SHANG Xin-chun, ZHANG Zhi-biao. Characterization of Microscopic Damage in Aluminum Alloy Materials Under Intense Thermal Shock[J]. Journal of Materials Engineering, 2011, 0(2): 1-4,30.
The characterization of microdamage in 2A12 aluminum alloy materials after intense thermal shock was analyzed.The intense thermal shock for the aluminum alloy was experimentized by using laser drilling on the center of circle plate specimens.The metallurgical structure on the cross and longitudinal sections near the laser drilling hole of specimens was observed,and the micrographs of the material damage in heat affected zone was obtained by means of SEM.These micrographs reveal more complex conformation of microdamage around the drilling hole,such as microvoid group,extending intergranular microcrack along grain-boundary,growing cavity at trifurcate grain-boundary,fragmentized fissure zone,whitely shiny strip.The analysis indicated that a dominant cause to bring such microdamage is thermal wave effect on aluminum alloy material which generates from intense thermal shock when laser drilling.
LI Xiao-fei, ZHANG Qi, XIANG Min, ZHANG Wen. Study of a Simulated and Accelerated Corrosion Method for the Carbon/Epoxy Composite[J]. Journal of Materials Engineering, 2011, 0(2): 5-9.
A simulated and accelerated corrosion test method for the carbon/epoxy composite was investigated,based on the marine atmosphere.According to the local meteorological data,a primary simulated and accelerated corrosion method has been obtained.Through the corrosion test,the carbon/epoxy composite was destroyed extensively.In order to get further information,the mechanical test and micro-morphology observation(SEM) were carried out.The results show that the radiation,temperature and/or humidity could cause extensive corrosion to the surface and interior of the carbon/epoxy composite and make an attack to the interface between matrix and carbon fiber.By the comparison with the results of the natural environment corrosion,it is confirmed that the simulation of the corrosion test method is relatively good.
JI Ling-kang, ZHANG Wei-wei, GAO Hui-lin, LI He-lin. Continuous Cooling Transformation of X100 Pipeline Steel[J]. Journal of Materials Engineering, 2011, 0(2): 10-16.
CCT curve of the X100 pipeline steels was established by thermodilatometric analysis method,and then it was analysed through hardness test,OEM,SEM and TEM observing.The CCT curve and the rule of phase transformation at different cooling conditions were investigated profoundly,and the structure style and its typical characters of the X100 pineline steels was discussed which tremendously helped understanding the relationship of the structure and performance and provided an important reference for the industry applications.
LÜ Xiang-hong, ZHAO Guo-xian, WANG Yu, ZHANG Jian-bing, XIE Kai-yi. SSC Resistance of Super 13Cr Martensitic Stainless Steel[J]. Journal of Materials Engineering, 2011, 0(2): 17-21,25.
H2S stress corrosion cracking(SSC) behavior of super 13Cr martensitic stainless steel at the simulated and standard environments has been studied with four-point bent test,electrochemical measurement as well as Scanning Electron Microscopy(SEM) analysis methods.The results show that the super 13Cr martensitic stainless steel behaves a high SSC susceptibility at the standard environments,and the cracks stem from surface corrosion pits because of the occurrence of H2S and Cl-making the pitting potential of super 13Cr martensitic stainless steel decreased significantly.While at the simulated environments,the SSC susceptibility of super 13Cr martensitic stainless steel decreased,and no cracks are found on the surface of the test specimen.
ZOU Tian-chun, FENG Zhen-yu, ZHAO Nai-qin, SHI Chun-sheng. Microwave Absorbing Properties of Activated Carbon Fibers/Epoxy Resin Composites[J]. Journal of Materials Engineering, 2011, 0(2): 22-25.
Microwave absorbing properties of the composites containing ACFs were investigated.The results show that the absorbing performances of the composites containing ACFs are affected greatly by the fiber contents and distribution in the absorbing layer.In this research,When ACF contents(mass fraction) of four structure layers in the absorbing layer are 0.2%,0.4%,0.6% and 0.8%,the composite has a reflection loss below-10dB in the frequency range from 4.2-18GHz,and the maximum absorption reaches-26.6dB at 7.12GHz.
