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      20 September 2015, Volume 43 Issue 9 Previous Issue    Next Issue
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    Effect of Mn Content on Microstructures and Mechanical Properties of Hot-rolled Ultra-low Carbon Ti Low Alloyed Steel
    MA Ya-na, DU Lin-xiu, HU Jun
    2015, 43 (9): 1-5.   DOI: 10.11868/j.issn.1001-4381.2015.09.001
    Abstract ( 894 ( PDF (3046KB)( 145 Citation
    Based on conventional C-Mn steel, low alloyed element Ti was appropriately added to the experimental steels, and the content of Mn was adjusted. Meanwhile, the simple thermo mechanical control process (TMCP) was adopted. As a result, the good microstructural morphology and nano-scale precipitates were obtained. Therefore, the strength of steel plate obviously increased under the premise of guaranteed good elongation, and the cost of steel was reduced significantly. The microstructures were observed by OM, SEM, and TEM. The results show that when Mn content in the experimental steels increases from 1.05% (mass fraction) to 1.5%, the average grain size is refined from 6.4μm to 5.2μm, the nano-scale precipitates of TiC increase evidently. At the same time, the yield strength, the tensile strength and elongation increase by 56.7, 42.2MPa and 1.2%, and reach 558.7, 662.2MPa and 22.4%.
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    Effect of pH Value on Photocatalytic Properties of BiVO4 Prepared by Ethylene Glycol Sol-gel
    WANG Min, ZHENG Hao-yan, YANG Chang-xiu, GAO Xing-ying, DONG Zhu-xi-wen, LUO Yang, CHEN Yao
    2015, 43 (9): 6-11.   DOI: 10.11868/j.issn.1001-4381.2015.09.002
    Abstract ( 858 ( PDF (3486KB)( 290 Citation
    The visible-light-driven BiVO4 photocatalysts were synthesized by ethylene glycol sol-gel method. The effect of different pH values on microstructure and photocatalytic properties of BiVO4 was studied. The samples were characterized by SEM, XRD, XPS and UV-Vis DRS analyses. The results show that all samples have high purity and all samples are monoclinic.The morphology and photocatalytic properties of the samples change when the pH value changes. When the pH value is 5, the sample is irregular lamellar structure;when the pH value increases to 7 and 9, the sample shows obvious granular structure and much less sample for the irregular structure;when the pH value increases to 11 and 13, the granular structure has the phenomenon of aggregation. The sample of pH=9 has the smallest band gap energy and the minimum grain size, and shows the highest photocatalytic activity. The total decoloration rate of methyl orange is 66.23% under 250W metal halide light for 50min.
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    Pitting Nucleation of 316L Stainless Steel in Different Environments
    WANG Jing, SHANG Xin-chun, LU Min-xu, ZHANG Lei
    2015, 43 (9): 12-18.   DOI: 10.11868/j.issn.1001-4381.2015.09.003
    Abstract ( 755 ( PDF (2579KB)( 258 Citation
    Effect of temperature, concentration of chloride ion and dissolved oxygen concentration on pitting nucleation of polished 316L stainless steel was investigated using long-term immersing experiment and cyclic potentiodynamic polarization curves. Pitting initiated time and location in different artificial sea water environments were determined. The results show that pitting nucleation can be inhibited with increasing dissolved oxygen concentration, which is different from effect of temperature and chloride ion. For 316L stainless steel, after immersed in 10% (mass fraction) NaCl solution with 8×10-6 dissolved oxygen concentration at 4℃, local destroy occurs on the surface passive film, pitting nucleation time is 60-70 days, and MgO-Al2O3 series and CaO-SiO2 oxide series non-metal inclusions exist at the pitting nucleation sites. After immersed in artificial sea water at 4℃, and with 0.02×10-6 dissolved oxygen concentration, the time for pitting corrosion appears on the surface of 316 stainless steel is 70-80 days.
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    Preparation and Friction Properties of Self-lubricating Layer on Bearing Balls by Ball Milling
    TAN Ying-mei, CAO Guo-jian, LI Shuang, GU Le
    2015, 43 (9): 19-24.   DOI: 10.11868/j.issn.1001-4381.2015.09.004
    Abstract ( 765 ( PDF (6448KB)( 183 Citation
    A self-lubricating layer on bearing balls was fabricated by ball milling of MoS2 powder in a vacuum container with bearing balls. The influence of ball milling time on the self-lubricating layer at the rotation speed of 200r/min was investigated. The morphology and elements distribution of the self-lubricating layers under different ball milling time were observed using the scanning electron microscope and EDS spectrum analysis.The results show that with ball milling time, the coating surface morphology changes little, thickness of the lubricating layer increases firstly and then decreases, Mo is distributed first evenly and then dispersely. Thickness and uniformity of element in the coating surface after ball milling for 5h are the best. The friction test results of the coatings show that lubricating effect is obvious with the ball milling for 1h and 5h while the lubricating effect is not obvious with ball milling for 10h. The self-lubricating layer fabricated by the ball milling for 5h has the best lubricating effect.
