20 February 2017, Volume 41 Issue 2
    

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    Technical Review
  • SUN Xiao-yang, WANG Ze-hua, ZHOU Ze-hua, SHAO Jia, SHENG Huan, QIAN Kun-cai, WU She-zhang
    Materials For Mechanical Engineering. 2017, 41(2): 1-7,97. https://doi.org/10.11973/jxgccl201702001
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    Fatigue failure analysis processes and fatigue life assessment methods for metal materials are reviewed. The evaluation theories and models which were used widely in engineering, such as the Miner linear cumulative damage theory, the energy method, the elastic-plastic finite element method, the overload retardation model, are mainly introduced. The application conditions, advantages and disadvantages of these methods and models are also analyzed. With the development of the experimental technique and computer simulation technology, the assumptions will be more accuracy. Therefore the combined method of experiment and computer simulation for the fatigue life prediction and assessment of metal materials will be one of the most important development directions in the future.
  • ZHANG Xin, ZHANG Zhi-gang, WANG Xiao-ru, LI Shao-hua
    Materials For Mechanical Engineering. 2017, 41(2): 8-14,111. https://doi.org/10.11973/jxgccl201702002
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    The research progress on reheat cracking of welded joint of heat-resistant steel pipe for thermal power plant boiler is summarized from the aspects such as reheat cracking characteristics, formation mechanism, and preventive measures. However, the research and application of reheat cracking is not very clear and unitary, and the explanation for the reheat cracking phenomenon of some materials is not enough, even contradictory. In the future, the research on reheat cracking of the welded joint of heat-resistant steel pipe for power plant boiler should be focused on the material composition and performance optimization, precipitation, failure model, high resolution microstructures, etc. Meanwhile, the reheat cracking evaluation system should be established to realize the prediction and evaluation of the reheat cracking.
  • Testing & Research
  • QI Shuang, DUAN Lin-hai, ZENG Tao, BAI Yang, CAO Jian-wu
    Materials For Mechanical Engineering. 2017, 41(2): 15-19,101. https://doi.org/10.11973/jxgccl201702003
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    Pb0.97-xLa0.02BaxZr0.55Sn0.38Ti0.07O3 (x=0, 0.09, 0.11, 0.13, mole fraction) antiferroelectric ceramics were synthesized by conventional solid state reaction method, and then the effects of Ba doping concentration on the microstructure, dielectric property and energy storage property of the ceramics were studied. The results show that Ba was capable of diffusing into the ceramic lattices to form a perovskite structure. With the increase of the Ba doping concentration, the antiferroelectric-paraelectric phase transition temperature of the ceramics decreased while the dielectric permittivity increased. The energy storage density of the ceramics at 5.4 kV·mm-1 reached 0.7 J·cm-3 with x value of 0.09. The applied electric field intensity was lower than that reported in literatures, indicating that the doped Ba can decrease the applied electric field intensity. The relationship between Ba doping concentration and the energy storage property of the ceramics was linear.
  • LIU Jiang-bo, WANG Zhou-fu, WANG Jing-wei, LIU Hao, WANG Xi-tang, MA Yan
    Materials For Mechanical Engineering. 2017, 41(2): 20-23. https://doi.org/10.11973/jxgccl201702004
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    With the magnesia-rich spinel as the main raw material, adding four alumina sources of activated alumina, ρ-Al2O3, Al(OH)3, industrial alumina, respectively, the magnesium aluminate spinel was prepared after sintering at temperatures of 1 550-1 700℃. The effect of alumina source on the sintering behavior of the magnesia-rich spinel was studied, and the phase composition and microstructure of the magnesium aluminate spinel were analyzed. The results show that the effects of different alumina sources on the sintering behavior of magnesia-rich spinel were different. The addition of activated alumina was in favor of the sintering densification, while with the addition of ρ-Al2O3, Al(OH)3 and industrial alumina, the influence was unfavorable. When sintering at the temperature under 1 650℃, the synthetic magnesium aluminate spinel was mainly fabricated by the reaction of free magnesia and alumina, while a little alumina was solid solved in the spinel lattice at the temperature over 1 650℃. After sintering the magnesia-rich spinel with activated alumina at 1 700℃ for 3 h, the obtained magnesium aluminate spinel had a good grain growth and a dense structure.
