航空材料学报

Effect of Heat Treatment on Microstructure and Tensile Properties of TC21 Titanium Alloy after Thermomechanical Processing in β Field

WANG Xiao-chen, GUOHong-zhen, WANG Yan-wei, WANG Tao, GAO Yan-hua, YAO Ze-kun, ZHAO Zhang-long

2012, 32(1): 1-5.

[Abstract](1912) [PDF 1222KB](252)

Abstract:
The effect of heat treatment on microstructure and tension properties at RT of TC21 titanium alloy isothermal forged was investigated. The results indicate that the multiple thermomechanical heat treatment can greatly strengthen the isothermally forging, while the plasticity descending is caused by the precipitation of the elongated and blocky alpha phase along the primary grain boundary. The effect of dispersion strengthen can be enhanced by means of tougheningstrengthening or quench aging heat treatment, while the plasticity descending is caused by the coarsen interface phase. The nice knitted basket microstructure can be got by isothermal anneal, but the coarsen interface phase is still existed, also the ductility is low. Comparatively, quench aging treatment can guarantee the basket microstructure obtained and relatively eliminate the betabrittleness. So, the quench aging treatment of 900℃/1h，WQ +590℃/4h,AC is recommended.

Effect of Micro Y on Microstructure and Properties of Al-Mg-Si Aluminum Alloy

ZHANG Jian-xin, GAO Ai-hua

2012, 32(1): 6-9.

[Abstract](1821) [PDF 1011KB](301)

Abstract:
The effects of rare earth yttrium on cast microstructure, conductive property and high temperature creep resistance of AlMgSi aluminum alloy are studied when yttrium element is added into the melt in the form of aluminumyttrium interalloy with the range of 0-0.45%. The results indicate that proper yttrium element has the strong refinement on cast microstructure, the average grain size maintains 50 micron or so. The electrical conductivity of experimental materials gets improving to some extent, compared with the original, the best electric conductivity increases by 4%. The thermal stability of experimental sample grows significantly, the hardness and the tensile strength are increased by 30% and 25% respectively.

Effect of Twinning on Moderate Temperature Deformation Behavior of Hot-rolled Mg Alloy

LIU Jun-wei, CHEN Zhen-hua, CHEN Ding, LI Gui-fa

2012, 32(1): 10-14.

[Abstract](1824) [PDF 1331KB](251)

Abstract:
mation process (room temperature～573K) were researched carefully. Then, based on optical microscopy (OM) and transmission electron microscopy (TEM), the deformation mechanism and the type of twinning were explored. The results show that due to the strong texture for the hotrolled sheet,{1011}contract twins play the insignificant role in moderatetemperature deformation process (RT～573K), while basal slip also partly affacts the deformation process. With the increase of temperature and decrease of strain rate, the mount of twins also gradually decreases. The dependence of strain hardening index n firstly decreases with the increase of temperature. This indicated that the hardening effect induced by contract twinning is more significant than twinninginduced softening.

Research on Warm and Hot Mechanical Property of Corrosion Resisting Aluminum Alloy Sheet Based on Uniaxial Tensile Test

LANG Li-hui, XU Ai-jun, LI Tao, ZHAO Xiang-ni

2012, 32(1): 15-19.

[Abstract](1743) [PDF 927KB](272)

Abstract:
The uniaxial tensile tests of corrosionresisting aluminum alloy sheet 5A06O with thickness of 1.2mm were performed at various temperatures ranging from 20℃ to 300℃ and at different strain rates in this study. It is shown that the flow stress and ultimate tensile strength of 5A06O aluminum alloy in uniaxial tension decreases as the deformation temperature increases, while the total elongation increases along with the temperature increases. However，the uniform elongation increases with the temperature increasing from 20℃ to 150℃, while decreases with the temperature increasing from 150℃ to 300℃. In addition, hardening law of 5A06O at different temperatures were analyzed and discussed based on Fields Backofen constitutive equation．It is indicated that the strain hardening index decreases with increasing temperature，while the strain rate sensitivity coefficient increases observably along with the temperature increases.

Investigation on Superplasticity of Ti3Al Alloy Sheet

WANG Xu, CAO Jing-xia, HUANG Xu

2012, 32(1): 20-24.

