• Table of Content
      20 April 2011, Volume 0 Issue 4 Previous Issue    Next Issue
    For Selected: View Abstracts Hide(Show) Pic
    Effect of Heat Processing on Microstructure and Mechanical Property of Inconel718 Superalloy Multi-sheet Coreboard Structures
    QU Feng-sheng, LU Zhen, ZHANG Kai-feng, LI Bao-yong
    2011, 0 (4): 1-8.  
    Abstract ( 392 ( PDF (3608KB)( 341 Citation
    The Inconel718 superalloy with multi-sheet coreboard structure was manufactured by LBW+SPF complex technology.In order to enhance the security of multi-sheet coreboard structure,the heat treatment processing was studied.The results show that Laves precipitation phase which contains higher content Nb element in the welding process of Inconel718 superalloy.After SPF process,Nb segregation in the weld is partly dissolved.The heat treatment of solution treatment at 980℃/30min can make δ phase dissolve thoroughly into the γ phase and the Nb content of the dendritic in the weld joint steps up.The heat treatment of solution treatment at 1080℃/30min can make Laves phase dissolve and solve the problem of segregation Nb.Grain size of Inconel718 superalloy by solution treatment 1080℃ grows up greatly.The yield strength compared after superplastic forming decreases slightly.
    References | Related Articles | Metrics
    Optimized Design of Composite Skin-stiffened Structure with Large Cutout
    LUO Chu-yang, XIONG Jun-jiang, YI Xiao-su, ZHANG Zi-long, LIU Gang
    2011, 0 (4): 9-13.  
    Abstract ( 408 ( PDF (1599KB)( 222 Citation
    The optimized design of composite skin-stiffened structure with large cutout was conducted by finite element method.The effect of cutout reinforcement and stiffened reinforcement to the buckling load was investigated.The results show that stress concentration is far away from the free edge of hole after flanged reinforcement.The buckling load enhances with increasing both flanged depth and width.The co-cure stiffened is better than integral stiffened.At coordinative condition,the low and dense stiffener is recommended,as well as increasing transverse stiffeners.
    References | Related Articles | Metrics
    Study on High Temperature Corrosion of Water Wall Materials in Simulated Furnace Atmosphere
    ZHANG Zhi-xiang, CHENG Ding-nan, BIAN Bao, JIN Yong-qiang, XU Liang-hong, ZHAO Qin-xin
    2011, 0 (4): 14-19.  
    Abstract ( 391 ( PDF (1750KB)( 165 Citation
    Candidate materials of supercritical and ultra-supercritical utility boiler water wall T91 and 12Cr1MoV were chosen as the experimental samples,and exposed to an oxidizing atmosphere,a reducing atmosphere and an oxidizing/reducing alternating atmosphere respectively.The corrosion temperature was 450℃.The corroded samples were analyzed by scanning electron microscope and energy dispersive spectrometer.To describe the corrosion of the materials accurately,the mass gain,the macro-thickness,and the migration depth were simultaneously analyzed.The combination corrosion of oxygen and sulfur had a stronger corrodibility than that of pure H2S.Cr2O3 had little effect in resisting H2S corrosion,but it can hinder the combination corrosion model.T91 had a stronger corrosion resistance than 12Cr1MoV.
    References | Related Articles | Metrics
    Simulation Study on Coarse Grain Heat Affected Zone of High Strength Oil Tank Steel
    XIA Dian-xiu, SHANG Cheng-jia, HOU Dong-hua, SUN Hao, LI Xing-fang
    2011, 0 (4): 20-24.  
    Abstract ( 344 ( PDF (1456KB)( 195 Citation
    The effects of welding thermal cycle on the microstructure and mechanical properties of Coarse Grain Heat Affected Zone(CGHAZ) of high strength oil tank steel which was treated under series high weld heat input were studied by using welding thermal simulation.The results show that the test steel has good ability to resist thermal shock of 80-100kJ/cm welding heat input.With the increasing of welding heat input,the microstructure of CGHAZ gradually becomes more coarse and the toughness gradually decreases.There are many fine and dispersed second-phase particle of TiN in test steel.It is important factor to make the steel to resist thermal shock of high welding heat input for which can prevent growth of primary austenite and promote phase transformation of ferrite as nucleus.
    References | Related Articles | Metrics
    Analyses on Microstructure of Hypoeutectic Alloy with Different Cooling Rate
    ZHANG Pei-lei, YAO Shun, YU Zhi-shui, DING Min, XU Pei-quan
    2011, 0 (4): 25-28.  
