航空材料学报

Hot Deformation Behavior and Microstructure Evolution of Sintered TC4 Alloy Using Hydrogenated Powder

TIAN Ya-qiang, HOU Hong-liang, REN Xue-ping

2011, 31(1): 1-6.

[Abstract](1280) [PDF 1114KB](178)

Abstract:
The hot deformation behavior and microstructure evolution of TC4 alloy by die forming and sintering using hydrogenated powder with hydrogen content of 0.42% were studied in the temperature range 850~1000℃ and strain rate range 0.001~0.1 s-1 by hot compression tests.Characteristics of stress strain curves of the alloy deformed with the test parameters were analyzed.Kinetics analyses indicate that the stress exponent and deforming activation energy were 3.97 and 507.35 kJmol-1 respectively,which indicate that dynamic recrystallization occurred.Microstructure observation indicates that the grains was elongated along metal flowed with deformation in region,the same microstructure change of phase as region besides recrystallization aggravated in + region deformation,it take place recrystallization of phase original duplex structure which the mass fraction of primary phase content showed a decreasing trend.

Effect of Carbon Content on Microstructure and Mechanical Properties of Type 15-5PH Precipitation Hardened Stainless Steel

LIU Zhen-bao, LIANG Jian-xiong, YANG Zhi-yong, GU Li-xin, ZHANG Xiu-li, SUN Chang-liang

2011, 31(1): 7-12.

[Abstract](1265) [PDF 972KB](331)

Abstract:
There trial heats of 15-5PH stainless steel in different carbon contents melting by vacuum induction furnace were secured,and by using thermal simulation,best rolling temperature range of 900~1100℃ has been gained.The effect of carbon content on transformation temperature and mechanical properties of the steel was studied,and the microstructure of aging were observed.The results showed that,the transformation temperature decreasing with the increasing of carbon content,after aging treatment,the strength of #1 steel was higher than the strength of #2 and #3 steel,and #1 steel also has better ductile plastic;Compare to #1 steel,the formation speed of reverted austenite is faster and amount is more in #2 and #3 steel with aging temperature increasing,this is main reason of the lower strength of #2 and #3 steel.After aging,the microstructure of 15-5PH steel is lath martensite and a few reverted austenite,with large amount of fine precipitates rich in copper,the Cu-rich precipitates are major enhancement patterns of the steel.So we recommend the chemical composition and technical parameters of #1 steel as engineering goal of 15-5PH steel,and provides some data for reference in the industrial production of the steel in the near future.

Creep Behaviors and Influencing Factors of Hot Rolling Ti-6Al-4V Alloy

TIAN Su-gui, BAO Xian-yu, YU Hui-chen, LIU Yang, ZHAO Zhong-gang, CHEN Li-qing, LIU Xiang-hua

2011, 31(1): 13-19.

[Abstract](1201) [PDF 2095KB](191)

Abstract:
By means of creep curves measurement and microstructure observation,the influence of three preparing technics(hot rolling,long-term aging and solution aging) on the microstructure and creep properties of Ti-6Al-4V alloy is investigated.Results show that,under the applied stress of 575 MPa at 400℃,the hot rolled Ti-6Al-4V alloy displays a shorter creep lifetime about 70h,but after long-term aging and solution + aging,the creep lifetimes of the alloy at the same testing conditions are prolonged to 230h and 548h,respectively.Microstructure of the hot rolled alloy consists of band-like α phase and network αphase.After long-term aging,significant amount of β particles are precipitated in the α phase.After solution + aging,the microstructure of the alloy consists of the network basket structure with high volume fraction and the equiaxial α phase,which is the main reason of having longer creep lifetimes.During creep,the deformation mechanism of the hot rolled alloy is the dislocation slipping activated in the α phase,while the deformation mechanism of the solution + aging alloy is the a+c dislocations of the wavilness activated on the pyramidal planes.As creep goes on,more dislocations in the α phase are concentrated and cause the dynamic recrystallization,which refines the grain size of the alloy.It is the synthetical effect of the network basket structure and the thinner α phase that make the solution + aging alloy have longer creep lifetime and better plasticity.

Dynamic Recrystallization and Grain Refining of Superalloy FGH4096

XIE Xing-hua, YAO Ze-kun, NING Yong-quan, GUO Hong-zhen, TAO Yu, ZHANG Yi-wen

2011, 31(1): 20-24.