HU Yan-hui, ZHONG Qun-peng, ZHANG Zheng, HAN Bang-cheng. Effect of Ultrasonic Fatigue Testing Method on Fatigue Properties and Crack Initiation Mechanism of S06 Steel[J]. Journal of Materials Engineering, 2011, 0(2): 26-30.
To research the effect of ultrasonic fatigue method on fatigue properties and initiation mechanism,fatigue properties of S06 steel were tested by using ultrasonic fatigue testing machine and high-cycle fatigue testing machine.Fatigue life of ultrasonic fatigue specimens is longer than high-cycle fatigue specimens,and it may be attributed to b.c.c.crystals structure of S06 steel and chemical reaction at crack tip.Fatigue cracks of ultrasonic fatigue specimens originate from surface and cracks of high-cycle fatigue specimens originate from both surface and interior.The effect of ultrasonic fatigue method on initiation mechanism may be attributed to looseness of surface residual stress during ultrasonic fatigue testing.
ZHANG Ju-hua, WANG Zhen, ZHANG Hong-yan, SU Zheng-tao. Molecular Structure and Properties of Hydrogenated Nitrile Rubber[J]. Journal of Materials Engineering, 2011, 0(2): 31-34,51.
A relationship of molecular structure and physical properties at low and high temperatures of hydrogenated nitrile rubber(HNBR)was investigated by Infrared(IR)Spectroscopy,Differential Scanning Caloricity(DSC)and Thermo Gravimetric Analysis(TGA).It is shown that HNBR has characteristic peak of the(CH2)n(n>4) in the backbone at 720-730cm-1 for identified HNBR from NBR.The initial decomposition temperature rose with the increase of the acrylonitrile content and hydrogenation.It is also concluded that the higher acrylonitrile content,the higher Tg,tensile strength and compression set of HNBR,which could be attributed to the crystallization caused by more content of repeat units.
LI Wei, GAO Jia-cheng. Effects of Nd on Microstructure and Properties of Extruded Mg-Y-Nd-Zr Alloy[J]. Journal of Materials Engineering, 2011, 0(2): 35-41.
Effects of Nd on microstructure and mechanical properties of extruded Mg-5.0Y-xNd-0.6Zr(x=0,1.0,2.6,4.2,mass fraction/%,the same below) alloy were investigated by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD) and tensile testing.The results showed that with addition of Nd,the banding particles of β and Mg24Y5 phase in the extruded alloy increased,which promoted the nucleation of dynamic recrystallization,the volume fraction of recrystallization advanced,and the average grain size of recrystallization could be refined from 4.5μm to 2.6μm.The tensile strength and yield strength of extruded alloy increased with increment of Nd,the maximum values of them were 303MPa and 262MPa respectively.The elongation and section shrinkage conspicuous decreased from 24.7% and 39.9% to 12% and 16.7% with increasing Nd content.The extruded alloy displayed better strength and plasticity at Nd content of 2.6%.
SUN Yu-wei, WANG Shu-bin, ZHANG Jian. Effects of CBS Coating on Dielectric Properties of Porous Si3N4 Ceramic at High Temperature and High Frequency[J]. Journal of Materials Engineering, 2011, 0(2): 42-45.
Compact moisture proof coating was fabricated with CaO-B2O3-SiO2(CBS) glass ceramic on the porous silicon nitride substrate by sol-gel method.The dielectric constant and dielectric loss from 7.3GHz to 18.4GHz were tested from room temperature to 1200℃ by applying factor cylindrical cavity working in multimode before and after sealing.The result shows that,after coating,the dielectric constant is slightly higher and the fluctuation of dielectric loss decreases with frequency.At frequency of 9.2GHz the temperature coefficient of dielectric constant increases after coating.The dielectric loss is decreased by 60% or more at room temperature after coating;the temperature stability of dielectric loss is improved by coating,and the demands of dielectric properties of radome are well satisfied.
