CHEN Bang-feng, JIA Pan-jiang. Fracture Surface and Chemical Composition of Segregation Defect of ZL205A Casting Aluminum Alloy[J]. Journal of Materials Engineering, 2010, 0(9): 1-6,24.
Segregation defect of Al-Cu alloy ZL205A casting during production was researched as an object.The effect of segregation defect on the mechanical properties of the casting and the macro/microstructure of the fracture surface,and the relationship of the mechanical properties and the segregation area were studied.The results show that segregation defect has obvious effect on the tensile strength and the elongation,and no effect on the yield strength.The average value of the elongation is 3.7% lower than that of I grade 4%,while the tensile strength and the yield strength is 391.3MPa and 343.5MPa more than that of I grade 360MPa and 280MPa,respectively.It is ductile fracture for defect-free samples,and while intercrystalline brittle fracture for the segregation defect samples.The segregation defect accumulates along the grain boundaries with the continuous networks,and its main composition is low-melting-point eutectic phase Al2Cu.There is a linear logarithmic relationship between the tensile strength and the segregation area of the samples.
YANG Xiao-hua, CHEN Wei-qing, HAO Zhan-quan. Effects of Ti Metamorphic Disposal on Solidification Structure of Fe-Ni Base Invar Expansion Alloy[J]. Journal of Materials Engineering, 2010, 0(9): 7-9,14.
Metamorphic disposal method and SEM graphic analysis were applied to evaluate the effect of Ti metamorphic disposal on solidification structure of Fe-Ni base invar expansion alloy.The results show that great amount of high-melting compounds(Ti2O3)with the size of 2μm are formed in the Fe-Ni base invar expansion alloy after Ti metamorphic disposal.The Ti2O3 acts as the heterogeneous nucleation,so the solidification structure of the alloy is refined from complete dendrite grain to most equiaxed grain.TiN,TiC,Ti(NC),Ti2O3 which take effect of preventing the growth of crystal grain are distributed in interface of equiaxed grain.
XIAO Lai-rong, ZHANG Lu-huai, LIU Yan, ZHANG Xi-min, HU Jia-rui. Microstructure and Property of Magnesium Brass[J]. Journal of Materials Engineering, 2010, 0(9): 10-14.
A new environmentally friendly cutting brass containing magnesium instead of lead was produced by casting and extruding.The microstructure of studied alloy was observed by scanning electron microscope(SEM)and optical microscope(OM)and the mechanical,thermal properties,dezincification and cutting properties were studied.The result shows that α-phase,β-phase and Cu2Mg phase exist in alloy.The tensile strength,yield strength,elongation and hardness of magnesium are 494.39,388.56MPa,8.78% and HV140.7 respectively.It is feasible to develop a new nonleaded free-cutting magnesium brass.
YANG Hai-qing, WANG Zhao-yong, XIAO Cheng-bo, TANG Ding-zhong. Microstructure and Mechanical Properties of Alloy GH22 as Insulate Plates Against Heat in Industrial Gas Turbine[J]. Journal of Materials Engineering, 2010, 0(9): 15-19.
The tensile properties at room and high temperatures were tested with equiaxed specimens of the alloy GH22 made by vacuum induction melting method.The insulate plates against heat used in industrial gas turbine were manufactured by investment casting.The macro grain and microstructure were analyzed by optical metallography(OM),scanning electron microscopy(SEM)and energy dispersive spectrum(EDS).The tensile and stress-rupture properties of specimens cut from domestic and foreign parts were also tested,respectively.The results show that the composition and tensile properties can meet the specification of insulate plates against heat of alloy GH22.The grain size and tensile properties both at room-temperature and high-temperature are comparable between domestic parts and foreign parts.The increment in high temperature stress rupture properties of domestic parts with higher carbon contents is induced by more carbides precipitated at the interdendrites and grain boundaries.
HE Pei, ZHOU Zhang-jian, LI Ming, XU Ying-li, GE Chang-chun. Effect of Starting Materials and Milling Atmosphere on Mechanical Alloying of ODS Ferritic Steels[J]. Journal of Materials Engineering, 2010, 0(9): 20-24.