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    Anti-icing and Anti-adhesion Behavior of Superhydrophobic Aluminum Alloy Surface
    YAN Zhong-na, CHE Yan-hui, FENG Li-bang, QIANG Xiao-hu, LIU Yan-hua
    2015, 43 (9): 25-29.   DOI: 10.11868/j.issn.1001-4381.2015.09.005
    Abstract ( 978 ( PDF (2068KB)( 241 Citation
    A superhydrophobic aluminum alloy surface was successfully prepared via a one-step immersion method in stearic acid-alcohol-water solution. The contact angle can reach 156.2° while the sliding angle is less than 5°. The wettability, surface microstructure and chemical structure, anti-icing, and anti-adhesion behavior were investigated by means of contact angle measurement, SEM, FT-IR, freezing and anti-adhesion experiments, respectively. Results indicate that the micro- and nano-scale porous structure together with the grafted hydrophobic alkyl long chains endows the aluminum alloy surface with the superhydrophobic property. Just grounded on the peculiar rough structure and chemical composition, the resulting superhydrophobic aluminum alloy surface possesses excellent anti-icing and anti-adhesion behavior.
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    Effect of Alloying Elements on Mechanical Behavior of Fe-Mn-C TWIP Steel
    WANG Yu-chang, LAN Peng, LI Yang, ZHANG Jia-quan
    2015, 43 (9): 30-38.   DOI: 10.11868/j.issn.1001-4381.2015.09.006
    Abstract ( 828 ( PDF (5006KB)( 464 Citation
    The effect of alloying elements on mechanical behavior of Fe-Mn-C TWIP steels was investigated by thermodynamic calculation, static tensile test, XRD, OM and SEM. Results indicate that with manganese content increasing, the yield strength and tensile strength of TWIP steels decrease, while the total elongation varies oppositely. As carbon content increases, the yield strength and tensile strength increase initially and then decline with the maximum located near 0.6%(mass fraction) carbon. When Mn is at 20%, the elongation of TWIP steel increases with carbon content increasing, but exhibits reversed trend in the steels with 22% manganese. The product of tensile strength and elongation increases with manganese content increasing, and it is more obvious in the TWIP steels with 0.4% carbon. As the manganese content is equal to 20%, the product of tensile strength and elongation increases with carbon content increasing. However, for the specimens alloyed with 22% manganese, the product of tensile strength and elongation decreases with carbon content increasing.
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    Analysis of Tribological Property and Mechanism of Solid Lubrication on 45 Steel Bond-type Laser Micro-textured Surface
    HUA Xi-jun, WANG Rong, ZHOU Wan, LIU Kai, FU Yong-hong, JI Jing-hu
    2015, 43 (9): 39-45.   DOI: 10.11868/j.issn.1001-4381.2015.09.007
    Abstract ( 720 ( PDF (5832KB)( 266 Citation
    Q switched diode-pumped solid-state Nd: YAG laser was adopted to carry out texture processing on the surface of 45 steel. Rolling friction property test of textured samples filled with MoS2 composite solid lubricant containing different mass fractions of PI was examined by a pin-plate line contact friction and wear tester under different working conditions. Wear morphologies and elements distribution were observed and analyzed by SEM. The results indicate that the friction coefficient of textured surface which is filled with bond-type MoS2 solid lubricant decreases as the load and speed increase, and the composite lubricant containing MoS2 plus 20%(mass fraction) PI has the best anti-friction property. The textured surfaces exist oxidation wear, abrasive wear and adhesive wear in the condition of line contact rolling. High speed and heavy load can promote transfer films forming on the counterpart face, and show good anti-friction performance.