    Abstract ( 458 ( PDF (958KB)( 206 Citation
    The XRD analysis was carried out with the melted filler metal.The copper was brazed with the BCuP-5 filler metal.The microstructure and phase constitution of brazing seam were studied by scanning electron microscope(SEM) and energy dispersive X-ray detector(EDX).The forming mechanism of brazing seam was discussed.The results showed that the structure in the brazing seam was consisted of hypoeutectic alloy.The primary phase is copper solid solution containing a small amount of silver and phosphorus.The eutectic phase was copper solid solution,silver solid solution and Cu3P.The morphology of brazing seam was concerned with cooling rate.In the lower cooling rate,the microstructure morphology of brazing seam was hypoeutectic with uniform layered,dispersedly distributed.In the higher cooling rate,the microstructure morphology of brazing seam was nonuniform hypoeutetic.
    References | Related Articles | Metrics
    Dynamics Research on Non-isothermal Oxidation Reaction of AlN Powder
    WANG Rong-lin, SUN Jia-lin, BU Jing-long, WANG Zhi-fa
    2011, 0 (4): 29-32,37.  
    Abstract ( 417 ( PDF (531KB)( 185 Citation
    The process and dynamics parameters of non-isothermal oxidation of AlN powder(d50=5μm) were studied by TG-DTA and XRD in atmosphere of 4/5N2 and 1/5O2 mixture with flow rate of 55mL/min and heating rate of 10℃/min.The results showed that the AlN powder obviously began to be oxidated and its mass increased over 900℃.The process of dynamics of oxidation reaction between AlN and O2 was controlled alternately by reaction and diffusion.Non-isothermal oxidation dynamics parameters(activation energy E,reaction orders n and pre-exponential factor A) of the AlN powder were obtained by the experimental data.E equals about 417.4kJ/mol,n about 2.9 and A about 3.47×1012h-1.Due to smaller activation energy E and larger pre-exponential factor A in dynamics parameters of AlN powder non-isothermal oxidation,AlN powder is easily oxidated with larger oxidation reaction rate at high temperature and air.Actual measurement thermogravimetric curve is in agreement with theoretical calculation.It shows that the dynamics equation based on these dynamics parameters data of non-isothermal oxidation of d50=5μm AlN powder is reasonable.
    References | Related Articles | Metrics
    Investigation of Microstructure and Performance of C/W Multilayer Coatings with W Interlayer
    CHEN Di-chun, JIANG Bai-ling, SHI Hui-ying, FU Yang-hong
    2011, 0 (4): 33-37.  
    Abstract ( 409 ( PDF (1714KB)( 266 Citation
    C/W multilayer coatings with W interlayer were deposited on steel substrates using unbalanced magnetron sputtering.The surface morphology,phase composition and cross-section microstructure were analyzed by SEM,XRD and TEM method.The tribological property and adhesion of film to substrate were tested.The results show that the coating is a composite coating composed of amorphous carbon and nanocrystalline WC,which has a clear multilayer structure with a periodical thickness of 6.5nm.The friction coefficient decreases with the increasing in substrate bias,the coatings deposited at-90V bias have the lowest friction coefficient,the value is 0.14.Thickness of W interlayer is 500nm,the use of W interlayer does not enhance the adhesion of film to substrate due to the generation of high compressive stresses in W interlayer.
    References | Related Articles | Metrics
    Experimental Investigation on Dynamic Compression Properties of UHMWPE/Vinyl Ester 2.5 Dimensional Angle Interlocked Woven Composites
    SUN Ying, WANG Guo-jun, ZHANG Dian-tang, CHEN Li, ZHANG Ming
    2011, 0 (4): 38-42.  
    Abstract ( 381 ( PDF (1300KB)( 215 Citation
    The compressive properties of composites in the through-thickness direction were tested using the SHPB and SHIMADZU.The compressive stress-strain curve,and strain at yield stress,and impact energy absorption of the composites were obtained under three kinds of high strain rates(360,710s-1 and 1120s-1) and quasi-static compression,which had the same fiber volume fraction.The compressive failure mode and energy absorption mechanism were discussed from the breakage configurations of coupons.The results indicated that the compressive properties of UHMWPE/vinyl ester 2.5D angle interlocked woven composites in the through-thickness direction were strain rate dependent.The yield stress,strain at yield stress and modulus were sensitive to the strain rates,and all increased with the increased of strain rate.Additionally,the damage started from the bending area of the warp and downs to shear fracture along the through-thickness direction.The separation between fiber tow and resin and the shear fracture of fiber tow were the predominant failure modes of the composites under dynamic compressive loading,energy absorption for elastic property of component materials and shear fracture of the fiber tow were the major energy absorption mechanisms.