PENG Jian, ZHOU Chou, TAO Jian-quan, PAN Fu-sheng. Gas Tungsten Arc Welding of Dissimilar Magnesium Alloys as AZ31 with AZ61[J]. Journal of Materials Engineering, 2011, 0(2): 46-51.
The AZ31 and AZ61 plates in 3 mm thick plates are welded with AZ31 and AZ61 welding wires by TIG method.The influence of welding wires on the strength of welded joints of AZ31 and AZ61 magnesium alloy plates was investigated.The appearance shape,microstructure and patterns of welded joints were analyzed as well as the mechanical properties test by means of OM,SEM,X-ray diffraction and etc.The result showed that the appearance shape was good with weather AZ31 or AZ61 welding wire.The welded zone was identified to be composed of α-Mg and β-Mg17Al12 phases.The heat affected zones exist both in AZ31 and AZ61 joints,with grains coarser than base metal.Relative to AZ61 welding wire,using the AZ31 welding wire tends to get a coarse grain region of little width,and a fracture point closer to the center line of welding seam,with tensile fracture strength of 161MPa leading to a 64% strength of the AZ31 base metal.With the AZ61welding wire,a coarse grain region of more width and a fracture point a little far from the center line are happened,the strength of the joints reaches to 210MPa,84% of that of its AZ31 base metal.
HU Mao-liang, JI Ze-sheng, CHEN Xiao-yu, WANG Qu-dong. Study on Microstructure and Mechanical Properties of AZ91D Magnesium Alloy Fabricated by Hot Extrusion from Die-casting Scraps[J]. Journal of Materials Engineering, 2011, 0(2): 52-55,59.
A method for recycling AZ91D magnesium alloy scraps directly by hot extrusion was studied.Effect of extruding temperature on microstructure and mechanical properties was analyzed and the fracture behavior was discussed.The results indicated that the interfaces of original individual scraps were not identified in the recycled specimens when the scraps were extruded with the extruding temperature of 450℃.The recycled specimens consisted of fine grains due to dynamic recrystallization.Ultimate tensile strength and elongation to failure increased with increasing the extruding temperature in the range of 350-450℃.Recycled specimens with the extruding temperature of 450℃ showed higher ultimate tensile strength of 336.56MPa and higher elongation to failure of 11.02%.Bonding states of original individual scraps have an important effect on mechanical properties of recycled specimens.
CHEN Bo, XIONG Hua-ping, SHEN Qiang, WANG Chuan-bin, LI Jun-guo. Preparation of Ti/TiAl/Al System Graded Material with a Density Gradient by Brazing Method[J]. Journal of Materials Engineering, 2011, 0(2): 56-59.
The Ti/TiAl/Al system functionally graded material was fabricated with two-step brazing method.Firstly,the vacuum brazing of TC4 to TiAl was carried out using Ti-Zr-Cu-Ni-Co brazing filler at 960℃ for 10min.Secondly,with pure-metal powder of Al-25Cu-5Si,the joint of TiAl/LF21 was brazed at 590℃ for 10min.As a consequence,a thin diffusion layer near TiAl base metal was formed in TC4/TiAl joint.In particular,the transient phases of Ti3Al and Ti2Al were found to be formed within the 50μm-thickness brazing seam in the TC4/TiAl joint.The density of TC4/TiAl/LF21 FGM changes quasi-continuously from 4.5g/cm3 to 3.8g/cm3 and to 2.7g/cm3 in its thickness direction.
YUE Chong-xiang, ZHANG Li-wen, RUAN Jin-hua. Pass Design and 3D Simulation for the Rolling Process of φ70-80 Bearing Steel Rod[J]. Journal of Materials Engineering, 2011, 0(2): 60-64.
A pass system to produce φ70-80 bearing steel rod by using 300mm billet was developed.With the aid of software MSC.Marc and its user subroutine,3D FE models for the rolling process coupled with the microstructure evolution model of GCr15 steel were established to simulate the deformation of rolled piece and the rolling force at every pass.Meanwhile,the evolutions of temperature,strain,strain rate and austenite grain size in the rolled piece were obtained.The work realized the virtual computer rolling before practical rolling of rod.