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    WSt Model of Estimating Weld Line Performance and Its Verification
    WU Xiong-xi, LIU Jian
    2015, 43 (9): 46-52.   DOI: 10.11868/j.issn.1001-4381.2015.09.008
    Abstract ( 689 ( PDF (2870KB)( 172 Citation
    The parameters of melt converging angle, flow front temperature, pressure were proposed to characterize the performance of weld line and the WSt model was established to judge the quality of weld line. Based on this, the quality of weld line was contrasted between ordinary molding and rapid heat cycle molding(RHCM) under the same processing parameters. The wind deflector was produced to verification.The results indicate that the weld line performance increases from 0.681 to 0.819, with an increase of 20.3%. And through the tensile experiment of the wind deflector, it can be found that the tensile strength of wind deflector increases from 45.3MPa to 53.8MPa. The strength increases by 18.8%, which is close to 20.3%, as predicted by WSt model.
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    Temperature Evolution in Fatigue Test of 2024 Aluminum Alloy Weld Fabricated by Friction Stir Welding
    WANG Chang-sheng, XIONG Jiang-tao, LI Jing-long, LI Peng, ZHANG Fu-sheng, YANG Jun
    2015, 43 (9): 53-59.   DOI: 10.11868/j.issn.1001-4381.2015.09.009
    Abstract ( 661 ( PDF (4748KB)( 352 Citation
    The weld joints were fabricated by friction stir welding (FSW) on 8mm thick 2024-O aluminum alloy with a rotating speed of 300r/min and a welding speed of 60mm/min. The microstructure and mechanical properties of parent material and weld joints were investigated. The fatigue tests were conducted on both parent metal and weld joint, during which the surface temperatures were recorded by an infrared thermal imager. The results show that the welds exhibit high gradient inhomogeneity in microstructure, and have good fatigue properties. The thermal mechanical affected zone (TMAZ) in advancing side is the weak area as examined by the tensile tests. The temperature change of the specimen surface of the parent material meets the characteristic of "three stages". Surface temperature variation tendency of the FSW welds is the same with that of the parent material in the first stage and the third stage, but has a downward trend in the second stage. The grains of the weld nugget zone and TMAZ accumulate lots of elastic and plastic strain energy through cyclic softening in the second stage that depress the conversion rate of mechanical energy to thermal energy.
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    Tensile Properties of Glass Fiber Reinforced Aluminum Orthorhombic Laminate
    WANG Ya-jie, WANG Bo, ZHANG Long, MA Hong-yi
    2015, 43 (9): 60-65.   DOI: 10.11868/j.issn.1001-4381.2015.09.010
    Abstract ( 645 ( PDF (1989KB)( 159 Citation
    The influence of different layout sequence on the tensile properties was investigated by tensile tests of two group of glass fiber reinforced aluminum orthorhombic laminate with different sequences.The test results show that tensile properties and stress-strain curves of two groups of specimens under loading are almost the same. As a result, the tensile properties have nothing to do with the fiber layup sequence. A modified theory of metal volume fraction is put forward to precisely predict tensile properties including elastic modulus, yield stress and tensile strength. According to acoustic emission(AE) data and pictures of failed specimens, the damage process and failure mechanism of two groups of specimens were analyzed. The results show that the layup sequence has a considerable effect on the damage process and failure mode of the material. Finally, simulation and analysis were carried out on the tensile performance of the specimens using finite element methods. The simulated results are in good agreement with experimental values.
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    Influence of Mode III Load Component on Fracture Toughness of Casing-drilling Steels with Different Microstructures
    XU Tian-han, FENG Yao-rong
    2015, 43 (9): 66-73.   DOI: 10.11868/j.issn.1001-4381.2015.09.011
    Abstract ( 629 ( PDF (5671KB)( 172 Citation
    The mixed-mode I/III fracture toughness of casing-drilling steels with different microstructures was investigated by means of fatigue testers and SEM. The results show that JT of both PF and FBM steels firstly slightly increase with the increase of mode III load component and then decrease continuously, whereas that of TM steel decreases monotonically, which can be attributed to the different fracture surface morphology resulting from the remarkable different microstructure. Meanwhile, it can be found that TM steel possesses the maximum JT and PF steel possesses the minimum JT, respectively, that of FBM is in the middle under different mode III load components. For the three steels, JI and JIII exhibit linear relationship, and the higher the strength, the lower the linear coefficient, the easier to occur fracture under shearing load.
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    Velocity Correction of Delay Time and Inspection for Composite Materials Using Ultrasonic Phased Array
    XU Na, SHA Zheng-xiao, SHI Yi-wei
    2015, 43 (9): 74-79.   DOI: 10.11868/j.issn.1001-4381.2015.09.012
    Abstract ( 880 ( PDF (4161KB)( 700 Citation
    Since velocity of composite material is related to propagation direction, a velocity correction method of delay time calculation was proposed. Propagation characteristics of steering and focusing beams in composite materials were researched using numerical simulation method of finite difference time domain to verify the posed velocity correction method. Ultrasonic phased array inspection system was built and carbon fiber reinforced resin matrix composite plate was detected. The result shows that the signal-to-noise ratio of near surface zone and detection rate of defects are improved obviously using the velocity correction method. The research result indicates that the posed velocity correction method of delay time calculation can solve diffusion of ultrasonic beam and improve inspection ability of anisotropic materials effectively.