Microstructural features of two oxide dispersion strengthened(ODS)ferritic steels by mechanical alloying using pure metal powders and nitrogen atomized powder as raw materials respectively were investigated.Microstructure analysis by SEM and X-ray diffraction,laser diffraction/scattering particle size distribution analyzer,and chemical analysis were used to compare the mechanical alloying effects between these two starting materials.The results show that the alloying elements distribute more homogeneous employing the nitrogen atomized powder as raw materials than that of using pure metal powders.Furthermore,mechanical alloying under high purified Ar atmosphere can better reduce the excess oxygen content than that of under vacuum mechanical alloying.
WU Kai-ming. Technical Comparison on Production of Electrical Steels with Different Continuous Casting Process[J]. Journal of Materials Engineering, 2010, 0(9): 25-28,32.
For the production of electrical steels with thin slab,medium thin slab and conventional continuous casting process,technical comparisons were made on their technological aspects such as slab cast microstructures,distribution and size of precipitates,slab surface quality,which can provide technical considerations in choosing production route and slab quality control for electrical steels.
FENG Li-ming, WEI Xue. Preparation and Structure of Sn-Cu Alloys by Electrochemical Deposition[J]. Journal of Materials Engineering, 2010, 0(9): 29-32.
The anode material Sn-Cu alloy for lithium battery was deposited onto a copper foil by electrodeposition.The effects of bath composition on the Cu content of plating were investigated by energy dispersive spectroscopy(EDS)and the structure of coatings with different Cu contents was studied before and after heat treatment by X-ray diffractometer(XRD).Experimental results show that the concentration of Cu2P2O7 and K4P2O7 has significant effects on the Cu contents of platings.When the both concentrations are changed,the Cu contents range from 20.18%(mass fraction)to 58.05%.The as-deposited alloy platings are composed of Cu,Sn and η-Cu6Sn5 when the contents of copper are 20.18%,31.01% and 58.05% respectively.When the deposits are heated at more than 300℃ for 1h,structure of the platings is transformed.The Cu contents of the precipitated electronic compounds increase comparing with those of the as-deposited platings.As copper content of the plating is 20.18% or 58.05%,the structure of alloy platings is almost unchanged with the temperature increasing.However,the Cu contents of new phases decrease when heat treatment temperature rises from 300℃ to 500℃ for the film consisting of 31.01% Cu.
YU Kun, CAI Zhi-yong, WANG Xiao-yan, SHI Ti, LI Wen-xian. Simulation of Multi-pass Hot Rolling Process of Direct-chilled AZ31B Magnesium Alloy[J]. Journal of Materials Engineering, 2010, 0(9): 33-39.
Based on practically press-working technology,the eleven-pass continuous hot rolling process of direct-chilled AZ31B magnesium alloy with the distributions of stress field,strain field and temperature field was simulated using rigid-plastic thermal-mechanic finite element method(FEM)with a DEFORMTM software.The results show that the stress,strain and temperature distribute inhomogenously along the thickness direction of the ingot during the hot rolling process.Great strain value is obtained as a result of high stress at the surface where the AZ31B alloy ingot contacts with the mill roller.But the stress and strain are relatively low at the centre of the alloy ingot.During a single hot rolling within the continuous process,stress obtains a maximum value when the ingot first touches the mill roller.The stress changes slightly during the rolling process but will decrease at the end of rolling.The equivalent stress distributes homogeneously after hot rolling 9 passes,and increases gradually with the increasing of pass.Comparisons show that experimental data get a good match with numerical simulation results during multi-pass hot rolling of AZ31B alloy.The flow stress of multi-pass increases gradually and reaches a steady-state subsequently at low strain rates(0.01,0.1s-1).But work hardening is obviously at the first three pass at high strain rates(5,10s-1),and then evidently softening occurs between the passes.
JIN Guang-can, ZHAO Ai-min, ZHAO Zheng-zhi, TANG Di, LIU Li, ZHOU Jian. Microstructure and Property of 800MPa Cold Rolled Hot Dip Galvanized Dual Phase Steel and Its Texture Evolution[J]. Journal of Materials Engineering, 2010, 0(9): 40-44.