  • ZHOU Hong-ming, XIA Qing-lu, LI Jian
    Materials For Mechanical Engineering. 2017, 41(2): 24-29. https://doi.org/10.11973/jxgccl201702005
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    Composite stabilizer-stabilized (C-TZP), Y2O3-stabilized (Y-TZP) and CeO2-stabilized (Ce-TZP) tetragonal zirconia polycrystalline ceramics were hydrothermally treated at 200℃ for 0-45 h. The micromorphology, phase composition, and the mechanical properties at different hydrothermal time of the ceramics before and after hydrothermal treatment were studied. The hydrothermal aging mechanism was also analyzed. The results show that with the increase of hydrothermal time, the hardness, bending strength and fracture toughness of three zirconia ceramics all decreased, among which the decrease range of the Y-TZP ceramics was the largest, followed by that of the C-TZP ceramics. Comparing to that before hydrothermal treatment, the volume fraction of the monoclinic phase in Y-TZP ceramics increased by 58% after hydrothermal treatment for 30 h, while that in Ce-TZP and C-TZP ceramics increased relatively little after hydrothermal treatment for 45 h. The hydrothermal aging resistance of the Y-TZP ceramics was the worst. The direct reason for the hydrothermal aging was because of the addition of Y2O3. Decreasing the Y2O3 content and increasing the CeO2 content was in favor of controlling the hydrothermal aging. The hydrothermal aging process coincided well with the chemical etching model of the zirconia ceramics.
  • ZHANG Sa
    Materials For Mechanical Engineering. 2017, 41(2): 30-33,39. https://doi.org/10.11973/jxgccl201702006
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    Lanthanum-doped lead zirconate titanate (PLZT) ceramics were prepared by conventional solid state reaction technique and polarized in different directions. Then the cyclic loading fatigue experiment under an alternating electric field was conducted on the ceramics. The Raman spectra and hysteresis loops were in-situ measured at different cycles, and then the variations of Raman spectra intensity for soft modes and remanent polarization were analyzed. The results show that Raman spectra intensity and ferroelectricity of the ceramics decreased due to the domain switching produced during the fatigue process under the cyclic alternating electric field. With the increase of the cycles, the Raman relative intensity for soft modes and the relative intensity for remanent polarizationin decreased first rapidly then slowly with the same turning point at about 106.2 cycles. The Raman relative intensity for soft modes and the relative intensity for remanent polarizationin of the out-of-plane polarized specimen decreased with the largest reduction among those of non-polarized and in-plane polarized specimens, with the cycle increasing.
  • ZHANG Ke, WU Yuan-yuan, XU Feng, WANG Lei
    Materials For Mechanical Engineering. 2017, 41(2): 34-39. https://doi.org/10.11973/jxgccl201702007
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    The evolution of texture, Taylor factor and disorientation of high carbon steel wire rod during cold drawing was characterized using electron backscatter diffraction. The texture evolution was interpreted in terms of variation of Taylor factor and the mechanism of the evolution was discussed. Meanwhile, the evolution of correlated and uncorrelated distribution of disorientation was preliminarily studied. The results show that with the increase of drawing strain, the relative content of grains with Taylor factor greater than 3 increased, indicating that the 〈110〉-fiber texture changed from the 〈113〉-fiber texture during the successive drawing. Meanwhile, the pearlite colonies were evidently deformed, resulting in the amount of low angle grain boundary increasing. The uncorrelated distribution of disorientation coincided with Mackenzie distribution under relatively small strains, while peaks appeared both at 20° and 50° in the uncorrelated disorientation distribution map under relatively large strains, showing the dislocation multiplication and transformation trend from low angle grain boundaries to high angle grain boundaries.