[Abstract](1318) [PDF 1363KB](238)

Abstract:
Isothermal compression of HIPed(Hot Isostatic Pressed) FGH4096 superalloy in the temperature range 1080~1140℃ and strain rate range 0.02~1s-1 with deformation from 15% to 50% have been conducted on Gleeble-1500D simulator.Recrystallization nucleation and microstructure evolution during the hot deformation have been revealed by TEM(transmission electron microscopy) and MO(metallographic observation).When compressed with the deformation of 35% or blow,a not fully recrystallized microstructure called "Link" microstructure received.Fully recrystallized microstructure obtained when the deformation reached 50%,grain size of which grows as the temperature rise and strain rate decrease.Primary recrystallization nucleation sites could be summarized as follows: PPB(Previous Particle Boundaries),grain boundaries of the recrystallized grain and twin sourse.A fine structure with average grain size of 4μm obtained by the effect of multiaxial hot deformation as a result.

Microstructural Evolution of CP-Ti Processed by ECAP at Room Temperature Using 120° Die

YANG Xi-rong, ZHAO Xi-cheng, WANG Cheng, WANG Xing-yun, LIU Xiao-yan

2011, 31(1): 25-30.

[Abstract](1413) [PDF 897KB](202)

Abstract:
Microstructural evolution of commercially pure titanium(CP-Ti) produced by equal channel angular pressing(ECAP) at room temperature was analyzed with optical microscope and transmitted electron microscope.The experimental results show that the microstructural evolution is divided into three stages according to different evolution mechanisms.The first regime is the dislocation sliding and twinning mechanism when the true strains are ε ≤1.27.It is proven that the grain size was fined from ~23μm to ~0.35μm and shear bands within high density dislocation and twins were formed.The second regime is the dynamic recovery mechanism when the true strains are 1.27ε2. 54.In this procedure typical subgrain structures with the average grain size ~0.25μm were formed.The third regime is non-equilibrium subgrain boundary rotating mechanism when the true strains are ε≥2.54.After ECAP for 8 passes at room temperate,a homogeneous array of grains with equiaxed high angle boundaries was produced and the average grain size was measured as ~0.2μm.

Effect of Single-side Injection Quenching Parameters on Cooling of 7050 Aluminum Alloy Plate

CAO Sheng-qiang, XIONG Chuang-xian, DENG Yun-lai, ZHANG Xin-ming

2011, 31(1): 31-35.

[Abstract](1246) [PDF 1186KB](183)

Abstract:
Impingement heat transfer is not only related to the types of fluid,the impacted surface morphology and the pressure of injection,but also related to the size and layout of nozzles.This article studied the influence of diameter(D) of nozzles,the distance(L) of adjacent nozzles and the injection pressure(P) to the heat transfer in the stagnation and turbulent.The results show that the effect of heat exchange in turbulent region of samples centre is stronger than that of stagnation region by 500kPa impinging.When D and P is fixed,different L has different influence on the cooling of thick plate.The smaller the L,the greater the mutual interference of adjacent vortex,and at the same time the turbulent cooling intensity increased.When L/D=8~14,it appears trough at the average cooling rates from 470℃ to 300℃,while when L/D=14~20,it appears peak.

TC4 Titanium Alloy Welded by Ultra-sonic Pulse TIG Welding

XU Hai-ying, QI Bo-jin, ZHANG Wei, ZHAO Hai-tao

2011, 31(1): 36-40.

[Abstract](1316) [PDF 1052KB](250)

Abstract:
Firstly,the traits about ultra-sonic pulse TIG welding technology had been introduced in this paper.The disciplinarian of peak current and pulse frequency influence to arc welding plasmas flow force had been analyzed especially.Several TC4 titanium alloy workpieces had been welded by ultra-sonic pulse TIG welding and conventional direct current TIG welding technology respectively.In order to detect blowhole faults in these weld beads,X-radial check-up had been introduced.By these detection results,several of process mechanisms to make blows overflow fleetly,which aroused by the ultra-sonic pulse TIG welding,had been analyzed.These welding joints without faults had been made tensile properties detection samples.A series of tensile properties data had been obtained.By means of scanning electron microscope,the relationship between microstructure and these strength performances had been studied.In comparison with conventional direct current TIG welding technology,blowhole faults has been reduced by introducing 60kHz and 80kHz ultra-sonic pulse TIG welding technology.It also shows that welding joints specific elongation is improved obviously with the pulse current frequency being increased.

Effect of Process Parameters on Residual Stress and Wear and Corrosion Resistance of 7022 Aluminium Alloy by FSW

WANG Hong-feng, ZUO Dun-wen, SHAO Ding-lin, LI Guang, DONG Chun-lin

2011, 31(1): 41-47.