Microstructures of hot rolled,cold rolled and hot dip galvanized annealed samples were observed,mechanical properties of hot rolled and hot dip galvanized annealed samples were analyzed and compared.At the same time,process of texture evolution was studied.The results show that annealed at 820℃ and soaked 140s,the tensile strength and total elongation of hot dip galvanized dual phase steel reach 819MPa and 17% respectively with F+M microstructure.The size of ferrite crystal grain is 1.5-4μm,the volume fraction of martensite is about 34%.The density of hot rolled texture is week,but γ-fiber texture is formed weekly;after cold rolling,α-fiber and γ-fiber texture both develop remarkably;after hot dip galvanized annealing,α-fiber texture changes very little,but {001}<110> texture increases notably.The orientation density of γ-fiber texture greatly fluctuates,the texture component {112} <110> possesses of maximum amount.The martensite particle which is formed in the process of rapid cooling hinders the development of favorable texture {111},so it makes that the disadvantage texture {001} <110> has a great extent increasing.
XU Fei, YANG Jing, GONG Shui-li, CHEN Li, LI Xiao-yan. Effects of Welding Parameters on Laser Welding of Aluminum Alloys with Filler Wire[J]. Journal of Materials Engineering, 2010, 0(9): 45-48.
Two types of material,including 5A06 aluminum alloy with 1.2mm thickness and 5A90 aluminum-lithium alloy with 3mm thickness,were joined by laser welding with ER5356 filler wire.The effects of welding parameters(the distance between the laser and the filler wire,weld feed speed,laser power and welding speed)on welding appearance were researched.The results show that the good welding appearance can be obtained when the distance between the laser and the filler wire is controlled within a range,and the range is affected obviously by the welding speed.Meanwhile,the higher wire feed speed and greater wire feed speed range tend to appear when the thinner aluminum alloy sheet is welded.The effect of welding speed on welding appearance is larger than that of laser power.As the welding speed increases,the laser power increases in order to realize the two welding parameters match each other.Besides,during laser welding with filler wire on the condition of good welding appearance and complete-penetration,the welding input should be kept as lower as possible.
CAO Wei-chan, LIANG Shu-hua, MA De-qiang, WANG Xian-hui, YANG Xiao-hong. Influence of Al2O3 Addition on Motion of Cathode Spot for CuW70 Alloy[J]. Journal of Materials Engineering, 2010, 0(9): 49-53,57.
CuW70 alloys with different additions of Al2O3 were prepared by infiltrating method.The effects of Al2O3 addition on microstructure and vacuum breakdown were investigated,and the motion of cathode spots of CuW70 alloys was observed utilizing high speed photography.The results show that the cathode spots of CuW70 alloys without Al2O3 addition are concentrated on the copper phases.The generation and extinguishment of cathode spots cause the serious erosion around the original site on the surface.For the CuW70 alloys with Al2O3 addition,the cathode spots are more dispersed,the first breakdown phase shift from copper to Al2O3 phase,and the erosion area decreases significantly.So,the arc-resistant life of CuW70 alloys is prolonged and the chopping current decreases with Al2O3 addition.
ZHANG Ding-fei, DAI Qing-wei, ZHANG Jun-ping, FANG Lin, HU Yao-bo, WANG Xiao-hong, LAN Wei. Effects of Initial Widths on Microstructures and Properties of Rolled AZ31 Sheets[J]. Journal of Materials Engineering, 2010, 0(9): 54-57.
AZ31 magnesium sheets with different initial widths were rolled under the same conditions.Hardness test,XRD and SEM experiments were used to investigate the effects of initial widths on microstructures and properties of rolled AZ31 magnesium sheets.The results show that the initial width has some effects on the rolled AZ31 magnesium alloy sheet.With the initial width increasing,the hardness at the edge of the rolled sheet becomes higher,more recrystallized grains are generated,and(0002)basal plane orientation XRD peaks are enhanced.At the central part of the rolled sheet,dynamic recrystallization occurs more completely,the hardness in the center is lower than that at the edge,(0002)basal plane orientation increases dramatically.
HU Jian-ping, CAI Ji-zhe, ZHAO Yan, LIU Jian-hua. Hygrothermal Resistance Properties of Nomex/Cyanate Ester Sandwich Composites[J]. Journal of Materials Engineering, 2010, 0(9): 58-61.
After conditioning in certain hygrothermal environment,70℃,85%RH,the mechanical and dielectric properties of Nomex/cyanate ester resin sandwich composite were investigated in the dry and wet conditions.The results show that the Nomex/cyanate ester sandwich composites have very good hygrothermal resistance properties.The conservation rate of dielectric properties of Nomex/cyanate ester sandwich composites is much higher than that of other kinds of materials,indicating its best hygrothermal resistance properties in dielectric properties.Comparing with the Nomex/epoxy sandwich composites,the Nomex/cyanate sandwich composite has better mechanical properties hygrothermal resistance performance,for its facing material of cyanate ester resin,which would bring better protection for its core structure.