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    Effect of Fiber Volume Fraction on Modal Properties of Three-dimension Braided Composite T-beams
    WANG Huan, LI Jia-lu, FAN Wei
    2015, 43 (9): 80-86.   DOI: 10.11868/j.issn.1001-4381.2015.09.013
    Abstract ( 643 ( PDF (2578KB)( 323 Citation
    The modal properties of carbon fiber three-dimension and four-direction braided composite T-beams with different fiber volume fractions were studied by the free vibration method of cantilever beams. The effect of fiber volume fraction on natural frequency and damping was analyzed. The measured and finite element calculated results of natural frequency were compared. The results show that the modal properties of T-beams have nothing to do with the position of excitation point. The natural frequency of the composite T-beams increases and damping properties of the composite T-beams decrease with the increasing of fiber volume fraction. The order of the natural frequency of T-beam could be estimated accurately by the mode shape. The measured results are in agreement with the calculated results.
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    Dynamic Mechanical Response of Cellular Titanium Material
    WANG Jing, REN Hui-lan, HAO Li, NING Jian-guo
    2015, 43 (9): 87-93.   DOI: 10.11868/j.issn.1001-4381.2015.09.014
    Abstract ( 616 ( PDF (1819KB)( 172 Citation
    Shock properties of cellular titanium with regular pores were investigated by one-stage gas gun plate impact technique. With the experimental curves caught by the manganin gauge, the attenuation effect of shock wave propagating through the cellular titanium samples and the adiabatic impact D-u relationship between shock wave velocity and the practical velocity after shock wave are obtained. According to the experiments, a numerical model is built in nonlinear dynamic finite element software. The pressure-time curves of shock wave and the adiabatic relation are obtained from the numerical results, and the polynomial Grüneisen equation of state of cellular titanium is given by numerical simulation. Moreover, with Taylor expansion of the squeezing degree μ, the coefficient of the polynomial Grüneisen equation is deduced by using shock wave relations and the adiabatic relation.
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    Optimized Preparation of Decanoic-palmitic Acid/SiO2 Composite Phase Change Materials Based on Uniform Design
    SHANG Jian-li, ZHANG Hao, XIONG Lei, MA Xiang-long
    2015, 43 (9): 94-102.   DOI: 10.11868/j.issn.1001-4381.2015.09.015
    Abstract ( 785 ( PDF (2591KB)( 201 Citation
    Decanoic-palmitic acid/SiO2 composite phase change materials were prepared with SiO2 as carrier material and decanoic-palmitic acid as phase change material. The effect of every factor on moisture absorbing and desorbing performance and temperature control performance of composite phase change materials was studied by uniform design and multivariate nonlinear regression. The results show that primary and secondary sequence of factors affecting performance is solution pH value> mole ratio between absolute alcohol and tetraethyl orthosilicate> mole ratio between decanoic-palmitic acid and tetraethyl orthosilicate> mole ratio between deionized water and tetraethyl orthosilicate> ultrasonic wave power. The optimized preparation plan is solution pH value 3.62, ultrasonic wave power 100W, mole ratio between deionized water and tetraethyl orthosilicate 9.67, mole ratio between absolute alcohol and tetraethyl orthosilicate 5.21, mole ratio between decanoic-palmitic acid and tetraethyl orthosilicate 0.52.
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    Magnetic Nano-fluid and Its Terminal Technology Application
    SUN Ai-juan, FANG Fen
    2015, 43 (9): 103-112.   DOI: 10.11868/j.issn.1001-4381.2015.09.016
    Abstract ( 818 ( PDF (3324KB)( 194 Citation
    The development of magnetic nanoparticles preparation technology was summarized. The mechanism of stable suspension in the polar or nonpolar carrier liquid during the formation of magnetic nano-fluid and the application progress of its terminal technology were discussed. It is pointed out that further research work on magnetic nano-fluid should include: the major factors influencing the performance of nano-fluid, the compatibility between nanoparticles and the base fluids, the effect of the shape and property of the additive, stability of nano-fluid on the performance of magnetic nano-fluid at high temperature and under long term use conditions.
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