2006 Vol. 26, No. 3

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Effect of SiO2 Non-Metallic Inclusion on Micro-Mechanical Behavior of Nickel-Base P/M Superalloy
ZHOU Xiao-ming, WANG Wu-xiang, WANG Xu-qing, TANG Ding-zhong, YAN Ming-gao
2006, 26(3): 1-6.
[Abstract](1378) [PDF 1660KB](285)
Abstract:
The effect of SiO2 non-metallic inclusion on fracture initiation and propagation in FGH95 superalloy by SEM in-situ tension and fatigue experiments was investigated.The results show that the fractures were easily initiated from inclusion,and propagated into inclusion normal to or about 45° with main stress axis during in-situ tension process.After propagating into the matrix,the fracture went along the vertical plane with obvious slipping zones around it.The fractures were initiated at the interface between the inclusion and the matrix,and propagated into the matrix about 45° with main stress axis during in-situ fatigue process.And then,the fractures propagated into the matrix normally until the specimen was ruptured.The fractures show different morphological characters during the two processes due to the matrix with thin γ′ phases near the inclusion.
Effect of Cooling Rate During Solidification on Microstructure of Cast Ni-Base Superalloy K417G
ZHENG Liang
2006, 26(3): 7-11.
[Abstract](1483) [PDF 1947KB](343)
Abstract:
The solidification tests were carried out with different cooling rate on cast Ni-base superalloy K417G.The effects of cooling rate on microstructure were investigated by analyzing solidified specimens using optical and quantitative metallography.The relationship between cooling rate and average dendritic spacing was determined by the method of linear regression.The results indicate that higher cooling rates are prone to form finer dendrites,MC carbides and(γ+γ′) eutectic.Cooling rate has little effect on the volume percent of MC but has great influence on that of(γ+γ′) eutectic,excessive high or low cooling rates all result in an increase in amount of(γ+γ′) eutectic.The relationship between the average dendritic spacing(λ/μm) and cooling rate(V/℃·s-1) for K417G can be described by the following equations: λ=85.1V(-0.35).Consequently,it is possible to determine the cooling rates of different part of castings such as root and leading or trailing edge of blade by measuring the dendritic spacing.
Effect of Aging at 1100℃ on Microstructures of DM02 Alloy
LI Qing, SONG Jin-xia, XIAO Cheng-bo, QU Shi-yu, WANG Ding-gang, HAN Ya-fang
2006, 26(3): 12-15.
[Abstract](1379) [PDF 1616KB](180)
Abstract:
The effect of aging at 1100℃ on microstructures of a new developed nickel base die material named DM02 have been studied in this paper.Specimens were exposed at 1100℃ for 100h,200h and 500h respectively.The effect of aging time on microstructures of the alloy were analyzed by X-ray diffractionmeter and scanning electron microscope.New precipitated phases were identified by transaction electron microscope.The result showed that carbide reactions of forming M6C carbide have occurred in the alloy during aging,(amounts) of M6C carbides increased with aging time,and coarsening of γ′were also found in this study.Most of the precipitated M6C distributed in interdendritic areas with shapes of needle or block,while only few of them distributed in dendritic areas and mainly with needle shape.
Influence of W Concentration on Microstructure and Properties of Single Crystal Nickel Base Superalloy
TIAN Su-gui, DU Hong-qiang, WANG Chun-tao, MENG Fan-lai, SHUI Li, HU Zhuang-qi
2006, 26(3): 16-19.
[Abstract](1400) [PDF 546KB](377)
Abstract:
By means of the measurement of the creep curves and microstructure observation,an investigation has been made into the influence of the element W concentration on the microstructure and properties of single crystal nickel-based superalloys.Results show that the superalloy with 4% W in Ni-Al-Cr-Ta-Co-W-5.5%Mo systems displays a better creep rupture lifetimes under the applied stress of 200 MPa at 982℃,but the ones of the alloy is obviously decreased with the increase of the element W concentration up to 6%.The fact that the m phase is precipitated in the superalloy with 6%(wt) W during aged results in the appearance of the poor regions for the refractory elements.This is one of the main reasons for reducing the creep rupture lifetimes of the supralloy.The needle-like μ phase is precipitated to be parallel or perpendicular to each other along the 110 orientation,and grown into the slicelike morphology along the {111} planes.
New Ni3Al-Based Directionally-Solidified Superalloy IC10
ZHAO Xi-hong, HUANG Zhao-hui, TAN Yong-ning, ZHANG Qiang, YU Qian, XU Hui-bin
2006, 26(3): 20-24.
[Abstract](1583) [PDF 1255KB](481)
Abstract:
A new alloy named as IC10 for aero-engine vane with a service temperature of 1100℃ is introduced in this paper.The(alloy′s) composition is characterized by no Ti,1.5wt% Hf and higher than 19wt% of Al+Ta+Cr.This alloy exhibits superior oxidation resistance and excellent castability.Furthermore,its stress-rupture strength is at the same level with abroad first-generation DS superalloy.The carbides of IC10 alloy is mainly composed of TaC and HfC.Moreover,the formation of M6C is suppressed by the secondary MC(2).The incipient melting temperature is increased by elemination of Ni5Hf through a pre-treatment at 1180℃ for 2h.The low cycle fatigue life of IC10 alloy at 700℃ and 980℃ was obtained respectively.The thermal-mechanical fatigue test under the condition of 600℃ 1100℃ was conducted,and the thermal-mechanical fatigue life of IC10 alloy with in-phase and out-of-phase was presented.The aero-engine high-pressure vanes that were made of IC10 alloy is being under PRFT.
Investigation of Effect Mechanism of Hafnium and Zirconium in High Temperature Materials
ZHENG Yun-rong, CAI Yu-lin, RUAN Zhong-ci, MA Shu-wei
2006, 26(3): 25-34.
[Abstract](2915) [PDF 2039KB](981)
Abstract:
Hafnium and zirconium can promote the formation of (γ+γ′) eutectic,MC(2) carbides,M2SC sulfides and Ni5M phases in superalloys,change script MC and M3B2 into blocky shape and delay the initiation and propagation of cracks by cleaning the free state sulfur at grain boundary and interdendritic regions and strengthening their cohesion.Both of elements Hf and Zr increase the stress rupture strength and ductility of cast superalloys at intermediate temperature and also improve the tensile strength and ductility at room temperature.Hf and Zr strict the precipitation of secondary carbides,such as M23C6 and M6C,therefore stabilize the microstructure of alloys during long-term exposure at elevated temperature.However,Hf and Zr lower the incipient melting temperature of superalloys.The melting of Ni5Hf or Ni5Zr phases may be considered as one of the main factors affecting incipient melting.By means of a pretreatment at 1150℃/8h,Ni5Hf phase can be eliminated in two ways: The reaction Ni5Hf+ γ(C) →MC(2)+ γ or solid solution.Hafnium may narrow down the range between temperature lost the interdendritic capillary feeding action and solidus,as well as may decrease the liquid content necessary for linking the interdendritic pools in the late solidification.The Hf-rich melts in interdendritic zone have superior fluidity,wettability and skin effect.These are the factors in increasing castability and weldability of Hf-containing superalloys and in decreasing tendency of hot tear.The high chemical activity of skin Hf-rich liquid promotes the formation of a thin layer of Hf2O on the surface of castings.Hf and Zr are the melting point depressant in the interlayer alloys used for brazing.It may be considered that dendrites formed in the early solidification are brazed by interdendritic Hfor Zr-rich melts.Eventually,the Ni-18.6Co-4.5Cr-4.7W-25.6Hf and Ni-10Co-8Cr-4W-13Zr alloys were developed according to the composition of Hf-or Zr-rich melts,and the Si-or B-free-bonding for single crystal superalloys could be realized.Studying the Hf-rich melts also leads to the development of unidirectionally solidified lamellar Ni3Al/Ni7Hf2 eutectic.The suitable compositions for these eutectic in situ composites are Ni-5.8Al-32Hf and Ni-4Al-26Hf-8Cr-4W.The results showed that the lamellar Ni3Al/Ni7Hf2 eutectic aligned parallel to the direction of solidification were prepared with temparature gradient G=250℃·cm-1 and solidification rate R=5μm·s-1 for the ternary alloy,and G=350℃·cm-1 and R=1μm·s1 for multicomponent alloy.
Disappearance of Ni3Nb Primary Phase in Hypereutectic Alloy of Ni-24.19wt% Nb at Abruptly Decreasing Growth Rate under Directional Solidification
LI Shuang-ming, JIANG Bing-lun, MA Bo-le, LIU Lin, FU Heng-zhi
2006, 26(3): 35-40.
[Abstract](1426) [PDF 862KB](335)
Abstract:
Directionally solidified microstructures of Ni-24.19wt%Nb hypereutectic alloy were investigated at the growth rate of 10μm/s,and the abruptly decreasing growth rate from 10 to 1μm/s.The results show that the microstructure consists of Ni3Nb primary phase and eutectic(Ni+Ni3Nb),in agreement with the theoretical calculation results at the growth rate of 10μm/s.After the solidified distance of 20mm,the growth of Ni3Nb primary phase achieves the quasi-steady state.At the abruptly decreasing growth rate from 10 to 1 μm/s,the volume fraction of Ni3Nb primary phase firstly increases,attributing to the change of interface composition,and then decreases to zero.Finally,the off-coupled growth microstructure changes to the coupled growth eutectic due to the competitive growth of interface temperature between Ni3Nb primary phase and eutectic(Ni+Ni3Nb).The disappearance of Ni3Nb primary phase does not simultaneously occur and mainly originates from the side to the center of the sample.