  • NING Sheng-ke, QIN Jing, MA Bao-ji
    Materials For Mechanical Engineering. 2017, 41(2): 40-44,50. https://doi.org/10.11973/jxgccl201702008
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    The micro-arc oxidation was conducted on AZ91D magnesium alloy surface, and then the corrosive degradation resistance of the non-oxidized and micro-arc oxidized alloys was studied during immersion in the simulated body fluid of 2 mL·min-1 for 5 d. The friction and wear experiment in the flowing simulated body fluid was performed on the micro-arc oxidized magnesium alloy with immersion for 5 d. The effects of load, rotating speed and wear time on the friction and wear properties were investigated and the wear morphology and mechanism were analyzed. The results show that the micro-arc oxide film had a porous structure and local tiny cracks. The corrosive degradation resistance of the micro-arc oxidized magnesium alloy was better than that of the magnesium alloy substrate. During the wear of micro-arc oxidized magnesium alloy with 5 d immersion in the simulated body fluid, the friction coefficient increased with the increasing load and decreased with the increasing rotating speed and wear time, while the wear losses increased with the increase of the load, rotating speed and wear time. The wear mechanism was mainly adhesive wear at the low rotating speed while delamination wear at high rotating speed.
  • ZHANG Jing, ZOU Yong, LI Xin-mei, DU Bao-shuai, LI Xiang-qian
    Materials For Mechanical Engineering. 2017, 41(2): 45-50. https://doi.org/10.11973/jxgccl201702009
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    Some micro-cracks were found in weld metal of P92 steel welded joint in ultra supercritical unit after 8 000 h service, these micro-cracks were observed and analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Morphology, distribution and property of these micro-cracks were analyzed. Results show that both intergranular and transgranular cracks in P92 steel welded joint were presented, and the micro-cracks showed wormy shape with discontinuous distribution. A large number of precipitates were distributed in the front area near the crack tips. The formation of micro-cracks was related with stress and structure of micro-zone, and the micro-cracks derived from low temperature region during welding procedure and formed from interconnection of micro brittle cracks under the influence of stress field.
  • DU Ya-nan, XIE Jian-lin
    Materials For Mechanical Engineering. 2017, 41(2): 51-54,66. https://doi.org/10.11973/jxgccl201702010
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    In order to obtain magnesia stabilized zirconia slurry with good liquidity and stability, the effects of solid content, dispersant addition, slurry pH and milling time on the liquidity and stability of slurry were analyzed by viscosity test, sedimentation test and Zeta potential and particle size test. The results show that with the increase of solid content, viscosity and stability of slurry increase and liquidity decreases. Liquidity of slurry increases and then decreases, and the stability increases and then changes little as the increase of dispersant addition, slurry pH and milling time. Absolute value of Zeta potential of the alkaline slurry is larger and its stability is the best. Zeta potential increases and then decreases with the increase of dispersant addition.When the solid content was 45%, volume fraction of dispersant was 2%, slurry pH was 9 and milling time was 48 h, the ceramic slurry can obtain better liquidity and stability.
  • New Materials & Technology
  • HAN Xue-fei, ZOU Qi, ZENG Tao, YANG Xiao-bo, CAO Jian-wu
    Materials For Mechanical Engineering. 2017, 41(2): 55-58,62. https://doi.org/10.11973/jxgccl201702011
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    (Na0.52K0.44Li0.04)(Nb0.9Sb0.04Ta0.06)O3 piezoelectric ceramics with size of φ15 mm×0.1 mm was prepared by solid-state sintering method, and then the microstructure, electrical property and thermal depolarization property of the ceramics were studied. The ceramics were packaged into a buzzer and the acoustic property of the buzzer was measured and compared with that of the commercial lead-based one. The results show that the ceramics had the pure perovskite phase (tetragonal) structure. Below the Curie temperature (265℃), the piezoelectric constant were about 280 pC·N-1 and reached 89.2% that of the unheating ceramics, indicating the good temperature stability. The sound pressure level of the buzzer made of the ceramics was slightly lower under the conditon of (1-4) kHz/9 V while better under the condition of 2 kHz/3 V than that of the lead-based one. Moreover, the acoustic property of the ceramic buzzer kept stable at temperatures between -40℃ and 85℃.
  • LI Fa-liang, DU Shuang, ZHANG Hai-jun, ZHANG Shao-wei, LU Li-lin
    Materials For Mechanical Engineering. 2017, 41(2): 59-62. https://doi.org/10.11973/jxgccl201702012
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    ZrB2-SiC composite powders were synthesized by the boro/carbothermal reduction method using ZrO2, SiO2, B2O3 and activated carbon as raw materials. The thermodynamic analysis was conducted on the formation process. The effects of synthesis temperature and activated carbon content on the phase composition and micromorphology of ZrB2-SiC composite powders were investigated. The results show that ZrB2-SiC composite powder can be synthesized at temperatures of 1 400-1 450℃. Increasing the reaction temperature was beneficial to the synthesis of ZrB2-SiC composite powder and the relatively pure ZrB2-SiC composite powder was obtained by the reaction at 1 450℃ for 3 h. Meanwhile, the phase composition of the obtained ZrB2-SiC composite powders was basically similiar with the activated carbon of excessive mole fraction of 50% and 75%.