[Abstract](1903) [PDF 3642KB](207)

Abstract:
Superplastic deformation behavior and microstructure evolution of two hotrolled Ti3Al base alloy sheets with different strain and atypical equiaxed grains were studied in this paper. The results show that, microstructure of the alloy transformed from the initial nonequiaxed microstructure to fine equiaxed microstructure, which is regarded as beneficial for superplastic deformation. The alloy exhibited good superplasticity when deformed at the temperature range of 940~1020℃, with the strain rate of 210-4 ~210-3s-1, the maximum elongation can be reached 859.5% and the strain rate sensitivity index is high at 0.43. The superplastic deformation mechanism of this alloy is mainly for boundary sliding. The effects of deformation inside the grains and dislocation creep during the superplastic deformation are more significant in this atypical equiaxed microstructure condition than those in the typical fineequiaxed conditions. Hotrolled Ti3Al base alloy sheets with atypical equiaxed grains have excellent superplasticity and do not need complex heat treatments, which represents good commercial value.

Evaluation of Microstructure Homogeneity in TC11 Titanium Alloy Blisk Forging

YANG Yan-hui, LIU Dong, LUO Zi-jian

2012, 32(1): 25-29.

[Abstract](1950) [PDF 4462KB](438)

Abstract:
A loss function (LF) based on the distribution of thermalmechanical parameters was proposed referring to the concept of Taguchi method to explore the method of evaluating microstructure homogeneity in disk forging. The forging process of the TC11 titanium alloy blisk and the subsequent evaluation of microstructure homogeneity were analyzed by using FEM and the proposed method. The experiment was performed. The comparison results show that, for TC11 titanium alloy blisk forging, the LF in case 2 proposed in this paper can more appropriately evaluate the microstructure homogeneity, and that the blisk forging with satisfied technical requirements can be obtained when the LF values are in the range of 0.33~0.44

Study on Hot Deformation Behavior of TC4-DT Titanium Alloy

WANG Xiao-fang, CHEN Ming-he, CHEN Wei, ZHU Zhi-shou

2012, 32(1): 30-34.

[Abstract](1878) [PDF 8355KB](243)

Abstract:
Hot compressive deformation of TC4DT titanium alloy was carried out with the hotsimulation machine of Gleeble3500 over the range of deformation temperature from 850 ℃ to 1000℃, strain rate from 0.01s-1 to 10s-1, and the deformation from 40% to 70%.The deformation behavior and microstructure have been analyzed; meanwhile the constitutive model has been set up. The results reveal that TC4DT alloy deforms at temperatures below 950 ℃ when the stress softening phenomenon is very obvious, the deformation mechanisms and deformation activation energy are different from the deformation mechanism above the temperture of 950 ℃. When the alloy deforms at temperatures above 950 ℃, low strain rates(such as=0.01s－1)contribute to the occurrence of dynamic recrystallization behavior, while at higher strain rates(such as =10s－1), only the phenomenon of dynamicrecovery generally occurs. The dynamic recrystallization is inhibited

Brazing of SiO2f/SiO2, SiO2f/SiO2/Cu and SiO2f/SiO2/stainless steel joints

CHEN Bo, XIONG Hua-ping, MAO Wei, CHENG Yao-yong

2012, 32(1): 35-40.

[Abstract](1796) [PDF 1739KB](323)

Abstract:
Brazing of SiO2f/SiO2, SiO2f/SiO2/Cu and SiO2f/SiO2/1Cr18Ni9Ti joints was carried out at 880℃ for 10 min using AgCuTi brazing foils and sound joints were achieved. The results showed that a thin diffusion layer was formed close to the interface of SiO2f/SiO2 matrixes in the three kinds of joints. Elements Ti and O were enriched and TiO2 phase was formed in the diffusion layer. Additionally, in the three brazing seams, AgCu eutectic structures were formed, being made up of white Agbased solid solution and grey Cubased solid solution. The shear strengths of SiO2f/SiO2/Cu and SiO2f/SiO2/1Cr18Ni9Ti joints were 12.4 MPa and 18.4 MPa respectively.One of the key reasons for the low joint strengths is the large residual thermal stress caused by the mismatch of thermal expansion coefficient between the SiO2f/SiO2 composite and the metals to be joined.

Study of Periodical Flow Behavior of Metal Front Stir Pine during the Friction Stir Welding of Aluminum Alloy

HUANG Fu, XIONG Jiang-tao, LI Jing-long, ZHANG Fu-sheng, LI Rui-di

2012, 32(1): 41-44.

[Abstract](1780) [PDF 1691KB](256)

Abstract:
Studied the relative motion between friction stir and welding board of different parameters through highspeed photography, and also analyzed the metal flow during friction stir welding combined appearance of microstructure with transverse cross section and board. It could be divided into two stages which were platform stage and traverse stage in one periodical which equaled to the time that stir rotated one circle spent. In platform stage the function of stir pin was heating the front metal. As the result of this function formed specified thickness layer of viscoplastic metal. In feed stage the viscoplastic metal. In feed stage the viscoplastic front metal was carried integrally by stir pin.