    References | Related Articles | Metrics
    Effect of Sulphate Reducing Bacteria on Corrosion of Al-Zn-In-Mg-Ti Anode in Marine Sediment
    ZHANG Jie, LIU Feng-ling, LI Wei-hua, DUAN Ji-zhou, ZHAI Shen-bao, HOU Bao-rong
    2011, 0 (4): 43-48.  
    Abstract ( 449 ( PDF (1635KB)( 221 Citation
    A comparative study about the corrosion behavior of Al-Zn-In-Mg-Ti sacrificial anode in marine sediment without and with sulphate reducing bacteria(SRB) was carried out using electrochemical impedance spectroscopy(EIS),scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS).The electrochemical studies showed that the corrosion potential for samples exposed to sterile marine sediment was higher than that for samples exposed to the SRB-containing marine sediment during the whole experiment;the corrosion of the sample was enhanced sharply in the presence of SRB.SEM images revealed that the presence of localized corrosion morphologies on the surface of sample immersed in the sterile medium as well as in the biotic medium,but the damage in the biotic medium was more severe than that in the sterile medium.EDS analysis showed that the concentration of Al and Zn in the surface film for the sample with SRB was much lower than that for the sample without SRB.
    References | Related Articles | Metrics
    Study of Bending Behavior of 304 Stainless Steel Coating by Cold Gas Dynamic Spraying
    HAN Wei, MENG Xian-ming, ZHAO Jie, ZHANG Jun-bao
    2011, 0 (4): 49-53.  
    Abstract ( 427 ( PDF (1237KB)( 215 Citation
    304 stainless steel coating was deposited on the IF steel substrate by cold gas dynamic spraying(CGDS).The three-point bend test of the cold sprayed 304 stainless steel coating was tested by SHIMADZU electro-hydraulic servo-controlled fatigue testing machine and the fracture behavior of the cold sprayed 304 stainless steel coating was examined by scanning electron microscopy.The results showed that the fracture behavior of the cold sprayed 304 stainless steel coating was brittleness fracture.The first crack initiation was happened in the coating’s surface,then the crack extended to the internal of the coating with the increased of the load and the shape of the crack in the coating was V-shaped;when the crack got to the combination interface of coating and substrate,the crack extend to the two sides along the interface;interface cracking and coating spalling were observed in the combination interface of coating and substrate when the adjacent crack interconnected.
    References | Related Articles | Metrics
    Study on Influence of Calculating Length on Evaluation Result of Stress by Surface Acoustic Wave for Coating
    LIU Bin, DONG Shi-yun, XU Bin-shi, HE Peng
    2011, 0 (4): 54-57,70.  
    Abstract ( 397 ( PDF (1189KB)( 202 Citation
    Based on the theory of acoustoelastic effect,using mechanical tensile experiment,the residual stress of coating was evaluated by the method of surface acoustic wave.The difference in time of flight among the ultrasonic signals caused by difference tensile stress is calculated on the base of cross-correlation function.The results show that when the tensile stress is less than elastic limit of coating,the velocity of surface acoustic wave is bigger and bigger with tensile stress increasing in coating,and when the tensile stress is bigger than a certain value,microcrack appears and expands gradually with the tensile stress increasing in coating,so the velocity of surface acoustic wave also changes correspondingly.The length of reference signal(n) is a vital factor for calculating result of cross-correlation function.The tendency of tensile stress and difference in time of flight is prone to linear increasing with value of n increasing.And when the value of n attains one cycle,the calculating result between tensile stress and difference in time of flight is basic similar with tensile stress increasing.By calculating the evaluation parameter of linear fitting result,the result of fitting value of cross-correlation function and root-square error also show that when the length of reference signal is one cycle,the calculating result of cross-correlation function is optimal for the evaluation of tensile stress.
    References | Related Articles | Metrics
    Effects of Grain Size on Resistance and Transmittance Transition of Vanadium Oxide Thin Film
    LIANG Ji-ran, HU Ming, KAN Qiang, CHEN Tao, LIANG Xiu-qin, CHEN Hong-da
    2011, 0 (4): 58-62,74.  
    Abstract ( 459 ( PDF (1585KB)( 332 Citation
    Vanadium oxide thin films were deposited by reactive direct current facing targets magnetron sputtering,and then annealed in oxygen ambience under different temperature to fabricate phase transition vanadium dioxide thin films with different grain size.The transformation of resistance and transmittance of vanadium oxide thin films were measured across phase transition.The results show that the proportion of VO2 in film is about 40%(atom fraction) after annealed in 300℃ and 360℃,the films have insulator-metal phase transition properties.The grain size is 50nm and 100nm,respectively.After annealing at 360℃,the surface of vanadium oxide thin film becomes compact and some grain comes to merge.Electrical and optical transition properties across phase transition show that the transition temperature decreases as grain size increasing,however,the temperature width of phase transition keep constant.The temperature width of phase transition obtained from electrical transition properties is about 30℃,but that from optical transition properties is only 8℃.