  • WAN Jun, WANG Zhou-fu, TIAN Zheng-quan, LIU Hao, WANG Xi-tang, MA Yan
    Materials For Mechanical Engineering. 2017, 41(2): 63-66. https://doi.org/10.11973/jxgccl201702013
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    The lanthanum aluminate precursor was prepared by the low temperature solid state reaction method using aluminum nitrate nonahydrate and lanthanum nitrate hexahydrate as raw materials and citric acid as complexant. The composition and thermal decomposition process of the precursor were analyzed. Then the lanthanum aluminate precursor was calcined at different temperatures to obtain the lanthanum aluminate powder. The synthesis temperature and the calcination temperature effect on the morphology, grain size and specific surface area of the lanthanum aluminate powder were all studied. The results show that the complex compound containing La-O-Al bond was formed in the lanthanum aluminate, and when the calcination temperature reached 700℃, the lanthanum aluminate grains began to form. With the increase of the calcination temperature, the lattice distortion of the lanthanum aluminate grain decreased and the grain size gradually increased, while the crystallinity of the powder increased and the powder particle size decreased gradually. At the calcination temperature of 1 000℃, the obtained lanthanum aluminate powder had the minimal particle size of 0.310 μm and the maximal specific surface area of 16.58 m2·g-1.
  • SONG Xin, CHEN Tie-qiang, HUANG Shao-shuai, ZHENG Hui-ping, ZHANG Xue-feng, BAI Xue-jun
    Materials For Mechanical Engineering. 2017, 41(2): 67-71,76. https://doi.org/10.11973/jxgccl201702014
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    By the reasonable composition design and uncompromising controlled rolling and controlled cooling process, 120 mm thick Q460 steel plate was developed successfully. The effects of rolling process on the microstructure and mechanical properties of the plate were investigated. The results show that under different process conditions, the basic microstructures of the tested plate all consisted of ferrite and pearlite and showed an obvious band-like shape in the core. The strength of the steel plate was slightly improved by the increasing cooling intensity after rolling while the toughness was not ameliorated. The ferrite and pearlite microstructures were obviously refined, the band-like microstructure amount decreased, and the toughness of the steel plate was significantly improved meanwhile the strength kept unchanged by the increase of the intermediate holding thickness.
  • DIAO Yu, TANG Hou-rui, LÜ Peng
    Materials For Mechanical Engineering. 2017, 41(2): 72-76. https://doi.org/10.11973/jxgccl201702015
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    Using graphene oxides prepared by Hummers method and carbon nanotubes with diameters of 30-50 nm and lengths of 50-100 μm as raw materials, the graphene aerogel and graphene/carbon nanotube aerogel were prepared by hydrothermal reduction method followed by freeze-drying treatment. The phase composition, micromorphology and elasticity properties of the aerogels were studied and the effect mechanism of carbon nanotube on the elasticity property was annalyzed. The results show that the two aerogels both had a three-dimensional porous structure. The carbon nanotubes distributed evenly on the graphenes and wrapped the inter wall of the graphene sheets and the connection points between the sheets. The recoverable compressive strain of the graphene/carbon nanotube aerogel was as high as 90%, which was higher than that of the graphene aerogel. The carbon nanotubes can prevent the sliding between the stacked graphene sheets and improve the structure stability of the graphene.