Effect of Coatings on Microstructure and Hot Corrosion Resistance of Ni3Al Base Alloy IC6AE
ZHANG Chun-xiao, LI Shu-suo, HAN Ya-fang
2006, 26(3): 41-46.
[Abstract](1395) [PDF 1419KB](302)
Abstract:
Al-Si and NiCr-CrAl coatings for an equiaxed Ni3Al base alloy IC6AE were prepared respectively by the slurry and powder pack cementation methods.The hot corrosion resistance tests for the three kinds of IC6AE specimens with the above two coatings and without coating were carried out by coating salt(5wt%NaCl+95wt%Na2SO4) corrosion at 900℃ for 20h,40h,60h,80h and 100h.The experimental results showed that NiCr-CrAl coated specimens had the best hot corrosion resistance compared with the specimens of Al-Si coating and without coating,and Al-Si coating had no evident hot corrosion resistance improvement compared with the specimens without coating. Microstructure analysis showed that the specimens of alloy IC6AE without coating were corroded seriously after coating salt corrosive test at 900℃ for few hours.After 100h test,a porous loose corroded layer which was composed of oxide of Mo and Ni formed,and it was obvious that this kind of layer had no protective properties.While in the case of Al-Si coated specimens,the corroded layer on the specimens′ surface composed of not only large amount of Mo and Ni oxide but also small amount of Al2O3 and NiAl3 phases,which may have some protective effect for the specimens.For the situation of NiCr-CrAl coated specimens,the continuous and compact layer composed mainly of a large volume fraction of Al2O3 and NiAl2O4 phase and a small amount of oxide of Mo and Ni,which had better protective effect for the alloy,and therefore the hot corrosion resistance properties were improved greatly.
Microstructure and Mechanical Properties of Nb Based Ultrahigh Temperature Alloy Directionally Solidified by EBFZM
GUO Xi-ping, GAO Li-mei
2006, 26(3): 47-51.
[Abstract](1625) [PDF 1097KB](327)
Abstract:
The microstructure and mechanical properties including room temperature fracture toughness Kq,tensile strength σb and elongation δ at 1250℃ of the Nb based alloy directionally solidified in an electron beam floating zone melting(EBFZM) furnace have been evaluated.The microstructure was primarily composed of Nb solid solution(Nbss),α-(Nb)5Si3 and(Nb)3Si phases.After directional solidification with the moving rate of electron beam gun R being respectively 2.4,4.8 and 7.2 mm/min,the primary Nbss dendrites,Nbss +(Nb)5Si3/(Nb)3Si eutectic colonies(lamellar or rod-like) and separated Nb silicide plates aligned along the longitudinal axes of the specimens.When R=2.4 mm/min,the best directional microstructure was obtained.Both of the tensile strength σb at 1250℃ and room temperature fracture toughness Kq were improved significantly by the directional solidification.The maximum σb occurred for the specimens with R=2.4 mm/min and was about 85.0 MPa,meanwhile,the Kq was about 19.4 MPa·m1/2.
Evaluation of Grain Growth of Spray Formed Superalloy GH742y
XU Wen-yong, LI Zhou, ZHANG Guo-qing, YUAN Hua, LI Zheng-dong, YAO Rui-ping, TIAN Shi-fan, XU Shi-bing
2006, 26(3): 52-55.
[Abstract](1355) [PDF 355KB](285)
Abstract:
The influence of solution temperature on the phase structure and grain size of spray forming GH742y N2-atomized has been investigated,and,the inhibited effects of the second phase on grain growth have also been studied.The results indicate very little coarsening and good stability of grains in GH742y alloy spray formed by nitrogen atomization.The limiting ultimate grain size of the as spray formed and HIPed alloy was about 40μm.The γ′ solvus temperature of spray formed GH742y has determined to be about 1127℃.The dispersed MC-type carbonitrides inhibit grain coarsening during solution treatment above γ′ solvus temperature.Gladman equation can estimate limiting ultimate grain size in HIPed preform N2 atomized.
Long Time Thermal Stability of Superalloy GH909 at 700℃
ZHAO Yu-xin, ZHANG Shao-wei
2006, 26(3): 56-59.
[Abstract](1454) [PDF 633KB](313)
Abstract:
This paper presents a study of the microstructure and mechanical properties of alloy GH909 exposed at 700℃ for up to 2000h.The tensile strength of alloy GH909 significantly degraded with the initial exposure at 700℃ for 500h and thereafter remained essentially constant for up to 2000h exposure.The notch rupture life at 650℃/510MPa increaseed with the initial 100h exposure and then began to lose its notch rupture life on further exposure.The variation of tensile strength and stress-rupture life were correlated with the change of microstructure.
Study on the Microstructure of 9Cr13Mo3Co3Nb2V Martensite Stainless Steel
LIANG Zhi-kai, FENG Shen-tian, LI Dong-ling, LU Cui-fen
2006, 26(3): 60-65.
[Abstract](1456) [PDF 603KB](328)
Abstract:
9Cr13Mo3Co3Nb2V steel belongs to dispersion-hardening martensitic stainless steel with high hardness,which can gain high hardness(≥59HRC) and high anti-wearing through heat treatment.In the paper the microstructure of 9Cr13Mo3Co3Nb2V in different heat-treatment has been studied.The type,content and structural composition of separated phase in different heat-treatment(tempered,quenched and standardize heat-treated) have been investigated using physic-chemical analytic technology,the weight distribution of separated phase in different grain-size of different heat-treated 9Cr13Mo3Co3Nb2V has been analyzed using SAXS.
Effect of Al Content and Cooling Rate on Thermal Stability of Fully Lamellar Microstructures in TiAl Alloys
LI Zhen-xi, QI Li-chun, HUANG Xu, CAO Chun-xiao
2006, 26(3): 66-70.
[Abstract](1490) [PDF 2022KB](230)
Abstract:
The effects of Al content and continuous cooling rate on thermal stability of fully lamellar(FL) microstructure in TiAl alloys at 1150℃ were investigated.For the binary TiAl alloys with 46at%~48at%Al,the higher the Al content is,the more serious the γ dendritic segregation is and the less stable of as-cast FL microstructure is.The thermal stability of coarse lamellar microstructure in Ti-48Al alloy formed by furnace cooling from the α single phase field is superior to that of fine lamellar microstructure formed by air cooling.For the fine lamellar microstructure,the lamellar discontinuous coarsening occured at the grain boundaries,meanwhile the interfaces between the Widmnstatten lamellar colonies within the grains and the lamellar matrix also become the original sites of discontinuous coarsening.
Fatigue Crack Growth Characteristics of Fine Structures of SP700 and Ti-6Al4V Titanium Alloys
CAI Jian-ming, XU Chao, HAO Meng-yi, HUANG Xu, MA Ji-min, CAO Chun-xiao
2006, 26(3): 71-74.
[Abstract](1541) [PDF 744KB](339)
Abstract:
Fatigue crack growth rate and fracture characteristics of SP700 and Ti-6Al-4V titanium alloys with fine-grained structures obtained through a new thermo-mechanical process were studied. The results showed that SP700 had lower fatigue crack growth rate than that of Ti-6Al-4V,especially at high ΔK.SP700 and Ti-6Al-4V showed mainly identical wave slip fatigue fracture characteristics.
Study on Microstructure and Oxidation Resistance Properties at Elevated Temperature of FeCrAl Coatings Produced by High Velocity Arc Spraying
WANG Xue, ZHANG Jin-li, ZHOU Han-xiang, MIAO Ka-sha
2006, 26(3): 75-78.
[Abstract](1404) [PDF 767KB](342)
Abstract:
FeCrAl coatings were prepared on low carbon steel substrate by high velocity arc spraying(HVAS)technology.The oxidation performance of coatings at elevated temperature was tested,microstructures of the sprayed and oxidized coatings were investigated.Results indicated that the as-sprayed coating was consisted of Fe-Cr amorphization mainly,together with crystallic phases such as Cr1.3-Fe0.7O3 and Fe-Cr solution crystals,which could be concluded that a very high cooling rate was obtained during HVAS process.The great mass of Al was oxidized during the spraying,which was existed in form of Al2O3.The oxidation resistances of coatings at elevated temeprature was much higher than that of 12Cr1MoV steel and approximately follows that of T91 steel.The excell oxidation resistances of FeCrAl coating was due to the chromium oxide pretective film would be formed at layers of the coating, moerever it was closely relation to the formation of Fe-Cr amorphization with high resistances to oxidizing.After being oxidatized at 800℃ for 260h,partial amorphization structures were crystallized and transformed into the fine Fe-Cr crystallic phase.
Study on Triple Aging and Mechanical Properties of High Strength Al-Cu-Li-X Aluminum Lithium Alloy-2A97
YUAN Zhi-shan, LU Zheng, XIE You-hua, DAI Sheng-long, LIU Chang-sheng
2006, 26(3): 79-82.
[Abstract](1326) [PDF 1102KB](367)
Abstract:
The effect of triple aging-T6I6 and RRA and their modified processes on mechanical properties of novel high strength Al-Cu-Li-X aluminum-lithium alloy,2A97,was investigated through tensile test.The results showed that T6I6 and RRA yielded high strength and ductility as the same level as the peak aging,and their modified processes produced highest strength due to introduced plastic deformation.The microstructures consisted of δ′ phase,θ″/θ′ phase and T1 phase for triple aging and their modified processes.The number density of δ′ phase was changed by introduced plastic deformation which accelerated precipitation or reversion of δ′ phase after double aging,and the precipitation of T1 phase was promoted significantly.