Microstructure and Properties of T Structure Joints by Single Pass Welding and Double Backside Shaping on Titanium Alloy

WANG Min, YANG Lei, YU Ying, WU Lin

2012, 32(1): 45-50.

[Abstract](1739) [PDF 2236KB](239)

Abstract:
T structure parts of titanium alloy are single pass welded and double backside shaped, respectively by TIG welding and laser TIG hybrid welding. The microstructure, tensile, bending and fatigue performance of the two methods have been tested comparably. The results show that the tendency of grain growing in the weld vicinity and HAZ is much lesser. The bending strength of laserTIG hybrid welding is obviously higher than that of TIG welding. The fatigue life of laserTIG hybrid welding joint is 50% more than that of TIG welding joint. So, the general performance of laserTIG hybrid welding joint is better than that of TIG welding

Effect of Ferrous Ion on Sulfate Reducing Bacteria Influenced Corrosion of Mild Steel

WANG Song, LI Xiao-gang, HUANG Yi-zhong, DU Cui-wei

2012, 32(1): 51-56.

[Abstract](1912) [PDF 2547KB](319)

Abstract:
In this investigation, we analyse the corrosion behavior of mild steel immersed in two inoculated cultures with different ferrous concentration-0mg/L and 30mg/L. The optical microscope and electrochemical impedance spectroscopy (EIS) were used to obtain the photos and EIS data of mild steel with different immersing time. The Focus Ion Beam (FIB) was used to observe and cut the corrosion products of mild steel. The EDS was used to analysze the composition of corrosion products. The EIS data was analyzed with equivalent circuit. According to The result of the analysis, the resistance of the biofilm formed on the surface of mild steel immersed in the culture without ferrous ion (sample I) was higher than that immersed in the culture with ferrous ion (sample II). On the contrary, the capacitivity of the biofilm formed on the surface of sample I was lower than that of sample II. From the FIB photos we can learn that compared with sample I, the amount of sticking SRB on the surface of sample II was greater , the biofilm formed on sample II was thicker and was more loose, the corrosion of sample II was more serious. With respect to the EDS result, there is S in the biofilm formed on sample II. To sum up the above, the result of EIS dovetailed with the results of optical microscope、FIB and EDS. Ferrous can speed up the SRB influenced corrosion of mild steel

Study on Preparation of Nanosized Sb and Dispersion of Sb in Liquid Media

XU Jian-lin, YANG Shu-hua, GAO Wei, KANG Zhao, GU Yu-fen, ZHANG Jian-bin

2012, 32(1): 57-62.

[Abstract](1724) [PDF 1835KB](221)

Abstract:
Nano antimony particles with different morphology and size were prepared by electrochemical method (Electrodeposition), while the surface was modified by using OP10. Some methods such as TEM, XRD, FTIR were used for the morphology, size and coating effects analysis of the nanometersized Sb particles. The results showed that there were time effects and current effects when antimony nanoparticles were synthesized. With increasing reaction time, the size of nanoantimony particle became larger and, to some extent, agglomerating phenomenon of nanoantimony particle occurred. When the current density changed within a certain range, the suitable increase of the current density was conducive to the formation of nanoantimony particles. The surface modification of nanoparticles of antimony was obtained mainly by coating of OP10 through chemical absorption between OP10 longchain molecular structure and nanoantimony particle, interaction of hydrogen bond and van der waals force among OP10 longchain alkyl molecular, mutual tangle of molecular chain and mutual permeation of CH bond, while the bond of ether playing a role during the reaction. The dispersion and stability of nano antimony particles in the pure liquid paraffin oil related to their dosage, and the optimum amount is 0.5%.

Preparation and Electromagnetic Characteristic of Novel Carbon Based Composites

WANG Wen, WANG Cheng-guo, GUO Yu, CHEN Yang

2012, 32(1): 63-67.

[Abstract](1739) [PDF 2632KB](383)

Abstract:
Three novel carbon based composites were prepared by using Fe, nanoFe, FeC2O4(2H2O and polyacrylonitrile(PAN) as precursors respectively. The phase composition of the composites was analyzed by Xray diffraction. Electromagnetic and microwave absorption properties of the composites and pure carbon material were investigated in the frequency range of 2~18 GHz. The results show that C and Fe3O4 are the chief components, and the reflection loss values of below-10dB were achieved in the frequency range of 12.7～18 GHz with thicknesses were 1.9 and 2.2mm,for the composites using Fe and nanoFe as precursors, respectively. When the thickness increased to 2.5MM,the minimum reflection loss value of -46 and -29.8 dB were observed. It indicates that the composites can improve the impedance matching and the microwave absorption capability of the carbon matrix.