    References | Related Articles | Metrics
    Failure Analysis on Fabroil of Buffer Axile Bush
    FAN Jin-juan, LI Ying, JIANG Tao, TAO Chun-hu
    2011, 0 (4): 63-65,83.  
    Abstract ( 542 ( PDF (694KB)( 208 Citation
    The buffer axile bush of an undercarriage cracked and fractured during service.The failure cause of the fabroil of the buffer axile bush was investigated by appearance inspection,fracture surface observation,properties testing and analyzing the built-up structure and force of the fabroil.The results show that the cracks of the fabroil are fatigue cracks and the fracture of the fabroil is a result of fatigue cracking.The main cause of fatigue cracks is that there is a gap caused by transition fit between the fabroil and the copper bush.After the oil enters into the gap,the tensile stress on the fabroil is far higher than the designed oil pressure and linearly relates to the oil pressure.The oil pressure exceeds the resistance of the fabroil and the fabroil cracks.
    References | Related Articles | Metrics
    Effect of Martensite on Yield Characteristics of Cold Rolled C-Si-Mn Dual Phase Steel
    ZHU Guo-ming, KUANG Shuang, CHEN Gui-jiang, CHEN Bo, REN Jun-ru
    2011, 0 (4): 66-70.  
    Abstract ( 440 ( PDF (1350KB)( 268 Citation
    Based on the annealing and tempering in lab,the effect of martensite volume fraction(MVF) and tempering temperature on yield characteristics of trial dual phase(DP) steel were investigated by mechanical test and microstructure analysis.The results show that the MVF increases from 0% to about 15%,the yield stress of DP steels decreases significantly,the decrease values are between 80MPa and 100MPa;When MVF is in 15%-35%,the yield stress of DP steels maintains at a lower level,whereas,when MVF is more than 35%,the yield stress increases rapidly.When MVF exceeds 10%,the DP steels represent continuous yield.With the increasing of tempering temperature from 200℃ to 400℃,the yield stress of DP steels increases monotonously,and the yield platform reappears when tempering temperature is more than 300℃.Based on the observation and analysis to the fine microstructures of DP steels,the high density phase transformation induced dislocation and residual stress are considered as the potential reasons for the low stress and continuous yield of DP steels.
    References | Related Articles | Metrics
    Effect of Zn to Solute Segregation and Structure During Solidification of Mg-6Al Alloy
    WU Yu, PAN Fu-sheng, JIANG Bin, XIAO Lu
    2011, 0 (4): 71-74.  
    Abstract ( 459 ( PDF (1055KB)( 344 Citation
    The solid-liquid interfaces of Mg-6Al and Mg-6Al-0.5Zn alloys were obtained by rapid quenching,the solute segregation characteristic of Al in the two alloys was analyzed.The results showed that the near equilibrium distribution coefficient,the segregation rate and the most segregation ratio for Al in Mg-6Al alloys were 0.33,2.17 and 0.43,respectively.However,when Zn was added into Mg-6Al alloys,the near equilibrium distribution coefficient,the segregation rate and the most segregation ratio for Al in Mg-6Al alloys increased.The morphology of primary α-Mg phase changed from celliform dendrite to equiaxed dendrite,and the solidification structure was refined in a way.
    References | Related Articles | Metrics
    Effect of Temperature Gradient on Primary Dendrite Spacing During Directional Solidification of Al-4.5%Cu Alloy
    SI Nai-chao, XU Neng-jun, SI Song-hai, LI Yun-da, SHI Jian
    2011, 0 (4): 75-79.  
    Abstract ( 382 ( PDF (1350KB)( 464 Citation
    The drop-down 5kg crucible directional solidification equipment was used and the directional solidification experiment of Al-4.5%Cu alloy was carried out.The primary dendrite spacing of Al-4.5%Cu alloy under the conditions of different temperature gradient was studied.The results show that with the increasing of the temperature gradient,the primary dendrite spacing becomes smaller,meticulous and upright in other solidification parameters remaining unchanged.The basic shape is parallel to the distribution,meanwhile,the computed value of the primary dendrite arm spacing is closed to value with the Hunt calculated.The test measures the value of primary dendrite arm spacing in a regressive curve:y=2843478.3x2-70217.4x>+543.8.With a higher temperature gradient to simulate the experimental values,the availability of λ>1=26.7G-0.5-135.9 is got.The primary dendrite arm spacing λ1 almost is linear with G-0.5.This is consistent with Hunt analyzed result.