Study of Metal Flow Behavior during Extruding with Inner Cone Punch
LI Feng, YUAN Shi-jian, LIU Gang
2006, 26(3): 83-87.
[Abstract](1439) [PDF 664KB](577)
Abstract:
For the defects such as dead zone and shrinkage cavity in conventional extrusion process,an inner cone punch was proposed to improve the metal flow behavior.Numerical simulations on extrusion process with and without the inner cone punch were carried out,and the division of deformation was proposed by employing the characteristic quantity such as Lode parameter and invariant of the deviator(J2).Numerical simulation results were tested by the 7050 aluminium alloy extrusion experiments,the results showed that,by employing the inner cone punch,velocity field distribution during extrusion process would be improved greatly,the risk in generation of dead zone was reduced remarkably,and shrinkage cavity would be avoided,therefore,the inner cone punch made the metal much easier of extruding.
Numerical Simulation of Temperature Distributions in Spray-Casting Clad Roll
WANG Yu, CUI Cheng-song, LI Qing-chun, ZHANG Guo-qing, WANG Wu-xiang
2006, 26(3): 88-92.
[Abstract](1268) [PDF 783KB](264)
Abstract:
Spray casting is an advanced manufacturing technology used to produce high performance clad rolls.However,the key problem of this new process is the difficulty of the interface bonding.The temperature distributions in the clad roll and its influencing factors were investigated through numerical simulation.The results show that the preheating temperature,the traveling speed and the spraying rate influence the temperature fields greatly.
Double-Properties Casting Technology for Superalloy Integral Turbine Wheels
TANG Xin, CAO La-mei, GAI Qi-dong, LI Ai-lan, ZHANG Yong, LIU Fa-xin
2006, 26(3): 93-98.
[Abstract](1217) [PDF 1316KB](325)
Abstract:
The cast process of superalloy double-properties cast integral turbine wheels was introduced.The form method,control means and pour parameters of grain structure of double-properties cast wheels were investigated.At the same time,the selection of double-properties cast wheels alloy material and the effect of heat treatment conditions on mechanical properties were also investigated.The results showed that the overheat temperature of molten metal ΔT and the mould revolution velocity n were 160～290℃ and K+270～K+300 rpm respectively.The directionally solidified columnar grain in airfoil and equiaxed fine grain in hub could be obtained.The heat treatment condition of double-properties cast wheels was 1180℃/2h+1230℃/3h,AC+1100℃/4h,AC+870℃/20h,AC.
Research on Warm Hydroforming of Aluminum Tube
QI Jun, HE Zhu-bin, YUAN Shi-jian
2006, 26(3): 99-102.
[Abstract](1487) [PDF 915KB](411)
Abstract:
The influence of temperature on mechanical properties of 5A02 aluminum tube was investigated first by tensile test.Based on the tensile test results,finite element simulation of tube hydrobulging was carried out to show the formability of 5A02 aluminum tube at elevated temperature.Primary experiment work was also carried out meanwhile.The results of both FEM simulation and hydrobulging experiment showed the same changing tendency of formability of the aluminum tube as the tensile test.The appropriate forming temperature of 5A02 aluminum tube was about 200～230℃.Some possible reasons were given and discussed for the considerable difference between the maximum bulging ratio between FEM simulation result and experimental results.
Vaccum Brazing of a Directionally Solidified Ni3Al-Base Superalloy IC6A
MAO Wei, LI Xiao-hong, YE Lei
2006, 26(3): 103-106.
[Abstract](1461) [PDF 866KB](274)
Abstract:
An experimental investigation on the vaccum brazing of IC6A,a directionally solidified Ni3Al-base superalloy was performed.Three types of cobalt-base filler metals,Co45CrNiWBSi,Co45NiCrWB and N300E were used.The experimental results showed that the three filler metals possessed good brazability on the IC6A base metal,and sound joints were obtained with these filler metals.However,the joints brazed with Co45CrNiWBSi filler metal bearing elements Si and B possessed poor stress-rupture properties,and the ones brazed with N300E and Co45NiCrWB possessed better stress-rupture properties.N300E and Co45NiCrWB contained only B as the melting point depressant.The life under 900℃/160MPa of the joint brazed with the Co45NiCrWB filler metal surpassed 100h.
Effect of Diffusion Treatment on Microstructures and Mechanical Properties of Wide-Gap Brazed Joints of Cast Superalloy K403
LI Da-bin, LIANG Hai, SUN Ji-sheng, PAN Hui, LIU Xiao-fang
2006, 26(3): 107-110.
[Abstract](1543) [PDF 1212KB](364)
Abstract:
The effect of diffusion treatment parameters on microstructures and stress-rupture properties of wide-gap brazed joints of cast superalloy K403 using self-developed brazing filler metal with FGH95 filler powder addition into the gap was studied.The results showed that after post-braze diffusion treatment at 1180℃ for 32h,the chemical composition and microstructure of the brazing seam were uniform,and the matrix of the brazing seam structure consisted of γ solid solution with γ′ phases of 50～53 volume percent uniformly dispersed.A small amount of little blocky or granular carbide and boride distributed along the grain boundary,and the Chinese script boride was eliminated.The stress-rupture strength at 975℃ of the brazed joint was comparatively high.
Gas Tungsten Arc Welding of Ti-24Al-15Nb-1Mo Alloy
LIU Wei-hong, LI Yan, MAO Wei, LI Xiao-hong, CAO Chun-xiao
2006, 26(3): 111-115.
[Abstract](1138) [PDF 952KB](298)
Abstract:
Ti-24Al-15Nb-1Mo alloy was welded by gas tungsten arc(GTA) welding(in argon chamber) with Ti-Al-Nb based alloy,the weld formation,the microstructure and mechanical properties of the joint were investigated.The experimental results show that,under solution treatment condition,this alloy has lower cold-crack susceptibility.As-welded,tensile strength of the joint is 912～927MPa,plastic elongation is 2.5%～3.7% and impact toughness is 4.7J/cm2～10.4J/cm2 at room temperature.Most of the tensile samples failed within the near heat affect zone.
Effect of Postweld Heat Treatment on Microstructure and Properties of Electron Beam Welded TC18 Joint
GUO Shao-qing, GU Wei-hua, YU Huai, YUAN Hong, ZHANG Wang-feng, LI Xiao-hong
2006, 26(3): 116-121.
[Abstract](1401) [PDF 1501KB](358)
Abstract:
In order to improve the mechanical properties of electron beam welded joint in titanium alloy TC18,its tensile and impact properties at room temperature were measured for as welded condition and four kinds of postweld heat treatment.Mean while the microstructure and impact fracture morphology were studied with optical and scanning electron microscope.It is shown that heat treatment can change the shape and size of α phase in initial β grain.With the decrease of L/D ratio for intragranular α,the ductility and impact toughness of welded joint increase while the strength decreases.Double annealing can produce a kind of intragranular structure dominated by α particle and assisted by α plates of appropriate number,then result in better strength,ductility and impact toughness.
Normal Mechanical Property Analysis of P/M Superalloy FGH96 Inertia Friction Welding Joint
HE Sheng-chun, ZHANG Tian-cang, GUO De-lun
2006, 26(3): 122-125.
[Abstract](1497) [PDF 959KB](317)
Abstract:
The secondary P/M powder superalloy FGH96 is the late-model superalloy designed by the method of damage of tolerance limit.FGH96 is the most perfect material of turbine disk,loop-forming element and other components assembly of hot end to meet the challenge of high thrust-weight ratio and high efficiency aircraft engine in 750℃.Combined with grain feature and volume fraction of γ′of FGH96 IFW joint,microhardness and normal tensile property was discussed.The results show that IFW joint exhibits well mechanical property at room temperature.
Effect of Trace Carbon on Properties of Welded Joint of Burn Resistant Titanium Alloy
LI Yan, LI Xiao-fei, DENG Ji-xiong, ZHANG Wen-yang, ZHANG Xue-jun
2006, 26(3): 126-129.
[Abstract](1333) [PDF 828KB](193)
Abstract:
The mechanical properties of EBW joint of Ti-25V-15Cr and Ti-25V-15Cr-XC burn resistant titanium alloys were tested,and the effect of trace carbon(C) in base metal on the properties of welded joint was investigated.The experimental results show that,there are many carbides formed in weld because of trace carbon(C) in base metal.As a result,the tensile stress of joint is improved,while the corresponding ductility is decreased.Particularly,the weld toughness of the base metal containing trace carbon(C) is decreased dramatically,it is only 10 percent of that of the base metal without carbon.
Study on Technology of Low Hydrogen Embrittlement Zn-Ni Alloy Electroplating on Aeronautic High Strength Steel
YU Bo, TANG Zhi-hui, ZHANG Xiao-yun, SONG Li-qiang, LI Bin, LIU Ming-hui
2006, 26(3): 130-134.
[Abstract](1503) [PDF 250KB](541)
Abstract:
The technology of low hydrogen embrittlement Zn-Ni alloy electroplating on aeronautic high strength steel was studied.The technical parameters(such as ratio of Ni/Zn,the current density,temperature and additives) which affect plating performances in acidic chloride eletrolyte was analyzed,obtaining 13wt%~15wt% Ni alloy plate with well corrosion resistance and low hydrogen embrittlement.
Study on Contact Corrosion and Protection between Metal Materials and Basaltic Microfiber Heat-Resistant Materials
LI Bin, LU Feng, ZHANG Xiao-yun, MA Yi-jun, ZHU Yi
2006, 26(3): 135-139.