LI Qing-da, LIAN Fa-zeng, YOU Jun-hua, SUN Yun, CHEN Yu-lan. Study on Preparing Process of Fe-Si-Al Composite Magnetic Powder Cores[J]. Journal of Materials Engineering, 2011, 0(2): 65-68.
Fe-Si-Al composite magnetic powder core was prepared by compression molding,and the effect of the annealing condition and insulation coating on magnetic properties of composite magnetic powder core was studied.Such results are concluded from experiment.Annealing following compaction could effectively promote magnetic properties of Fe-Si-Al magnetic cores.Increasing annealing temperature increases effective permeability and decreases hysteresis loss of specimens,and over-annealing(>660℃) could degrade the insulation between powder particles and deteriorate magnetic properties.The optimum annealing temperature is 660℃.The magnetic annealing is a new effective method that decreases loss of Fe-Si-Al magnetic powder core,and the loss of magnetic powder cores in the magnetic annealing is smaller than one in annealing.Increasing dielectric content could effectively reduce eddy current loss of Fe-Si-Al magnetic powder core and bring negative influence of decreasing the real part of permeability.The optimum dielectric content is 0.7%(mass fraction).
XU Guang-liang, CHEN Guo-qing, ZHOU Wen-long, FU Xue-song, REN Xiao, SUN Zhong-gang. Effect of Equal Channel Angular Extrusion on the Microstructure and Mechanical Properties of AZ31 Magnesium Alloy[J]. Journal of Materials Engineering, 2011, 0(2): 69-72.
The microstructure and mechanical properties of electromagnetic continuous cast AZ31 magnesium alloy processed by equal channel angular extrusion(ECAE) and two-step ECAE in route A were investigated.The results showed that the degree of grain refinement increased with the increasing pass number.The elongation was improved,but the yield strength and tensile strength decreased.On the contrary,after two-step ECAE much finer grain size was obtained.The elongation,the yield strength and tensile strength were enhanced compared with the sample of as-extruded.The change of the elongation,the yield strength and tensile strength is related to the increase of dislocation density.
XIAO Xiang, LIU Guo-quan, HU Ben-fu, HU Jia-xue, KANG Ren-mu, ZHENG Xiao. The Influence of Cold Deformation to 12Cr Ferritic/Martensitic Steel Recovery and Recrystallization Process[J]. Journal of Materials Engineering, 2011, 0(2): 73-78.
A new high Cr low activation ferritic/martensitic(F/M) steel used for candidate cladding tube in supercritical water reactor has developed,research for the influence of cold deformation to its ferrite and lath martensite in the recovery and recrystallization process.The results showed that cold deformation can promote the recrystallization of lath martensite in different degrees,annealing at 780℃ after 10% cold deformation occurs only recovery process,martensite lath is merged with transfer,however,annealing at 780℃ after 60% cold deformation,tempered martensite occurs rapid recovery and recrystallization.After the same amount of cold deformation,tempered martensite recrystallization will give priority to the ferrite in high temperature tempering process.12% δ-ferrite will not significantly delay the re-crystallization process of martensite,after long tempering,the ferrite grains are converted into secondary recrystallized ferrite grains.The final microstructure is fine grain ferrite.
SI Hong-juan, XU Bin-shi, WANG Hai-dou, MA Guo-zheng. Tribological Properties Research of Nano-electro-brush Plating In Layer in Vacuum Radiation Environment[J]. Journal of Materials Engineering, 2011, 0(2): 79-83,86.
Making use of nano-electro-brush plating technology,the layer In was prepared on working lining.With scanning electron telescope(SEM) and X-ray diffraction(XRD),surface,grinding crack pattern and elemental composition of In layer after exposed in air,in vacuum,atomic oxygen and ultraviolet radiation are analyzed.Vacuum friction and wear equipment model CZM was applied for testing tribological properties under dry friction condition in environments such as air,vacuum,atomic oxygen and vacuum ultraviolet radiation.Outcome shows in normal state,metal In has good chemic stability,erosion resistance and solid lubricity and the atomic oxygen and vacuum ultraviolet’s effect on it is very limited.But the tribological properties of lubricant coating prepared with nano-electro-brush plating technology are poor because of degradation of density and superficial smoothness caused by air-bleeding.So as long as through proper process method and enhancing In layer’s forming quality,soft metal In coating should have decent prosperity in future space equipments and arming.