  • ZHU Xiao-gang, SUN Jing, WANG Lian-feng, CHENG Ling-yu, WEN Shan-shan, YANG Yang
    Materials For Mechanical Engineering. 2017, 41(2): 77-80. https://doi.org/10.11973/jxgccl201702016
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    AlSi10Mg alloys were fabricated by the selective laser melting (SLM) with the optimal process parameters. The microstructure, tensile property, impact property and relative density in the directions parallel and perpendicular to SLM forming direction were studied and compared, and the forming quality of SLM formed inclined planes with different inclination angles were also analyzed. The results show that the microstructure in the direction parallel to SLM forming direction was different from that in the direction perpendicular to SLM forming direction. The tensile strength, yield strength, elongation and impact energy of the specimen sampled perpendicular to SLM forming direction was 364 MPa, 303 MPa, 6.7%, 5.1 J, which were higher than that parallel to SLM forming direction; when the inclination angle was less than 45°, the forming quality of the inclined plane was good; the collapsing defects were observed at the bottom of the inclined plane with the inclination angle over 50°.
  • Material Properties & Application
  • LI Hong-wei, YU Nan, LIANG Jun-ping, RAO Xin-yuan, QI Peng-chao, WANG Wei
    Materials For Mechanical Engineering. 2017, 41(2): 81-84. https://doi.org/10.11973/jxgccl201702017
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    Porous SiC ceramic filters with different thickness and apparent porosities of 39.2%, 48.9%, 54.4%, respectively, were sintered at 870℃ for 2 h by changing the content of petrol coke powder (as the pore former). The micromorphology and phase composition of the ceramic filters were analyzed by the scanning electron microscope, energy dispersive spectroscope and X-ray diffraction. Moreover, the effects of thickness and apparent porosity on the water permeation flux of the ceramic filters were investigated by the dead-end filtration. The results show that the microscopic pores distributed uniformly in the porous SiC ceramic filter. With the increase of the filter thickness, the water permeation flux of the ceramic filter showed a linear decrease trend, and with the thickness over 8 mm it would be very difficult for water running through the filters. At the same thickness, with the increase of apparent porosity, the water permeation flux increased rapidly. The influence of the apparent porosity on the water permeation flux was bigger than that of the filter thickness.
  • WANG Chun-guang, WANG Dong-zhe, LIU Hai-ding, LIU Wei, CAI Xin-nan, CHEN Deng-hua
    Materials For Mechanical Engineering. 2017, 41(2): 85-88. https://doi.org/10.11973/jxgccl201702018
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    The uniform corrosion and four point bend-beam stress corrosion tests of iron-nickel-base alloy 925 were conducted in the salt solution containing S, H2S and CO2 at 150℃. The corrosion morphology and corrosion product composition were analyzed and the corrosion reaction mechanism was investigated. The results show that after uniform corrosion testing for 360 h, obvious localized corrosion on the surface of the iron-nickel-base alloy 925 was observed; the calculated uniform corrosion rate was 0.37 mm·a-1; the corrosion product was composed of Fe, Ni and S; the addition of S was the main reason of the alloy localized corrosion. After stress corrosion testing for 1 080 h, no stress corrosion cracking was observed on the alloy; the corrosion product had a large number of element O, indicating that much H2O or OH- participated in the corrosion reaction.
  • YUAN Li-jun, LIU Hao, WANG Zhou-fu, WANG Xi-tang, MA Yan
    Materials For Mechanical Engineering. 2017, 41(2): 89-92. https://doi.org/10.11973/jxgccl201702019
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    CaO-MgO-SiO2 ceramic fibers were prepared by the high-temperature melting method, and then heat-treated at temperatures of 800-1 200℃. The effects of the heat-treatment temperature on the surface morphology and on the hydration resistance of the ceramic fibers were studied. The results show that the crystallization of the fiber changed from the surface crystallization to the overall crystallization due to the increasing heat-treatment temperature, and the fibers showed a coexisting structure of crystalline state and amorphous state. The structure difference between the different temperature heat-treated fibers and the existence of the phase boundary resulted in the different reaction activities between fibers and OH- during the soaking process in the deionized water, furthermore significantly affected the hydration resistance of the heat-treated fibers.