[Abstract](1422) [PDF 617KB](237)
Abstract:
The contact corrosion in moist environment between metal materials and basaltic microfiber heat-resistant materials used in the aircraft was studied,and the effectiveness of metal surface treatment including chemical conversion treatment,cadmium plating for contact corrosion control was observed and studied.Based on EDS and SEM analysis of metal corrosion surface,the course of contact corrosion between aluminum alloy,structural steel and basaltic microfiber heat-resistant materials were proposed.
Research on Initial Velocity of In-Explosive Cylinder Fragments
MU Ren-de, HE Shi-mei
2006, 26(3): 140-143.
[Abstract](1391) [PDF 686KB](378)
Abstract:
Stresses of the in-explosive cylinder were analyzed,compound criteria for determinating the fracture radius was put forward to calculate the initial velocity of cylinder fragment.High speed photography was adopted to test initial velocity of cylinder fragment of several kinds of materials.The theoretic calculated value of initial velocity was compared with the test value.The result indicated that,for the same kind of material,the theoretic calculated initial velocity value,which adopted compound criteria,matched to test value well.
Application of Multizone Ultrasonic Inspection for Small Defects in P/M Superalloy
LIANG Jing, SHI Yi-wei
2006, 26(3): 144-147.
[Abstract](1476) [PDF 588KB](238)
Abstract:
In the purpose of inspecting small defects in P/M superalloy of large thickness,multizone ultrasonic inspection technique was applied.The sensitivity and signal to noise ratio(S/N) of multizone inspection were measured from a series of flat bottom holes,and C-scan images of a forged P/M superalloy sample were also provided.It was showed that multizone inspection greatly improved the sensitivity and S/N comparing with single zone focused inspection.
Investigation on Indentation Creep by Depth Sensing Indentation
GAO Yang, WEN Sheng-ping, WANG Xiao-hui, PAN Feng
2006, 26(3): 148-151.
[Abstract](4545) [PDF 495KB](1215)
Abstract:
The measurement principles of indentation creep by depth sensing indentation were elucidated,and recent progresses in investigation on indentation creep were also introduced.The creep behavior of metallic materials such as Ta,Ni and Ni-based alloy,BaTiO3 and Ag/Co multilayers were measured by depth sensing indentation.The stress exponents and the corresponding creep mechanism were also analyzed.
Processing and Characterization of Multi-Phase Matrix C/SiC-W Composite
TONG Chang-qing, CHENG Lai-fei, ZHANG Li-tong, XU Yong-dong
2006, 26(3): 152-156.
[Abstract](1487) [PDF 1195KB](293)
Abstract:
A multi-phase matrix C/SiCW composite was prepared by combining chemical vapor infiltration(CVI) technology with solution impregnation method.The phase composition and microstructure of the composite were identified and characterized by XRD and EDS methods,respectively.Reaction mechanism was discussed primarily.The results show that agglomerate tungsten particles are found to infiltrate the pores among the fiber bundles,also among the filaments.The density and open porosity of the C/SiC-W composite are 4.1g/cm3 and 12%,respectively.
Nanostructured Thermal Barrier Coatings by APS and EB-PVD and Their Properties
WANG Ning, ZHAO Wei-xun, WANG Ping, WANG Lu, HE Shi-mei, HUANG Guang-hong, FENG Zi-xiu, WEI Zheng
2006, 26(3): 157-162.
[Abstract](1534) [PDF 990KB](371)
Abstract:
To exploit full potentials of the current widely used yttria-partially-stabilized zirconia(YSZ),nano-sized YSZ powders were developed and used as the ceramic source material.By controlling the deposition processes,novel TBCs with outstanding nanostructures such as nano-sized grains and pores were produced by atmospheric plasma spray(APS) and electron beam physical vapor deposition(EB-PVD),respectively.The incorporated nanostructures in TBCs resulted in substantial increase in hardness,thermal barrier effect and lifetime against thermal cycling.The long-term microstructural stability of nano-coating at elevated temperature was also evaluated.
Preparation of Al2O3(YAG)/LaPO4 Laminated Ceramics Composites
TONG Jian-feng, CHEN Da-ming, LIU Xiao-guang, LI Bao-wei
2006, 26(3): 163-167.
[Abstract](1504) [PDF 1165KB](335)
Abstract:
In the present work,aqueous gelcasting-hot pressing technique to prepare oxide matrix laminated ceramic composites by(using) Al2O3(YAG) as matrix layers and LaPO4 as interfacial layers.The composites with about 110μm matrix layers and 10μm interfacial layers were prepared.The effects of content LaPO4 and procedure parameters of hot-pressing on properties of oxide matrix laminated ceramic composites were investigated.The results show that the bending strength of oxide matrix laminated ceramics decreases a little,while the fracture toughness of as-prepared composites is made much improvement.The maximal apparent fracture toughness of the oxide laminated ceramic composites is 13.52MPa·m1/2,which is three times over matrix composites.The differences of the cracks trend between the oxide matrix laminated ceramic and matrix materials were compared in detail.
Study on Crystalization Behavior Properties of PP/Nano-SiO2 Composite
HUANG Li, LüYa-fei, ZHAN Ren-bo
2006, 26(3): 168-171.
[Abstract](1345) [PDF 193KB](403)
Abstract:
Nano-SiO2 dispersed by ultrasonication technique was modified by silane coupling agent and dispersant agent A,and blended with PP to prepare PP/nano-SiO2 composites by melt-blending process.The influence of nano-SiO2 on the crystallization behavior of PP was studied with differential scanning calorimetry(DSC).Results showed that nano-SiO2 had an nucleating role on the crystallization of PP,resulting in higher crystallization temperature,nucleation rate,and lower the size distribution of crystallite.The research of non-isothermal crystallization kinetics showed that the nucleation mechanism had not significant change at different cooling rate.And the faster of the cooling rate,the higher of the crystallinity at the same crystallization time.
Synthesis and Properties of PMR-Type Polyimide Composites with Improved Flexibility
YANG Hai-xia, LIU Jin-gang, CHEN Jian-sheng, FAN Lin, YANG Shi-yong
2006, 26(3): 172-176.
[Abstract](1486) [PDF 1442KB](460)
Abstract:
A series of novel PMR polyimide(HFPI) matrix resins were synthesized and fully characterization.It was found that the matrix resin solutions were stable for a period of four months at room temperature and showed good adhension on carbon fibers.The short carbon fiberreinforced HFPI composites showed excellent thermal stability and good mechanical properties,with flexural strength and tensile strength of 159.8MPa and 107.3MPa,respectively.And the flexural moduli and tensile moduli were in the range of 5.7-6.1 GPa and 3.0~3.1 GPa,respectively.The good thermal,low moisture uptake(1.7%),and excellent mechanical properties as well as the good processibility demonstrated that the PMR polyimides(HFPI) were candidates as matrix resines of carbon fiber-reinforced composites for advanced materials applications in aerospace industry.
Preliminary Study on Phase Separation Mechanism of PAEK/BMI Blends and Laminated System with Morphology
CHENG Qun-feng, FANG Zheng-ping, YI Xiao-su, XU Ya-hong, LIANG Zi-qing, AN Xue-feng, LI Hong-yun, LIAO Jian-wei
2006, 26(3): 177-182.
[Abstract](1368) [PDF 1240KB](297)
Abstract:
The phase separation mechanism of PAEK/BMI blend was studied by AFM and phase morphology structnre of the PAEK/BMI laminated system was also investigated.The AFM images clearly showed the phase separation mechanism of PAEK/BMI blend,with low content of PAEK,the phase separation progresses according to the Nucleation and Growth mechanism,which leads to the typical phase morphology-sea-island structure.With the content of PAEK increasing,the Spinodal Decomposition mechanism happens and the typical co-continuous phase structure was observed.The content of PAEK further increasing,inverted phase morphology occurred in the blend.The phase separation mechanism observed by AFM was verified by SEM.The impact strength of the blend reached peak value with the 20phr PAEK,approximately increasing 2 times than the neat BMI matrix.The laminated PAEK/BMI system has the similar phase morphology structnre like the blend system.In the region of two matrices,three typical phase structure were observed.This typical phase morphology structnre between PAEK and BMI phase was good for improving the toughness of BMI resin and the composite based on the BMI matrix.Sequentially,the above study makes good foundation for using the typical phase morphology structure to improve the toughness of the composites based on BMI matrix by "ex-situ" concept.
Synthesis and Characterization of High Temperature Transfer Molding Polyimide Resins
CHEN Jian-sheng, ZUO Hong-jun, YANG Hai-xia, LIU Jin-gang, FAN Lin, YANG Shi-yong
2006, 26(3): 183-186.
[Abstract](1581) [PDF 765KB](423)
Abstract:
The synthesis and characterization of phenylethynyl end-capped polyimide oligomers designated PI-1 and PI2 derived from 4-phenylethynylphthalic anhydride(4-PEPA),1,4-bis(4′-amino-2′-trifluoromethylphenoxy)benzene(BTPB),2,3,3′,4′-biphenyltetracarboxcylic anhydride(a-BPDA) and 4-phenylethynyl aniline(p-PDA) are described in this paper,with particular emphasis on melt viscosity stability and thermal properties.PI-1 oligomers show low complex melt viscosity(1Pa·s) at 280℃ and are stable at this temperature,which mean PI-1 oligomers can be processed by resin transfer molding techniques.The cured resins of PI-1 and PI-2 exhibit high glass transition temperatures(400℃ DMA tanδ) and high 5% weight loss temperatures(520℃).