WANG Yang-wei, MA Zhuang, YU Xiao-dong, WANG Fu-chi, HU Xin. Dynamic Indentation Hardness of Typical Materials[J]. Journal of Materials Engineering, 2010, 0(9): 62-65,70.
A dynamic indentation hardness measuring system was established successfully by loading a single compressive pulse on the diamond Vickers indenter and examining the dynamic indentation size and dynamic load value.The dynamic hardness of several typical materials such as 2A12 aluminum alloy,45steel,AZ31 magnesium alloy and AD95 alumina was tested with such dynamic hardness testing system.The results show that the dynamic hardness is higher than static hardness of all the materials used in the current investigation,i.e.,the materials have a higher deformation resistance during dynamic indentation.For metallic materials,the increment of hardness under dynamic conditions is strongly dependent on the crystal structure,and can reflect the ability of strain rate strengthening of materials.For the ceramic,AD95 alumina,the greater increase of dynamic hardness can be attributed to the inertial confinement around the indentation,which consequently inhibits the nucleation and growth of cracks.The dynamic hardness can efficiently characterize the dynamic mechanical properties of materials.
ZHANG Xiao-yong, GAO Hui-lin, BI Zong-yue, XU Xue-li, ZHANG Li-li. Effects of Welding Heat Input on Microstructure and Properties of Welding Seam in X80 Grade Welded Pipe[J]. Journal of Materials Engineering, 2010, 0(9): 66-70.
The effect of welding heat input on the toughness distribution and microstructure characterization of weld heat-affected zone(WHAZ)in the inside welding seam of X80 grade welded pipe was investigated by means of thermal simulation technique,microscopic analysis method and mechanical property testing.The results show that medium welding heat input(17-35kJ/cm)can produce good toughness in the weld coarse grained heat-affected zone(WCGHAZ)of welding seam of X80 pipeline steel.The toughness of WCGHAZ is the best when welding heat input is 20kJ/cm.But the toughness of WCGHAZ would become worse when welding energy input is less than 17kJ/cm and more than 35kJ/cm.Therefore,welding heat input at range of 17-35kJ/cm can be used as the recommended welding parameter in the outer welding process of X80 welded pipe.
GONG Yu-hui, LIU Ming, ZHANG Kun, HUANG Min, YI Lin-na, DAI Sheng-long. Effects of Different Corrosion Environments on Fatigue Property and Crack Growth Rate in 7475-T7351 Aluminum Alloy[J]. Journal of Materials Engineering, 2010, 0(9): 71-73.
The fatigue damage resistance to different corrosion environments in 7475-T7351 aluminum alloy was investigated.It was carried out by axial load fatigue test,fatigue crack growth rate test under different environments.The results show that corrosive environment affects the fatigue resistance of 7475-T7351 aluminum alloy dramatically,and the fatigue strength of smooth specimen in fuel tank or in 3.5%(mass fraction)NaCl solution decreases by 68% in comparision to room temperature,and the influence of different environments including water in fuel tank and 3.5%NaCl solution on the fatigue strength of materials is almost the same.The different corrosion environments and different temperature on low cycle fatigue in 7475-T7351 are less effective.The corrosive environment accelerates strongly the rate of fatigue crack propagation.The water in fuel tank and 3.5% NaCl solution all accelerate fatigue crack propagation by almost the same pattern.
KONG Gang, CHEN Jiu-long, LU Jin-tang. Effects of pH Value of Saturated Ca(OH)2 Solution on CaHZn Coating of Hot Dip Galvanized Steel[J]. Journal of Materials Engineering, 2010, 0(9): 74-79.