Effects of nSiO2 on Growth Dynamics of Alumina Coatings Formed on 7A52 Aluminum Alloy by Micro arc Oxidation

MA Shi-ning, SUO Xiang-bo, QIU Ji, ZHU Hai-yan

2012, 32(1): 68-71.

[Abstract](1798) [PDF 1289KB](228)

Abstract:
Al2O3 coatings embedded with SiO2 nanoparticles were produced on 7A52 aluminum alloy by adding SiO2 nanoparticles into the electrolyte. The effect of nSiO2 on the growth kinetics of the microarc oxidized coating under the two modes of constant voltage and constant current was investigated. The results show that nanoSiO2 increased the growth rate of microarc oxidized coating and the current efficiency. NanoSiO2 is formed impurity energy level and narrowed band gap, so that impurity discharge is existed during the breakdown process and promoted the microarc oxidation process of electrical breakdown, resulting in the improvement of the growth efficiency of microarc oxidized coating.

Pulsed Thermography of Composite Components Used in Aerospace Applications

LIU Ying-tao, GUO Guang-ping, YANG Dang-gang, HE Fang-cheng, HUO Yan, ZHAO Shi-bin

2012, 32(1): 72-77.

[Abstract](1843) [PDF 5464KB](460)

Abstract:
The principle, characteristics and application of infrared thermographic nondestructive testing were described shortly in this paper. The influence of primary parameters in infrared flash thermography testing was analyzed. Experiments on composite components were made. The results of infrared flash thermography testing on foam sandwich structure and honeycomb sandwich structure with thin skin were legible and full of inside information of the structures. The defects of disbonding, impact damage and water in honeycomb core were found in the testing, so infrared flash thermography can be used to test radomes inservice. The results of experiments also show that infrared flash thermography is propitious to nondestructive testing of thin laminate structures.

Mechanical Behavior of a Stainless Steel Material at Elevated Temperatures and High Strain Rates

ZHANG Hong, SUO Tao, LI Yu-long

2012, 32(1): 78-83.

[Abstract](1797) [PDF 2162KB](728)

Abstract:

Finite Element Simulation of Residual Stress Field Induced by Ultrasonic Impact Treatment

LI Jin-yi, LING Xiang, ZHOU Jian-xin

2012, 32(1): 84-88.

[Abstract](1843) [PDF 3481KB](321)

Abstract:
A 3D finite element model predicting the residual stress distribution induced by ultrasonic impact treatment (UIT) in the AISI 304 stainless steel was established. Effects of impact velocity, pin size, impact time, interfacial friction, multiple impacts and coverage were considered during the simulation. The results show that impact velocity, pin size, impact time and interfacial friction affect the final residual stress field. Impact velocity and pin diameter have a great influence on the distribution of residual stress field. The depth of the stress layer and the residual stress value increase along with the rising of pin diameter or impact velocity. However, friction coefficient has little influence on impact. According to the increase of impact time, the ultrasonic impact strengthening characteristic is obvious and the depth of the stress layer increases. Along with the increase of the coverage, the compressive residual stress layer gets thicker, but the formation of the maximum compressive residual stress value decreases.

Identification of Interface Fracture Parameters of Fiber Reinforced Composite by Using Kalman Filter Technology

HE Zhou-li, XU Fei, DUAN Min-ge

2012, 32(1): 89-94.

[Abstract](1751) [PDF 1208KB](212)

Abstract:
|The fiber reinforced composite has the advantages of low density, high strength and stiffness, high fatigue resistance, high abrasion and corrosion resistance, good molding and high temperature resistance, which makes it as the brightest material applied in the aerospace and aviation field. In this paper, Kalman filter technology which originally came from the field of signal control is introduced as an inverse analysis to identify the interface parameters of composites. By performing detailed FEM simulation and using the experimental data of the force and displacement curve of the fiber pullout test, the Kalman filter recursive process is successfully carried out to identify the values of the shear strength and the fracture energy G for the SiC（SCS6）/Ti material interface. The great advantage of this inverse technology is that the influence of experimental noise can be taken into account. The calculation results show that the rate of convergence to the correct solution depends on the number and the initial estimation of unknown parameters to be identified and the accuracy of the measured data. Our analysis demonstrates that the proposed approach is suitable and capable in the identification of material parameters of the composite interface.

2012 Vol. 32, No. 1