Effect of Redox Curing System on Curing Reaction of Acrylic Adhesive
ZHANG Hong-feng, LI Lei
2006, 26(3): 187-191.
[Abstract](1461) [PDF 216KB](222)
Abstract:
By means of DSC,Thermal analysis of HCB1 adhesive which wasn′t mixed redox curing system and HCB2 adhesive which was mixed redox curing system was accomplished.The curing procedure of HCB1 adhesive and HCB2 adhesive were determined.(According) to Kissinger,Ozawa and Crane methods,the reaction activation energy and kinetic order of curing reaction on HCB1 adhesive and HCB2 adhesive were calculated.Then,Effect of redox curing system on curing reaction of acrylic adhesive was investigated and studied.The experimental results show that the acrylic adhesive decreases curing temperature and the reaction activation energy by(adoption) of redox curing system.
Application of Solid Film Lubricant on Spacecraft Mechanism
SHEN Jie, CHEN Run-zhai, ZHU Chang-lin
2006, 26(3): 192-195.
[Abstract](1443) [PDF 841KB](626)
Abstract:
Two kinds of solid film lubricant was studied to meet the requirements of spacecraft mechanism,One named BJ using in outside spacecraft and the other named GYM-8 using in inside.The solid lubricant and resin system were selected,the compatibility among all components was studied.An optimized formularizstion was obtained,which could meet the lubricant demand of spacecraft mechanism at high temperature,low temperature,vacuum and irradiation environments.Using solid film lubricant in spacecraft has been succeed in the first time.
Study on Wave-Absorbing Properties Advanced Stiffened Grid Structure
JIANG Shi-cai, XING Li-ying, LI Bin-tai, CHEN Xiang-bao
2006, 26(3): 196-198.
[Abstract](1413) [PDF 463KB](403)
Abstract:
The wave-absorbing properties of Advanced Stiffened Grid Structure(AGS)was studied.The research results show that the AGS have the excellent wave-absorbing properties.The optimal radar-absorbing properties were obtained for the radar-absorbing structure composite made from the AGS with circuit analog.It’s reflectivity is no more than-5dB at 8-18GHz.The least reflectivity of the system is 24.4 dB.
New Type of Chromate-Free Anticorrosion Polysulfide Sealant
WU Song-hua, QIN Peng-bo, WANG Jing-he, YI Xiao-su
2006, 26(3): 199-202.
[Abstract](1372) [PDF 778KB](247)
Abstract:
Most used anticorrosion sealants contained dichromate which was soluble ever before.Dichromate is very poisonous and can cause cancers.So it trends to study the chromate-free anticorrosion sealant.We emphasized to study anticorrosion effect of imidazole-(NH4)6Mo7O24 in the polysulfide sealant and primarily researched the anticorrosion mechanism of it.
Study on Heat-Resistant Property of Organic-Silicone Sealant
FAN Zhao-dong, ZHANG Peng, WANG Heng-zhi, CHENG Xiao-yang, WANG Jing-he
2006, 26(3): 203-206.
[Abstract](1378) [PDF 728KB](442)
Abstract:
The heat-resistant property of a room temperature-curable silicone sealant was studied in this paper.The tensile strength and elongation after hot air aging for 50~100h at 350℃ or 200h at 300℃ was determined.The relationship between the heat-resistant property of silicone sealant and the structure of polydiorganosiloxane,fillings,oxidation-resistant,curing ingredient was discussed.The result showed the prepared organic-silicone sealant could withstand 350℃.
Properties of Silicone Rubber at High or Low Temperature
SU Zheng-tao, WANG Jing-he
2006, 26(3): 207-212.
[Abstract](1529) [PDF 1350KB](826)
Abstract:
The article mainly shows the properties of silicone rubber at high or low temperature.The effects of metal oxides Fe2O3,Fe2O3/SnO2,SnO2,CeO2 on the thermal stability of methyl-vinyl silicone rubber(VMQ),methyl-phenyl-vinyl silicone rubber(PVMQ),and trifluoropropyl contained silicone rubber(FVMQ) were studied by heat aging test.Through coefficient of cold-resistance under compression and DMTA,the characters in low temperature of VMQ,PVMQ and FVMQ were also studied.Result shows that metal oxides such as Fe2O3,Fe2O3/SnO2,SnO2 and CeO2 can greatly improve the thermal stability of silicon rubber.The analysis of x-ray photoelectron spectroscopy(XPS) showed that Sn+4 were reduced to Sn0 in silicone rubber during thermal air aging.The thermal stability of silicone rubber could be improved by some metal oxide.The results of DMTA showed that the rubber based on PVMQ,SKTFT-50,SKTFT-25 and the copolymer have excellent cold resistance.
Study on Compatibility of Fluoroether Rubber and Fluorosilicone Rubber
WANG Li, LI Fu-ping, JIANG Hong-gang, WANG Jing-he
2006, 26(3): 213-216.
[Abstract](1452) [PDF 484KB](353)
Abstract:
Fluoroether rubber and fluorosilicone rubber exhibit excellent fluids resistant as well as good behavior both in high and low temperature.The compatibility of fluoroether rubber and fluorosilicone rubber blends has been studied using vulcameter,dynamic mechanical thermal analysis(DMTA)and differential scanning calorimetry(DSC).Results showed that triallyl-isocyanurate(TAIC) had more effects on the vulcanization of fluorosilicone rubber than that of fluoroether rubber and would transfer to fluorosilicone rubber phases from fluoroether rubber phases during mixing,storage and/or vulcanization.It′s hard to get cure compatible and phase compatible blends by ways no matter starting from gums or from compounds.
Manufacture of Thermoplastic Matrix Composite Stiffened Panel Using Flexible Co-woven Prepreg
AN Xue-feng, ZHANG Ming, TANG Bang-ming, YI Xiao-su
2006, 26(3): 217-221.
[Abstract](1439) [PDF 576KB](319)
Abstract:
PEEK matrix composites exhibit great toughness and damage resistance.But the severe processing conditions and poor drapability result in in-efficiency in curved surface forming.This difficulty can be solved by flexible co-woven prepreg technology,facilitating the manufacture of complex curved surface structure with high quality and efficiency.The advantage of this flexible prepreg was demonstrated through the manufacture of stiffened panels with L stiffers and U stiffers,respectively.
Double-Vacuum-Bag Process for Composites
LI Bin-tai, ZHANG Bao-yan, XING Li-ying, CHEN Xiang-bao
2006, 26(3): 222-225.
[Abstract](1437) [PDF 1258KB](568)
Abstract:
Vacuum-bag process is a low-cost method for fabricating composites.A double-vacuum-bag(DB) process was investigated to improve Vacuum-bag process.As evidenced by the C-Scan and optical photomicrographs,low void composite with high mechanical property can be produced through double-vacuum-bag processing technique.So the vacuum-only double-vacuum-bag process can improve quality of composites.
Progress on Self-Healing Silicon Carbide Ceramic Matrix Composites and Its Applications
ZHANG Li-tong, CHENG Lai-fei, XU Yong-dong, LIU Yong-sheng, ZENG Qing-feng, DONG Ning, LUAN Xin-gang
2006, 26(3): 226-232.
[Abstract](4491) [PDF 2055KB](1020)
Abstract:
Continuous fiber reinforced silicon carbide ceramic matrix composites were developing towards possessing self-healing properties for the need of high thrust mass ratio aerospace-engine working in thermal oxidizing environment.The microstructure and properties of a self-healing silicon carbide matrix composite were introduced.The mechanism of toughness and stiffness of the composite and the self-healing behaviors were commented.The application progress of self-healing silicon carbide component was summarized.Manufacturing method and technique feature were reviewed.Multi-component and multi-layer microstructure was the key point for this composite possessing self-healing and toughing properties,and oxidation resistant system which exhausted O2 and sealed crack in each layer.This self-healing silicon carbide matrix composite coule not only meet the requirements of for aerospace-engine service but decreased weight remarkably,increased thrust-weight ratio in return.
Research on Basic Theories of Ti40 Burn Resistant Titanium Alloy
ZHAO Yong-qing, ZHOU Lian, ZHOU Yi-gang, QüHeng-lei, WU Huan, YANG Hai-ying
2006, 26(3): 233-237.
[Abstract](1539) [PDF 1163KB](287)
Abstract:
Burn resistant titanium alloy has important using promising.Ti40 alloy is a new type burn resistant titanium alloy developed by China.The progress on basic theories of Ti40 alloy,such as deformation mechanism,oxidation mechanism,burn resistant mechanism and so on,was reviewed.
Progress of Advanced Near Net-Shape Investment Casting Technology of Superalloys
CAO La-mei, TANG Xing, ZHANG Yong, XUE Ming, LI Ai-lan, GAI Qi-dong, LIU Fa-xin
2006, 26(3): 238-243.
[Abstract](4501) [PDF 1313KB](992)
Abstract:
The recent development of near net-shape investment casting technology for superalloys was introduced.The researching results of investment casting technology for superalloy turbine blades/vanes,integral turbine wheels,nozzle assembly and casings of aero engine in BIAM were mainly introduced.Meanwhile the researching scopes in the future was discussed.
Development and Application of P/M Superalloy
ZOU Jin-wen, WANG Wu-xiang
2006, 26(3): 244-250.