The change of the CaHZn layer and the corrosion behavior of the zinc coating in saturated Ca(OH)2 solution with decreased pH value from 9.0 to 12.0,which was as simulations of the pore solution with reduced pH value by carbon dioxide,were investigated.And the dissolving mechanism of CaHZn under the experimental condition was also discussed.The prepared galvanized samples with CaHZn coating were immersed in saturated Ca(OH)2 solution with pH value 9.0-12.0 for 30 days,then studied with scanning electron microscope(SEM),energy spectrum analysis(EDS),X-ray diffraction(XRD),Tafel polarization and electrochemical impedance spectroscopy(EIS).The results show that,with decreasing of pH value and increasing of the immersion time,the CaHZn decreases and the ZnO increases simultaneously.The entire surface of the sample is covered by the ZnO when pH value decreases to 9.0.As CaHZn is reduced and ZnO increases,the polarization resistance(Rp),the film resistance(Rc),penetration resistance(Rct)and the diffusion impedance(Ws)decrease,while the self-corrosion current(icorr)increases but still close to the passivation threshold 10-1μA/cm2.
LIU Jun-you, ZHANG Yi, JING Xu-ran, XU Zhen-hua. Effects of Si Contents on Corrosion Resistance of FeCrMnSi Alloy in Zinc Bath[J]. Journal of Materials Engineering, 2010, 0(9): 80-85.
A systematic study of corrosion behaviors of the FeCrMnSi alloys with different Si contents in pure zinc bath at 450℃ was carried out in order to better understand the effect of Si element on the growth of the Fe-Zn phases.The results show that the corrosion product of FeCrMnSi alloys in pure zinc bath is Fe-Zn intermetallic compounds.The thickness loss increases with increasing time.When the Si content up to 0.5%(mass fraction,the same as below),the corrosion behavior depends on the Mn element;when the Si contents up to 1.5%,the effect of Mn is reduced by the existence of Si,the δ phase has the maximum thickness,so the alloy shows the best corrosion resistance,and the corrosion rate is 3.05×10-3g·cm-2·h-1;when Si contents increase to 3%,there is also a lot of Si left besides reactioning with Mn,which leading to formation of loose structure of δ+η layers,so the alloy shows the worst corrosion resistance.
LI Xiao-bing, LIU Ying. Pretreatment of Electroless-deposited Silver on Medical Polyurethane[J]. Journal of Materials Engineering, 2010, 0(9): 86-90.
The surface pretreatment to electroless-deposited silver on medical polyurethane was studied,such as roughening,sensitizing and activating.Chromium trioxide and potassium permanganate were used as roughening solution,stannous chloride as sensitizing solution,silver nitrate as activating solution.The results show that the optimal roughening parameters are roughing temperature of 40℃,roughening time of 10min,chromium trioxide concentration of 80g/L,sulfuric acid and chromium trioxide mixture ratio of 2:1,the optimal sensitizing parameter is stannous chloride concentration of 10g/L.
JIA Li-xiao, ZHANG Yong-zhen, SUN Le-min, NIU Yong-ping, LI Jian, ZHAO Yan-wen. Friction and Wear Characteristic Comparison of Two Kinds of Carbon Material Under Condition of Current-carrying[J]. Journal of Materials Engineering, 2010, 0(9): 91-94.
Using C/C composite and carbon soaked by metal as pin samples and chrome bronze as disk samples,the friction and wear characteristics of two carbon materials at current-carrying conditions were compared by HST-100 friction wear tester.The result indicates that the friction and wear characteristic of C/C composite is influenced by velocity,load and current slightly.But the friction and wear characteristic of carbon soaked by metal is influenced by velocity,load and current intensively.The friction coefficient and wear rate of C/C composite is less than that of carbon soaked by metal significantly and C/C composite has excellent friction and wear characteristic under the condition of current-carrying.
FANG Wei-ping, CHEN Lun, SHI Yao-wu, YU Wen-jun, MAO Zhi-yong, TANG Zhen-yun. Research Development and Application of Damage Tolerance Titanium Alloy[J]. Journal of Materials Engineering, 2010, 0(9): 95-98.
The damage tolerance titanium alloys,such as Ti-6Al-4V ELI,TC4-DT,TC21 and TA15 ELI alloys,were summarized.The development process and the new study of damage tolerance titanium alloy were introduced.It pointed out that Ti-6Al-4V ELI alloy was successfully used in the airplane manufacture industry in foreign countries.However,TC4-DT,TC21 and TA15 ELI alloys were still under research in our country.The fracture toughness and fatigue crack propagation rate properties of TC4-DT,TC21 and TA15 ELI alloys were importantly discussed in detail.The lamellar microstructure was beneficial to improve the damage tolerance properties of titanium alloys.