[Abstract](1305) [PDF 2012KB](292)

Abstract:
7022 aluminium alloy plates with the thickness of 10mm are welded by friction stir welding under different welding parameters.The residual stress of specimen is detected by X-ray.The wear property is studied by friction and wear testing machine,and the wear morphology is observed by three-dimensional topography instrument.Corrosion test is done in Na2SO4 with pH=5,and corrosion morphology is observed by SEM.The results show that the residual stress and deformation of all specimens under different welding parameters are small.Friction and wear process is relatively stable,the main forms of wear are plasticyield and abrasive wears,and the wear surface is smooth.The specimen is well corrosion resistance and the main form of corrosion is point corrosion.Corrosion products are mainly Al-oxide,Zn-oxide,Mg-oxide and aluminum sulfate.Comparing the welded specimens under various welding parameters,the best quality of welding specimen is obtained when the rotating speed is 400r/min and the welding speed is 30mm/min.

Influence of Thermo-Mechanical Processing on Microstructure and Mechanical Property of Ti-1023 Alloy

FEI Yue, CHANG Hui, SHANG Guo-qiang, KOU Hong-chao, ZHU Zhi-shou, ZHANG Feng-shou, ZHOU Lian

2011, 31(1): 48-51.

[Abstract](1221) [PDF 1730KB](196)

Abstract:
The effect of thermo-mechanical processing on microstructure and property of Ti-1023 titanium alloy was studied in this paper.Based on the investigation,a better thermo-mechanical processing was obtained.The results show that,during low-temperature(300℃) aging,transitional ω-phase is precipitated,providing a high density of nucleation sites for the secondary α phase,so uniformly distributed α laths are obtained by two-step aging.During hot rolling,β grains are refined and defects are generated.The defects assist the nucleation of secondary α phase during aging.Therefore the strength and plasticity of Ti-1023 alloy are improved by the combined action of two-step aging and hot rolling.After deformation(deformation temperature and deformation reduction are 845℃ and 45%,respectively) and two-step aging(300℃/8h+500℃/16h),the microstructure of Ti-1023 alloy is refined which results in a finer strength and plasticity match.

Intergranular Resistance of A Zirconium Microalloyed 6013 Type Aluminum Alloy

ZHANG Fu-bao, XU Xiao-jing, WU Gui-chao, WANG Bin, LUO Yong, SONG Tao, CHENG Xiao-nong

2011, 31(1): 52-55.

[Abstract](1276) [PDF 517KB](218)

Abstract:
The intergranular resistance of a zirconium microalloyed 6013 type(Al-1.35%Mg-1.03%Si-0.895%Cu-0.539%Mn-0.112%Zr-0.436%Zn) aluminum alloy was investigated.The results show that the alloy homogenized at 470 ℃ for 24h,deformed 150%,solution at 560 ℃ for 2h,aged at 151 ℃for 8h and 191℃ for 8h exhibits well intergranular resistance.According to GB/T 7998—1987and ASTM G110-92 standards,the maximum corrosion depth of the zirconium microalloyed 6013 type aluminum alloy is only 227.23 μm with the microhardness 147.05 HV,indicating better than that of 6061-T6(solution at 560 ℃ for 2h and aged at 160 ℃ for 2h) alloy.Such performance can be explained by the addition of zirconium and the character of main componets,which are favorable for grain refinement,smaller and finer distributed precipitates.

Effects of Particle Content and Granularity on Hot-Deformation Behavior and Microstructure of SiC_P/Al Composite

ZENG Li, REN Xue-ping, CUI Yan

2011, 31(1): 56-61.

[Abstract](1197) [PDF 1346KB](204)

Abstract:
SiCP/Al Composites with various volume fraction were prepared by pressureless infiltration.Hot(above melting point of matrix) compression on the composite was tested.The flow stress behavior of composite with different contents and granularitie standards was rearched.Effects of particle content and granularity on microstructure of SiCP/Al composite with high volume fraction were observed and analyzed by using SEM.The results show that: SiCP/Al Composite with Higher Fraction shows Pseudo-plastic deformation during hot compression;Effect of particle granularity on the flow stress has two steps;The effecting law of particle content and granularity on microstructure of SiCP/Al Composite conforms to its flow stress behavior;SiCP/Al Composite with 55% Fraction and F220 granularity standard shows Pseudo-plastic deformation during hot compression,effects of hot compression on particle disbution and size are more obvious than other composites.

Modified Benzoxazine and its Glass Cloth Laminate

ZHENG Lin, ZHANG Chi, WANG Zhou-yi, ZHAO Pei, LIU Xiang-yang, GU Yi

2011, 31(1): 62-66.

[Abstract](1267) [PDF 1518KB](296)

Abstract:
A modified benzoxazine matrix resin(BEP) which can be used for advanced composite was prepared through the blend of M-benzoxazine(BOZ-M),F-51epoxy resin and Novolac resin.The BEP resin-cast and its E-glass-cloth laminate were prepared as well.The test results indicated that the curing temperature of BEP resin was lower compared with BOZ-M resin.The BEP resin cast had excellent heat-resistance and mechanical properties.The glass transition temperature(Tg) and the elongation at break of the cast were improved to 220℃ and 2.7%,respectively.The BEP/E-glass cloth laminate had high strength and modulous at room temperature,and it also had excellent retention of mechanical properties at 180℃.

