al-so interpreted. | 武淮生 钟群鹏 | 1992 | Journal of Materials Science & Technology1992，8，1： | 0 |
| 15 | MICROFRACTOGRAPHY OF NEAR-THRESHOLD FATIGUE CRACK GROWTH显示文摘The fracture surface micromorphology in the near-threshold FCG region was studied inLD-10 aluminum alloy and Ti-6Al-4V allov.The SEM examinations reveal that the frac-ture surface of both alloys at low crack growth rates(1×10-7-1×10-5mm/cycle)takes ona cyclic facet appearance.The typical morphologies were either sawtoothedfacets or terracedfacets for LD-10 aluminum alloy and isolated island facets for Ti-6Al-4V alloy.The mech-anism of near-threshold fatigue crack growth is explicated on the basis of experimental ob-servations. | YANG Jingjun KE Wei Institute of Corrosion and Protection of Metals,Academia Sinica,Shenyang,China YANG Jingjun Institute of Corrosion and Protection of Metals,Academia Sinica,Wencui Road,Shenyang,China | 1990 | Acta Metallurgica Sinica(English Letters)1990，3，1： | 0 |
| 16 | Effects of Zr additions on structure and tensile properties of an Al-4.5Cu-0.3Mg-0.05Ti(wt.%) alloy显示文摘The effects of different Zr additions(0.05wt.%-0.5wt.%)on the structure and tensile properties of an Al-4.5Cu-0.3Mg-0.05Ti(wt.%)alloy solidified under a high cooling rate(18℃·s^(-1)),in as-cast and T6 heat-treated conditions were studied.The as-cast structure of the alloy consists of equiaxed grains ofα-Al with an average size of 64μm which is unaffected by the Zr additions,indicating the ineffectiveness of Zr in the grain refinement of the alloy.Scanning electron microscopy,along with X-ray diffraction analysis revealed the presence of elongatedθ-Al2Cu at the grain boundaries;in addition,coarse Al3Zr particles exist in the intergranular regions of the 0.5wt.%Zr-containing alloy.After the T6 heat treatment,the elongatedθparticles were fragmented;however,the coarse Al3Zr particles remained unchanged in the microstructure.Also,the formation of fineβ’-Al3Zr andθ’’-Al3Cu/θ’-Al2Cu phases during T6 heat treatment was revealed by transmission electron microscopy.The results of the tensile tests showed that the Zr additions increase the strength of the alloy in both as-cast and T6 heat-treated conditions,but reduce its elongation,especially with 0.5wt.%Zr addition.The 0.3wt.%Zr-added alloy in the T6 heat-treated condition has the highest quality index value(249 MPa).Fractography of the fracture surfaces of the alloys revealed ductile fracture mode including dimples and cracked intermetallic phases in both conditions. | Hamed Kamali Erfan Kamali Massoud Emamy | 2022 | China Foundry2022，19，1： | 0 |
| 17 | Assessment of self-reacting bobbin tool friction stir welding for joining AZ31 magnesium alloy at inert gas environment显示文摘Research work presented in this study has the primary target of exploring joint attributes of AZ31 magnesium alloys using friction stir welding process with a modified tool referred as bobbin tool.Effects of inert and open atmosphere on mechanical properties are evaluated over a wide range of welding speed and tool rotation speed.Comparison of the research findings from the inert atmosphere bobbin tool were made with the traditional process of friction stir welding.The results depicted improved joint properties for inert atmosphere welding.Low and intermediate range of tool rotational speed is found to be favorable for bobbin tool friction stir welding without and with an inert medium,respectively.Controlled atmosphere due to inert medium leads to less oxidation of the AZ31 Mg alloy leading to superior joint properties.Microstructural investigations are also made with the aim of evaluating the impact of bobbin tool and inert medium on joint properties.In each aspect for joining of AZ31 Mg alloy,bobbin tool with inert medium is found to be an effective solution for joining with improved mechanical properties compared to without inert bobbin tool as well as conventional tool friction stir welding. | Prakash Kumar Sahu Nikhil P Vasudevan Bipul Das Sukhomay Pal | 2019 | Journal of Magnesium and Alloys2019，7，4： | 0 |
| 18 | STUDY ON FRACTOGRAPHY OF TRANSGRANULAR SCC OF 70Cu-3OZn IN AN AMMONIACAL SOLUTION显示文摘The microfractography of transgranular stress corrosion cracking (TSCC) of 70Cu-30Zn a-brass in ammoniacal solution was studied. The observations indicate that on a very microscale, the crack path of TSCC of or-brass follows {111} planes. The crack path very often alternates between {111} Planes to result in 'cleavage-like'facet, the usual average orientation of which is {110} with preferential microscopic crack propagation in (100) and (112) directions. The average orientation of wide secondary facets is often close to {100}. The size of {111} microfacets increases with incrmsing stress intensity K, which indicates that the microscopic crack path follows {111} planes on which some localized slip has occurred. Possible TSCC mechanisms which appear to be consistent with the microfraphic features observed in the present study are also discussed. | S.Q.Li J.I.Dickson J.P.Bailon | 1998 | Acta Metallurgica Sinica(English Letters)1998，11，5： | 0 |
| 19 | Fractography and morphology of shear bands of a Zr-based bulk metallic glass显示文摘Bulk metallic glasses(BMGs)have attracted considerable attention in the last few decades particularly triggered by their potential applications as novel structural and/or functional materials,owing to their superior strength,large elastic strain limit and relatively low Young′s modulus etc.compared to their crystalline counterparts.Here,a 3Dreconstruction application to the fractography and the morphology of shear bands was reported for a ductile Zr_(56)Co_(28)Al_(16)(at.%)BMG through a Phenom series desktop scanning electron microscope.The results of the 3Dreconstruction and the following contour analysis indicate a typical shear fracture mode for the investigated alloy.It is inferred that the fractography and the morphology of shear bands might be dependent on their composition,structure states,and loading conditions for BMGs. | Jun Tan Jun-yan Gao Xue-mei Qin Zheng-rong Fu Dong Li Min Li Xiu-chang Wang Gang Wang | 2017 | Journal of Iron and Steel Research(International)2017，24，4： | 0 |
| 20 | Non-Linearity of the Mirror Constant for Glasses Fractured in Flexure显示文摘Fractography relies on topographic features on the fracture surfaces to deduce the stress state of the failed component. Traditionally, fractographers assumed that the fracture strength of brittle materials was related to the reciprocal of the square root of the mirror radius linearly, in accordance with the empirical equation formally postulated by Orr in 1972. In this manuscript a novel analytical model to describe the dynamic behavior of elliptical cracks was derived on the basis of thermodynamic principles. Unlike Orr's equation, the proposed model considered the effects of the plate thickness and it could be used to improve the strength prediction based on the plate's geometry and material properties. To verify the validity of the model, 39 annealed, 2 mm thick,soda-lime silicate glass plates were fractured by four-points bending test and the fracture surfaces were imaged by confocal laser microscope and carefully studied. Excellent agreement was observed between the experimental data and the proposed theoretical framework. | 马凌越 DUGNANI Roberto MOULINS Anthony | 2018 | Journal of Shanghai Jiaotong university(Science)2018，23，1： | 0 |
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