[Abstract](4765) [PDF 1317KB](1112)
Abstract:
P/M superalloy becomes excellent material for fabricating turbine discs used for advanced aviation enging due to its special structure and properties.To advance the applicable property and security of aviation enging,the material from melting original alloy to engineering application of turbine disc was studied,and remarkable results in aspect of so many key technologies were gained due to the result of the foundation of fabricating technique for turbine disc and the establishment of process and testing documents.Numerical simulation is widely used to fabricate P/M turbine disc for the purpose of shortening studying period and optimizing processes,and the preparatory experimental results were achieved.
Development of a New Creep Resistant Al-Cu-Mg-Ag Type Alloy
ZHANG Kun, DAI Sheng-long, YANG Shou-jie, HUANG Min, YAN Ming-gao
2006, 26(3): 251-257.
[Abstract](1756) [PDF 317KB](551)
Abstract:
Development of a new creep resistant Al-Cu-Mg-Ag type alloy in recent years were presented for their composition design,microstructural evolution and the effect of heat treatments on properties.Compared to the other candidate materials for the next generation supersonic aircrafts,Al-Cu-Mg-Ag alloys are creep resistant and most costly,and then become a most promising medium strength aluminum alloy on high temperatures.
Spray Formed Superalloys and Their Fabrication Technologies
ZHANG Guo-qing, LI Zhou, TIAN Shi-fan, YAN Ming-gao
2006, 26(3): 258-264.
[Abstract](1434) [PDF 1112KB](544)
Abstract:
As a novel technology to directly produce preforms or semi-products of metal materials using rapid solidification technique,spray forming has been rapidly developed to process high-alloyed and hard-to-process superalloys in recent years.The status of the spray forming of high temperature structural materials was briefly reviewed,including the development of the unique spray forming plants,spray atomization-deposition process and their applications.The spray forming route for compositionally complex high-strength nickel-base superalloy disks was also compared with conventional ingot metallurgy and powder metallurgy both metallurgically and economically.Sound preforms of wrought,powder metallurgy and cast superalloys could be achieved by optimising spray atomization and deposition variables using either nitrogen or argon as atomisation gas.The high-quality preforms exhibited highdensity,refined grains,homogenous microstructures,segregation-free macrostructure,low gas contents,improved workability and enhanced mechanical properties.
Research and Development of AerMet100 Steel
LI Zhi, ZHAO Zhen-ye
2006, 26(3): 265-270.
[Abstract](1578) [PDF 1263KB](423)
Abstract:
Since the publication of U.S. Patent and AMS specifications of AerMet100 steel,A lot of changes have taken place about the criteria stipulated in these technical documents.Considering these changes,combining the achievements gained in our researches engaged in the BIAM and consulting the technical papers published abroad,we drew out some ideas about improving the fracture toughness of AerMet100 steel.Continuing increasing the purification and cleanliness would be one of the most important measures;adding multiple rare earth elements as trace constituents would change the composition and size of the inclusions as well as improve the distribution of these inclusions,so the inversion effect of the inclusions on fracture toughness would be reduced.The stable reverted austenite formed during heat treatment would be positive to the fracture toughness.
Development of Corrosion and Protection for Aeronautical Materials in China
CAI Jian-ping, LU Feng, WU Xiao-mei
2006, 26(3): 271-275.
[Abstract](1554) [PDF 885KB](733)
Abstract:
The corrosion and protection for aeronautical materials in China is reviewed.The techniques and research in natural environmental test,indoor accelerated tests,corrosion mechanics and tests,high temperature protective caotings,surface treatment and protective techniques are introduced.The development trend and application prospect of corrosion and protection are proposed.
Welding Technologies of Advanced Aeronautical Materials and Complex-Shaped Structural Components
LI Xiao-hong, MAO Wei, XIONG Hua-ping
2006, 26(3): 276-282.
[Abstract](1467) [PDF 1666KB](462)
Abstract:
The main results and progress of the research on welding technologies of advanced aeronautical materials and complex-shaped structural components in the past 5 years in Beijing Institute of Aeronautical Materials(BIAM) are summarized in this paper.Not only some valuable pioneered research results but also some joining techniques which have acquired practical application are presented.
Progress on Electrically Conductive Silicone Rubber
GENG Xin-ling, LIU Jun, REN Yu-zhu, SU Zhengtao, WANG Jing-he
2006, 26(3): 283-288.
[Abstract](5022) [PDF 862KB](1739)
Abstract:
This paper introduced the two main electrica1 conduction mechanisms of the silicone conductive rubber,which are conductive pathway theory and quantum mechanics tunne1ing effect theory.The progress of electrical1y conductive fillers is mentioned,and the factors affecting the conductive properties of silicone rubber are discussed based on temperature,pressure,machining technics and so on.In addition,the applications and prospect of the conductive silicone rubber are briefly viewed.
Effect of Shot-Peening on Surface Roughness of NiCoCrAlY Coating on Ni3Al Base Alloy IC6
SONG Jin-xia, HAN Ya-fang, LIU Qing-quan, GONG Sheng-kai, LI Shu-suo, ZHAO Song
2006, 26(3): 289-290.
[Abstract](1316) [PDF 287KB](416)
Abstract:
The effect of shot-peening on the surface roughness of NiCoCrAlY coating on Ni3Al base alloy IC6 was investigated. The results indicated that shot-peening could obviously decrease the roughness of NiCoCrAlY coating to smaller than 1.6μm,and also increased the density of the coating,as shot-peening was carried out after the vacuum diffusion heat-treatment of the coating,the pressure was 0.4MPa and lasting time was 4min.Moreover,the residual compressive stress did not result in the recrystallization of IC6 alloy.Therefore,it was feasible to decreasing the surface roughness of NiCoCrAlY coating by shot-peening.
Study of Long-Time Structural Stability of In706 Alloy
YAN Ji-zhang
2006, 26(3): 291-292.
[Abstract](1343) [PDF 621KB](352)
Abstract:
After the long-time age treatment of In706 alloy at the 650℃ for 500h or 1000h,the microstructure and mechanical properties of alloy were measured.The test reaults show that these alloy possesses good stability of microstructure,high tress rupture life and ductility.Therefore In706 alloy can be used rotational component of aeroengine,such us disk,shaft.
Effects of HIP Temperature on Microstructure of FGH96 Superalloy
WANG Xu-qing, LUO Xue-jun, ZOU Jin-wen
2006, 26(3): 293-294.
[Abstract](1342) [PDF 761KB](440)
Abstract:
The temperature of hot isostatic pressing(HIP) is a very important parameter for P/M superalloy.The effects of HIP temperature on microstructure of FGH96 superalloy were studied.The results showed that remained dendrites were removed by higher HIP temperature.Recrystallization was promoted and grain size was increased with increasing temperature of HIP.Original γ′ were dissolved effectively and cooling γ′ grew with higher HIP temperature.
Homogenization Treatment of Superalloy IN783
LI Zheng-dong, ZHANG Guo-qing, ZHAO Yu-xin
2006, 26(3): 295-296.
[Abstract](1352) [PDF 326KB](350)
Abstract:
The segregative phases and it’s solution temperature in alloy IN783 were investigated.A optimum homogenization treatment system was proposed based on the study of microstructures and the segregative phases in the specimen after a number of heat treatments.
Study on Corrosion Behavior of 2D12 Aluminum Alloy
SUN Zhi-hua, LIU Ming-hui, ZHANG Xiao-yun, GAO Jian, LU Feng, DAI Li-jin
2006, 26(3): 297-298.
[Abstract](1477) [PDF 548KB](325)
Abstract:
The corrosion behavior of 2D12 alloy was evaluated including intergranular corrosion,exfoliation and stress corrosion cracking.The results show that there are intergranular corrosion and exfoliation tendency for 2D12 alloy T4 temper.It is also shown that the KICC of S-L and S-T orientation are 22.6 and 27.1 MPa·m1/2, respectively,that is the same as C-ring result,and the fractographies of T4 temper reveal intergranular fracture.
Experimental Study on Flexible Bending of Aluminum Profiles with Hyper-Elastic Pad
HE Zhu-bin, TANG Ze-jun, ZHANG Qi, WANG Zhong-ren
2006, 26(3): 299-300.
[Abstract](1338) [PDF 384KB](311)
Abstract:
Experimental work using two typical aluminum profiles with different sections was carried out to investigate the influence of main process parameters on the bending process.Results show that the shape and relative thickness of section,section modulus in bending are the main factors that determine the bending properties of the profiles.Roller stroke,properties of hyper-elastic pad and constraints on profiles are key factors that determine the bending radius and cross-section deformation of bent profiles.Typical failures or quality problems met in experiments were analyzed meanwhile.
Primary Study of Effect of Rare Earth on Microstructure and Mechanical Properties of Super Pure Ultra High Strength 23CoNi Steel
WANG Jun-li, LI Zhi, JIN Jian-jun, ZHANG Ji-zhong, SU Bin, GU Li-xin
2006, 26(3): 301-302.
[Abstract](1415) [PDF 623KB](277)
Abstract:
The addition of rare earth elements into 23CoNi steel caused δ5 and ψ improved,and σb and aku increased slightly,but the indistinctive effect on KIC and σ0.2.As a result,the addition of rare earth could form rare earth compounds which contain S and Al.The other finding of the study was that rare earth elements blocked the grain growing up and refined martensitic laths.
Experimental Study of Contact Fatigue for Deep Nitrided Steel
JIANG Zhi-hua, LI Zhi, TONG Xiao-jun, LI Zhiming
2006, 26(3): 303-304.
[Abstract](1443) [PDF 423KB](288)
Abstract:
The contact fatigue experiment study was carried out for VIM+VAR 32Cr3MoVE steel by deep nitriding.The results showed that failure morphology was of typical contact fatigue characteristics,and two modes of fatigue crack formation worked.The steel by deep nitriding possessed excellent microhardness gradient and favorable distribution of residual compressive stresses,and the contact fatigue life of nitrided steel under the given load showed a great improvement in relation to carburized 18CrNi4A steel.