Optimal Temperature Profiles for Modified BMI Resin Matrix in Curing Process

LI Du-ning, NIE Yu-feng, LIU Yun-fang, LIANG Bin, CAI Li

2011, 31(1): 67-72.

[Abstract](1249) [PDF 1843KB](199)

Abstract:
A three-dimensional model considering the heat conduction equation and the cure kinetics model is used to simulate the resin film infiltration(RFI) curing process of the modified bismaleimide(BMI) resin matrix.The finite element method and the finite difference method are used to discretize the governing equations.In order to measure the quality of cure,two new control parameters are used in the optimal control of temperature for the curing process.The numerical results show that both the temperature and the cure degree within the component are higher than those on the surface;the dwell temperature and the starting time have great effects on the uniform of the curing degree and the temperature.The simulation results play a significant role on planning the optimal curing process.

Experimental Study on Impact Damage Characteristics and Residual Compressive Strength of Composite Laminates

LIN Zhi-yu, XU Xi-wu, ZHU Wei-yao

2011, 31(1): 73-80.

[Abstract](1207) [PDF 2512KB](208)

Abstract:
Composite laminates of two typical systems(T300/QY8911 and T300/5405) and layers were conducted under three kinds of support conditions(no support,rib flange support and beam or stringer flange support) and six impact energy levels,to study the impact damage characteristics and residual compressive strength.The relationship between impact energy,support conditions etc.and impact damage characteristics were studied.The dent depth and damage area can be used to characterize the impact damage;the resin crack length can not be used to characterize the impact damage.And increasing backup support stiffness can decrease the damage caused by impact.The residual compressive strength after impact decreases while increasing the impact damage energy.And increasing backup support stiffness can increase the residual compressive strength after impact.

Study on Piezoresistive Properties of Silicon Rubber Composite Filled with Aligned Micron Iron Powders

LIU Zhao-wa, ZHANG Bang-wen

2011, 31(1): 81-86.

[Abstract](1237) [PDF 1398KB](262)

Abstract:
Silicon rubber filled with aligned iron powders through the process of magnetic field assisted curing was prepared.The resistance dependence upon filler content and pressure was tested.The results show the composite samples of resistance of more than 1010Ω exhibit negative piezoresistivity,while those of resistance of less than 1010Ω exhibit positive piezoresistivity;the silicon rubber filled with 10%~50% iron powders in weight has a sharp increase in resistance up to 3~5 orders of magnitude close to 0.2 MPa,but the system containing 50% filler obtained under a 0.2T magnetic field exhibits a linear positive piezoresistivity.The underlying mechanism is correlated with the diversity in configuration of aligned microstructure in the rubber induced by magnetic field.

AZ31 Magnesium early Mechanical Performance Degradation Nondestructive Testing Using Nonlinear Ultrasonic

WU Bin, YAN Bing-sheng, HE Cun-fu, JIAO Jing-pin

2011, 31(1): 87-92.

[Abstract](1250) [PDF 1466KB](262)

Abstract:
Toward the problem of the metal material early degradation of mechanical properties,this research developed a robust experimental procedure.Using this system,ultrasonic nonlinearity parameters of AZ31magnesium monotonic load and fatigue samples were measured.The experimental results show that there is a significant increase inβlinked to magnesium mechanical performance degradation,into plastic deformation stage and before the fatigue life of 55%.Monotonic load sample was observed by optical microscopy in the same place,dislocation slip bands increase with stress.Macro-mechanics,nonlinear ultrasonic testing and microscopic observation results show that ultrasonic nonlinearity parameters as a bridge between micro and macro can characterize the mechanical properties of early degradation.However,in the context of low-cycle fatigue,changes of loading stress and the fatigue model with tension-tension fatigue and tension-compression fatigue had no significant effect to the experimental results.

Defect Analysis and Ultrasonic Testing of Isotropic Pyrolytic Carbon

WU Jun-feng, BAI Shuo, ZHANG Hai-feng, HE Ye-hong, YANG Jian, WEI Tian-yang, LIAN De-liang

2011, 31(1): 93-96.

[Abstract](1257) [PDF 782KB](214)

Abstract:
Internal defects and nondestructive testing of isotropic pyrolytic carbon(IPyC) for high performance mechanical seals were studied by the polarized light microscopy(PLM) and ultrasonic flaw detector.PLM observations show that the internal defects in the IPyC include three main types of anisotropic inclusions,cracks and isotropic inclusions.Ultrasonic tests show that the pulse-echo technique is a valid method to detect internal defects in the IPyC products.And now,this technique has been successfully applied to the batch testing of the IPyC products.

2011 Vol. 31, No. 1