WANG Qiang, WANG Xin, GAO Yu-kui, SONG Ying-gang. Effect of Strengthened Hole on the Fatigue Life of TC18 Titanium Alloy[J]. Journal of Materials Engineering, 2011, 0(2): 84-86.
In order to improve the fatigue property of hole on substrate and weld TC18 titanium alloy.The TC18 titanium alloy specimens with a hole on substrate and weld were prepared.The influence of residual stress and surface integrity brought by Cold Expansion Hole(CEH) and Shot Peening Hole(SPH) process the specimens was studied.The result showed that,surface residual stress was higher than-300MPa after SPH process,the SPH process has obvious strengthening effect,the fatigue crack sources generate at the beneath of surface after SPH process,it can improve tension-tension fatigue property of TC18 titanium alloy specimen,which has a hole on the weld,and the specimen’s average fatigue life can increase by 6 times.
WANG Jian-sheng, MENG Hui-min, YU Hong-ying, SUN Dong-bai, FAN Zi-shuan. Characterization of Electro-spark Deposition WC-15Co Coating on Cast Steel Roll[J]. Journal of Materials Engineering, 2011, 0(2): 87-91,96.
Using a new type electro-spark deposition,WC-15Co electrode was deposited on the surface of cast steel roll by electro-sparking deposition(ESD).The microstructure and wear resistance of the coating were investigated.The results show that the coating consists of Fe3W3C,Co3W3C,Fe2C and Fe phases.The coating is well metallurgical bonded with cast steel roll substrate.The Fe3W3C,Co3W3C and Fe2C phases distribute in the coating dispersedly,with the extra-fine structure for the phases in some area.The average hardness of the coating is 660HV.The coating has good wear and the average wear resistance rate is 2.7 of that of the cast steel substrate.The wear mechanism is adhesion wear,fatigue wear,oxidization wear and abrasive wear.Fine hard phases distributed in the coating dispersedly are the main factors leading the high hardness and wear resistance of the coating.
XU Qiao-yu, ZHOU Wei. Microstructure and Corrosion Electrochemical Behavior of Hot-dipped Zn-Ni-V Coating[J]. Journal of Materials Engineering, 2011, 0(2): 92-96.
The hot-dipped Zn-0.05%Ni-0.05%V coating was gained by adding a small amount of Ni and V in the zinc bath.The microstructure of Zn-0.05%Ni-0.05%V coating and corrosion process of the coating in 5%NaCl aqueous solution were investigated by SEM and electrochemical impedance spectroscopy(EIS).The results show that,the addition of 0.05% V to the Zn-0.05%Ni bath can effectively restrain the Fe-Zn reaction and obviously inhibit the growth of ζ phase in the coating.Compared with Zn-0.05%Ni coating,Zn-0.05%Ni-0.05%V coating following immersion for 20 min was of larger electrochemical impedance.The impedance of the Zn-0.05%Ni-0.05%V coating was found to sharply decrease in the first two days of immersion in relation with the break down of the oxide layer.As the sample surface covered with corrosion products with the immersion time up to 8 days,the impedance spectra for the coating consisted of two capacitance loops and the Warburg diffusion impedance at the low frequency.Moreover,the impedance increased gradually with increasing the immersion time.According to the characteristic of EIS in the corrosion process,EIS of the coating at different immersion time was simulated using appropriate equivalent circuit.The results show that,after immersing 8 days,the Y1,the n1 and the diffusion resistance WR decreased,the R1 of corrosion products increased gradually.The double-layer capacitance C2 and the polarization resistance R2 of the corrosion reaction have no substantial regularity with prolonging the immersion time.