Investigation on Coarseness and Evolvement of γ′ CcPhase of GH742 Alloy
XIE Yong-jun, LIANG Xue-feng, LI Wei, ZHAO Yu-xin, MIAO Hong-bo
2006, 26(3): 305-306.
[Abstract](1417) [PDF 227KB](218)
Abstract:
The effect of special treamtent afterhom ogenization on γ′ phase of GH 742 ingot and the principle of precipitating-dissolving of γ′ phase w as investigated.The results show that the size of coarse γ′ phase is 4~8 tmies bigger than that of γ′ phase of ingot and the soluble temperature of γ′ phase by special treamtent is about 1100℃.
Effect of Sample Positions on Creep Properties of FGH95 Superalloy Disk
LUO Xue-jun, WANG Xu-qing, HU He, ZOU Jinwen, WANG Wu-xiang
2006, 26(3): 307-308.
[Abstract](1305) [PDF 286KB](197)
Abstract:
The effect of sampling position on the creep properties at 593℃ and 1034MPa of FGH95 powder metallurgy superalloy with creep test methods by grading loading was investigated.The results indicate that creep properties of different sampling positions relate to the cool rate of that point.The slower cooling rate,the higher plastic strain during loading and the faster creep rates.
Study on Tempered Microstructure and Hardness of 9Cr13Ni6Co5Be Stainless Steel
GU Li-xin, JIN Jian-jun, GU Bao-zhu
2006, 26(3): 309-310.
[Abstract](1332) [PDF 478KB](311)
Abstract:
The microstructure and hardness after tempering of 9Cr13Ni6Co5Be steel was studied.It shows that the highest hardness gains on tempering at about 470℃.The formation of finely dispersed Be2Fe phase which coheres with the matrix is responsible to the highest hardness of steel.The orientation relationship between Be2Fe and martensite is(1—10)M//(2—10)Be2Fe,M//Be2Fe.And the steel possesses higher hardness than common tool steel at 500℃.
Effect of Heat Treatment on Microstructure of K4169 Superalloy
LI Ai-lan, TANG Xin, GAI Qi-dong, CAO La-mei, LIU Fa-xin
2006, 26(3): 311-312.
[Abstract](1418) [PDF 369KB](441)
Abstract:
The effect of heat treatment on microstructures of K4169 alloy was investigated by optical metallography.The results showed that the volume fraction of Laves phase reduced and a plate-like phase formed in a region close to the Laves phase after 1095℃ homogenization+955℃ solution+720℃ aging.Neither δ and Laves phase nor microshrinkage was found after the 1120℃ HIP + heat treatment sample.The results of the investigation show that the HIP + heat treatment process is a good process.
Effect of Microstructure on Damage Tolerance Properties and SEM in-situ Observation for Titanium Alloy
ZHANG Wang-feng, LI Xing-wu, MA Ji-min, CAO Chun-xiao, ZHU Zhi-shou
2006, 26(3): 313-314.
[Abstract](1415) [PDF 259KB](283)
Abstract:
The crack tip morphology,fatigue crack propagation rate and propagation path were investigated for TA15 titanium by SEM tension and SEM fatigue,and they were compared with macro mechanical properties.The results show that damage tolerance properties of lamellar are better than global and bi-model structure,because of crack tip blunting and crack branching or zig-zag path in the lamellar structure,i.e.fracture toughness is highest and fatigue crack propagation rate is the lowest in the lamellar structure.
Fabrication of FeSiB Fiber by Rapid-Solidifying Technique and Its Property
GUO Wan-lin, LI Tian-wen, HUAI Jun-feng
2006, 26(3): 315-316.
[Abstract](1412) [PDF 141KB](187)
Abstract:
Rapid-solidifying technique, as a special materials processing method,is widely used in fabrication and processing of many special function materials,such as,noncrystalline braze welding materials thin strips,magnetic materials thin strips,absorbing materials,masking materials thin strip and fibers.Rapid-solidifying materials have both special functional properties and particular mechanical properties,due to its special structures and products forms.Conventional FeSiB magnetic material was investigated,and continuous fiber was prepared by rapid-solidifying method.Mechanical properties of the rapid-solidifying fiber were measured and its application prospects in fields was forecasted.
Microstructure and Bonding Mechanism of TiAl/42CrMo Steel Joints Using Ti-15Cu-15Ni Filler Metal
CHEN Bo, XIONG Hua-ping, MAO Wei, CHENG Yao-yong, YE Lei, WU Xin
2006, 26(3): 317-318.
[Abstract](1409) [PDF 386KB](270)
Abstract:
Ti-15Cu-15Ni was chosen as filler metal for TiAl/42CrMo steel vaccum brazing.The Microstructure and composition distribution of TiAl/42CrMo steel were examined by SEM and EDS.The results showed that the transitional interaction layer was formed at the interface close to TiAl and 42CrMo steel because of interdiffusion and interaction between the filler metal and the base metals.Ti-Al,Ti-Cu(Ni) and Ti-Fe were formed in TiAl/42CrMo steel joint.The bonding mechanism was discussed.
Bonding of IC10 Alloy with Different Interlayer Alloys
YE Lei, LI Xiao-hong, MAO Wei, CHENG Yao-yong, XIE Yong-hui, CHEN Bo
2006, 26(3): 319-320.
[Abstract](1485) [PDF 285KB](217)
Abstract:
The effect of B and Zr as the melting point depressants on the melting temperature range and the bonding behaviors of IC10 alloy with the interlayer alloys were studied.The results showed that with long holding time,the bonding of IC10 with the interlayer alloy containing B was an isothermal solidification process,but for element Zr,it was only a brazing process.
Mechanical Properties of TIG Welded Joint of New Burning-Resistance Ti40 Alloy
ZHANG Wen-yang, LI Yan, LI Xiao-fei, DENG Jixiong
2006, 26(3): 321-322.
[Abstract](1285) [PDF 100KB](262)
Abstract:
Ti40 alloy welding property was studied and its welding texture was analyzed by using metallography and SEM methods.The result showed that Ti40 joint had good room-temperature and high-temperature property,but had lower toughness.Heat treatment after welding could improve microstructure.After 500℃×100h exposure,α precipitation with short bar or ball shaped was found.Crystal boundary was coarsened with α phase.
Investigation on Mechanical Properties and Microstructure of TC18 Titanium Alloy Welded Joints Made by New Developed Wire
GU Wei-hua, GUO Shao-qing
2006, 26(3): 323-324.
[Abstract](1375) [PDF 643KB](362)
Abstract:
The feasibility of using a new developed wire to weld TC18 titanium alloy was discussed.The mechanical properties and microstructure of the joints joined by the new developed filler metal and TC18 filler metal were compared,the results showed that only the strength of the joint joined by TC18 filler metal was satisfied,while the comprehensive mechanical properties of the joint joined by the developed filler wire were ideal.
Joint Structure of SiC Fiber Reiforced Titanium Matrix COompound by Transient Liquid Phase(TLP) Diffusion Bonding
ZHANG-Lei, HOU Jin-bao
2006, 26(3): 325-326.
[Abstract](1366) [PDF 291KB](206)
Abstract:
Based on SiCf/TC4 titanium matrix compound,the Transient Liquid Phase(TLP) diffusion bonding test was carried out and the joint microstructure was investigated.The results indicated that an excellent joining of Titanium matrix compound,which is similar to the parent material,can be obtained using home-made composite interlayer of SiC fiber + TiZrCuNi alloy,which leads to a compact interfacial microstructure of fiber/metal through diffusing.
Study on High-Performance Brazing Technology of K403 Superalloy
ZHANG Sheng, HOU Jin-bao, GUO De-lun, ZHANG Lei
2006, 26(3): 327-328.
[Abstract](1405) [PDF 356KB](299)
Abstract:
A new Ni-based filler material 3P1 was developed for K403 superalloy to improve the high temperature strength and resistance to oxidation of brazing joints.The microstructure and bonding mechanism of the joints were analyzed and high temperature mechanical properties were tested.The experiment results show that a defect free microstructure,similar to the base material,could be obtained by using 3P1 filler material,brazed at 1230℃ for 10min with following diffusion heat treatment(1160℃,4h).At 1000℃,high temperature tensile strength of joints reaches 90% of the base material,and 100h creep strength could be higher than 70% of the base material.
Transient Liquid Phase(TLP)Diffusion Bonding of Ni3Al Alloy
HOU Jin-bao, WEI You-hui, ZHANG Lei
2006, 26(3): 329-330.
[Abstract](1393) [PDF 98KB](374)
Abstract:
The properties of the joint and the change of the TLP joint properties of Ni3Al alloy IC10 after long time employment are all been investigated in this paper.The results show that the properties of the TLP joint have become the same as that of the base material with further diffusion of atoms during the employment under high temperature.
Mechanical Properties Study on Superalloy GH150 for Blades
MIAO Hong-bo, ZHAI Ai-qun, ZHAO Yu-xin, LIANG Xue-feng, ZHANG Shao-wei, XIE Yong-jun
2006, 26(3): 331-332.