    References | Related Articles | Metrics
    Study on Tribological Characteristics of Fe-Al/Cr3C2 Composite Coating at Different Temperatures
    LIU Xiao-ming, DONG Jun-hui, XU Run-sheng
    2011, 0 (4): 80-83.  
    Abstract ( 391 ( PDF (832KB)( 346 Citation
    Using THT07-135 high temperature machinery to analysis tribological properties of high velocity flame spraying(HVFS) Fe-Al/Cr3C2 composite coating,wear scar images and composites in different region were analyzed by SEM and EDS,existing state of reinforcement were analyzed by TEM.The results show that coating has relatively better friction and wear resistance properties,friction coefficient changes little with the increasing of wear distance.Wear resistance performance of coating differs from normal metallic materials.With increasing in temperature,it increases firstly and reaches a peak at 550℃,then decreases later.Hamper effect of reinforcements in coating makes the wear resistance performance of coating better.The predominant wear mechanism of the Fe-Al/Cr3C2 coatings is exfoliation.The mainly reason why the high-temperature wear resistance properties of Fe-Al/Cr3C2 composite coating differs from normal metallic materials is the yield strength of basic phase Fe-Al intermetallics in coating changing with high-temperature is unusually.
    References | Related Articles | Metrics
    Study of Corrosion Resistance and Anti-corrosion Mechanism of Rare Earth Conversion Coatings on Zinc Plating in 5%NaCl Solution
    ZHANG Jiang-hong, ZHANG Ying-jie
    2011, 0 (4): 84-88,93.  
    Abstract ( 322 ( PDF (1538KB)( 190 Citation
    The morphology,structure and phase of rare earth conversion coating were characterized by SEM,XPS and XRD.The corrosion resistance of rare earth conversion coating,zinc coating and low-chromium conversion coating were compared by immersion experiments,the neutral salt spray tests and electro-chemical testing methods.The corrosion kinetic parameters of rare earth conversion coating were measured in 5%NaCl solution.The results showed that rare earth conversion coating was formed by tiny fine particles without cracks and less defects,which was composed of zinc and cerium oxides and hydroxides,hindered O2 transmission and electronic transmission,inhibited both reactions of anodic and cathodic of corrosions,decreased corrosion kinetics and protected matrix from corrosion effectively.It improved the corrosion resistance performance of zinc plating,whose corrosion resistance was better than that of low-chromium conversion coating.
    References | Related Articles | Metrics
    Microstructure and Abrasion Resistance of Hypereutectic High-boron Hardfacing Alloys
    GONG Jian-xun, XIAO Yi-feng, MA Mo
    2011, 0 (4): 89-93.  
    Abstract ( 327 ( PDF (1296KB)( 218 Citation
    Hypereutectic high-boron hardfacing alloys containing 0.1-1.0 C,4-13 Cr,2.5-3.2 V,2.2-3.8 B(mass fraction/%) were deposited by using submerged arc welding(SAW) flux-cored wire.The microstructure and boride morphology were investigated by optical microscopy(OM),scanning electron microscopy(SEM) and X-ray diffraction(XRD).The microstructure consists of ferrite,martensite,residual austenite,borides and carbide such as M2B,M32C,etc.The volume fraction of primary boride M2B varied with boron content.In addition,the effects of carbon content on hardness and wear properties of high-boron hardfacing alloys were evaluated.The results showed that the hardness value was up to HRC 66.5 and the abrasion resistance was excellent.With the increased of carbon concentration,both the hardness and abrasion resistance firstly enhanced,and then decreased.The wear mechanism changed from abrasive particle micro-cutting to micro-area spalling together with micro-cutting.
    References | Related Articles | Metrics
    Application of Continuous Electric Field in Metal Solidification
    HUANG Li-guo, FU Da-jun, GAO Zhi-yu
    2011, 0 (4): 94-97.  
    Abstract ( 310 ( PDF (193KB)( 217 Citation
    The effect of DC electric field and AC electric field on solidified structure of alloys,solute redistribution and super-cooling was analyzed.With the theory of electricity and metal solidification,the major mechanism of continuous electric field in metal solidification was summarized and concluded.And its mechanics to refine the dendrite arm spacing of alloys were theoretically discussed,a reference to application of continuous electric field in the practical production was offered.
    References | Related Articles | Metrics