[Abstract](1380) [PDF 117KB](206)
Abstract:
Tensile properties,stress rupture properties,creep properties and fatigue properties of alloy GH150 have been studied under service conditions for the high-pressure compressor blades.The results of the tensile tests show that both the tensile strength and the plastic properties keep stable from room-temperature to 600℃ and fall down obviously at 750℃.The creep rupture strength at 600℃ and 650℃,the limitation values of the axis tensile fatigue(under 107 cycle) and the limitation values of the rotating bending fatigue(under 107 cycle) obtained from this experiment show that alloy GH150 is with good combination properties.
Effect of Precursors on the Sintering Behavior and Microstructure of Sr0.7Ba0.3Nb2O6 Ceramics by Solid Solution Techniques
WANG Wei, ZHANG Jie, JIAO Gang-cheng, FAN Huiqing
2006, 26(3): 333-334.
[Abstract](1362) [PDF 430KB](247)
Abstract:
Sr0.7Ba0.3Nb2O6 ceramics(SBN70) were prepared by using conventional sintering techniques from nitrate precursor(NSBN70) and carbonate precursor(CSBN70).The sintering behavior and structures evolution of NSBN70 was characterized of X-ray diffraction(XRD) and scanning electron microscopy(SEM).The effect of precursors on the sintering behaviors and structure evolutions was studied.SBN70 from nitrate precursors is produced at 1400℃ for 4h or 1375℃ for 6h.SBN70 from nitrate precursors showed a duplex microstructure.Abnormal grain growth occurs more easily than SBN70 from carbonate precursors.
Analysis on structure and Healing Mechanism of Self-Healing Polymer Composites
FANG Zheng-ping, YANG Hai-tang, XU Li-hua, GU Ai-juan, TONG Li-fang, XU Zhong-bing
2006, 26(3): 335-336.
[Abstract](1399) [PDF 361KB](269)
Abstract:
The classification,composition and healing mechanism of self-healing polymeric composite were introduced and the implant self-healing system,as an example of passive mode,is set forth in detail.A new passive mode self-healing design is proposed based on the analysis of the disadvantages of the present systems.
Preparation of Nano-Porous Zirconia Aerogel
ZHANG He-xin, HE Xiao-dong, LI Yao, HONG Chang-qing
2006, 26(3): 337-338.
[Abstract](1385) [PDF 323KB](153)
Abstract:
Nano-porous ZrO2 aerogels were prepared with zirconyl nitrate dihydrate(ZrO(NO3)2·5H2O) by heating hydro-thermal method subseqently supercritical drying technique.The prepared aerogels are performed by SEM and BET to characterize and analyze the morphology and pores characteric of ZrO2 aerogels.The results showed that: The areogels are the typical of nano pores in the interval between 5Dp60 nm;the specific surface areas reach 916.5m2/g;There is a homogeneous pore distribution in aerogel.Morever the gel process was also discussed in this research.
Study on Reaction Kinetics of Epoxy Cured by Electron Beam
BAO Jian-wen, LI Ye, ZHONG Xiang-yu, CHEN Xiang-bao
2006, 26(3): 339-340.
[Abstract](1046) [PDF 304KB](125)
Abstract:
The reaction kinetics of EB curing epoxy initiated by diaryiodinium was investigated.Before the resin was gelled,its reaction rate was controlled by the concentration of epoxide group and the concentration of the proton acid(HX) generated by the decomposition of initiator.In the initial period of the reaction,the concentration of the HX increased with the reaction time,the reaction rate was controlled by HX mainly.In the second period,the concentrations of HX and epoxide group co-controlled the reaction rate.In the third period,the initiator was decomposed completely,the rate was controlled by epoxide group,and it is first order reaction.
Fabrication and Dielectric Property of Polymer-Matrix Composites Containing AlN Particles for Electronic Substrates
ZHANG Jie, WANG Wei, ZENG Xian-hua, SHI Yun-ze, FAN Hui-qing
2006, 26(3): 341-342.
[Abstract](1498) [PDF 109KB](99)
Abstract:
The fabrication processing,dielectric properties and thermal properties of polymer-matrix composites containing AlN particles for electronic substrates and microelectronic packaging applications are investigated.The epoxy resin is used as the polymer matrix in the composites.The properties of the composites are measured in the range of AlN contents changing from 0.00 to 30vol%.With increasing the content of AlN particles,thermal conducting of composites is improved,while the composites still keep the relatively low dielectric constant and dielectric loss.
Study on Stitched Carbon Fabric Satin Weave Composites
GUO Yang, GONG Shao-bo, XING Fu-jun
2006, 26(3): 343-344.
[Abstract](1326) [PDF 276KB](175)
Abstract:
Layers of dry carbon fabric satin weave G803-T300-40B were stacked and stitched through the thickness with high strength glass threads.RFI of perform with modified epoxy resin followed by autoclave curing process.Viscosity of the RFI resin film as a function of curing temperature and time were tested respectively.The mechanical properties of stitched and unstitched composite laminates were evaluated.
Solid Film Lubricant Used in Aircraft
LI Feng-lan, CHEN Run-zhai, ZHANG Yan
2006, 26(3): 345-346.
[Abstract](1419) [PDF 104KB](83)
Abstract:
Two kinds of solid film lubricant,HR-7201 and HR-7101,were prepared to fit new aircraft.Solid film lubricant was made by home-made materials.Different materials including resin,solid lubricant and mixed solvent were selected,the compatibility among all components was studied.The prepared solid film lubricant has such properties: low friction coefficient,heat and cold resistance,fluids resistance,etc.HR-7201 can be used where temperature range from -60℃ to +300℃,and then HR-7101 can be used at temperature range form -60℃ to +200℃,intermittent exposure to 250℃ is acceptable.The solid film lubricants has passed representative component part test and long time trial run and has used in aircraft.
Study on Evaluation of Set up of Properties and Level of Property of Aronautical Sealant
CAO Shou-de, HUANG mei-xing
2006, 26(3): 347-348.
[Abstract](1345) [PDF 92KB](90)
Abstract:
Controversial factors and idea in process of set up properties and level of properties of aronautical sealants were inquired and studied.For example,user of sealants put forward self-contradictory technique requirements and undue properties level.Standards of sealants give out erroneous information.How to correctly set up properties,take suitability of sealants on sealing handicraft into account,and accept advanced technique etc.that were studied.
Discussion on Manufacturing Process of Unsymmetric Composite Laminates
LI Min, ZHANG Bao-yan
2006, 26(3): 349-350.
[Abstract](1196) [PDF 276KB](117)
Abstract:
Using unsymmetric composite laminates are benefit to reducing the structure weight of some aircrafts such as helicopter.In this paper,we aim at the control methods of the warpage of the unsymmetrical composite laminates.The method used in our study included adjusting the curing parameters and using the anti-warpage mould.The results of the experiment indicate that reducing curing temperature can reduce the warpage.Using the anti-warpage mould is an effective method of controlling the warpage,but it could cause the distortion,and the mould design needs further investigation.
Effects of Prepolymerization Process on Dielectric Performance of Bismaleimide-Cyanate Ester Resin Systems
ZHONG Xiang-yu, HONG Yi-qiang, BAO Jian-wen, CHEN Xiang-bao
2006, 26(3): 351-352.
[Abstract](1367) [PDF 104KB](155)
Abstract:
The effects of prepolymerization and postcure temperature on the dielectric performance of bismaleimide-cyanate ester copolymer are investigated in this article.The study shows the prepolymerization of cyanate ester has influence on dielectric performance.The prepolymerization of bismaleimide can increase dielectric loss dissipation.
Study on Thickness of Thermal Barrier Coatings with Eddy-Current Testing Technology
ZHOU Jun-hua, XU Ke-bei, GE Zi-liang
2006, 26(3): 353-354.
[Abstract](1474) [PDF 340KB](230)
Abstract:
Using the technology of eddy-current testing,the electromagnetic characteristic of each coating on the thermal barrier coatings(TBCs) is confirmed.Basing on the structure and the electromagnetic characteristic of TBCs,the theory model of TBCs is built,analogy experiment is performed,and then the factor influencing the measurement of thickness is analyzed.TBCs sample of different structure is made,measurement experiment is conducted,a satisfactory result is acquired,and the requirement of calibration sample is gained,which is used in measuring the thickness of TBCs with eddy-current testing method.
Ultrasonic Characterization of Porosity in Fiber-Reinforced Composites
HE Fang-cheng, SHI Yi-wei
2006, 26(3): 355-356.
[Abstract](1278) [PDF 393KB](144)
Abstract:
The principle of ultrasonic attenuation measurement is introduced.Ultrasonic C-csan imaging characterization of porosity in fiber-reinforced composites was used to evaluate the mechanical properties of the materials.The relationships of ultrasonic attenuation,the void content and mechanical properties were described associating the destructive analyzing of the samples.A ultrasonic characterization method was explored in the field of evaluating the porosity and mechanical properties in fiber-reinforced composites.
Analysis of Characteristic of Ultrasonic C-Scanning Testing for Braze Quality of Multi-Layer Welding Line
WANG Zheng, SHI Yi-wei
2006, 26(3): 357-358.
[Abstract](1314) [PDF 350KB](75)
Abstract:
The superposition of ultrasonic wave in the ultrasonic C-scanning testing for braze quality of multi-layer welding line is discussed minutely in this article.The simulation for the ultrasonic wave by different path is made.The result of experiment testifies the accuracy of this research.
Application of DC Current Method for Crack Length Measurement in High Temperature
WANG Liang, DING Chuan-fu
2006, 26(3): 359-360.
[Abstract](1311) [PDF 94KB](330)
Abstract:
A measurement method is described in this paper for crack length.Fatigue crack growths under constant amplify and crack length of threshold behavior base on this method in the high temperature.According to automation level of measurement crack length is improved.

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