  • ZHAO Xue, JI Deng-peng, ZHANG Mei, ZHOU Xiao-hang, SONG Jia-nan, WAN Zi
    Materials For Mechanical Engineering. 2017, 41(2): 93-97. https://doi.org/10.11973/jxgccl201702020
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    To study the main factors influencing the hole expansion property of FB780 advanced high strength steel, hole expanding tests were carried out according to Chinese standard GB/T 15825.4-2008. The microstructures of the tested steel before and after hole expansion, morphology of burnish zone and fracture zone on the punching surface, hardness profile of the micro-area within 2 mm distance near punch holes, morphology and second phase in the position of the through-wall cracks on the specimens were studied with the help of optical microscope, scanning electron microscope, and micro-hardness tester, etc. The key factors influencing hole expansion property were obtained. The results reveal that key factors influencing hole expansion property of FB780 steel included hardness and microstructure of micro-area near punch hole and quality of punch holes surface. It is found that the hole expansion ratio decreased with the significant increase of hardness of the micro-area near punch holes. Crack's formation and expansion were conducted by microporous gathered mode during hole expansion process. The improvement of microstructure and punching quality was good for hole expansion property.
  • ZHAO Teng, WANG Xi-tang, WANG Zhou-fu, LIU Hao, MA Yan
    Materials For Mechanical Engineering. 2017, 41(2): 98-101. https://doi.org/10.11973/jxgccl201702021
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    Cordierite bonded SiC composite materials were in-situ synthesized by using silicon carbide particles as aggregate, with talc powder, clay and α-Al2O3 powder as matrix materials, and introducing appropriate Al2O3-SiO2 ceramic fiber. The effect of fiber addition on properties of the composite material was studied. The results show that the composite material was mainly composed of SiC and cordierite. With the Al2O3-SiO2 ceramic fiber mass fraction of 8%, the fiber combined with the matrix closely and distributed well. With the increase of fiber addition, the flexural strength of the composite material first increased then decreased, while the thermal shock resistance increased. When the fiber mass fraction was 8%, the composite material reached the largest flexural strength of 33 MPa and had relatively good comprehensive properties.
  • JIN Hui, LI Xin-mei
    Materials For Mechanical Engineering. 2017, 41(2): 102-105. https://doi.org/10.11973/jxgccl201702022
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    Al-Zn-Mg-Cu alloys without and with the addition of 0.1wt% Zr and 0.2wt% La were prepared, respectively, and then were subjected to homogenizing, solution, and aging treatment. The effects of Zr and La addition on the microstructure and mechanical properties of Al-Zn-Mg-Cu alloys were investigated. The results show that with the addition of 0.1wt% Zr and 0.2wt% La, the nucleation rate of the alloy increased, the microstructure distribution was more uniform and the grains were refined; the as-cast hardness, tensile strength and elongation increased by 13.60%, 25.00%, 21.88% comparing to those of without Zr and La; the fracture mode changed from the intergranular fracture of the alloy without Zr and La to the dimple transgranular fracture, indicating the improvement of the alloy toughness.
  • ZHU Lang-ping, LI Jian-chong, MO Xiao-fei, WEI Zhan-lei, LI Yan, LUO Qian, NAN Hai
    Materials For Mechanical Engineering. 2017, 41(2): 106-111. https://doi.org/10.11973/jxgccl201702023
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    The hot isostatic pressing and annealing treatment at different temperatures were successively conducted on a near-α TG6 titanium alloy by precision casting, and then the microstructure and tensile properties of the alloy in different states was studied. The results show that the microstructure of the cast alloy mainly consisted of Widmanstatten structure, and the shrinkage defect existed in the microstructure; the room temperature tensile strength reached 871.3 MPa, while the elongation was only 0.8%; the shrinkage defect became the crack initiation source. After hot isostatic pressing at 900℃, the shrinkage defect was eliminated, the room temperature elongation increased to 3.7%, and the tensile fracture showed features of quasi cleavage fracture. After annealing at temperatures of 700℃-800℃, β lath in the alloy microstructure was dissolved partially and band-like and granular silicide precipitated, meanwhile the α2 phase dispersively distributed in the α lath; the room temperature elongation was improved to over 11%, and the tensile fracture at room temperature and 550℃ showed a mixed fracture of cavitation and cleavage, while those at 650℃ and 700℃ showed characteristics of corrosion cracking.
  • Physical Simulation & Numerical Simulation
  • CHANG Yuan, XU Hong, LAN Xiang
    Materials For Mechanical Engineering. 2017, 41(2): 112-118. https://doi.org/10.11973/jxgccl201702024
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    Creep experiments were conducted on plain and double-notched specimens of P92 steel under conditions of 650℃ and 120-145 MPa. Based on Liu-Murakami and Norton-Bailey constitutive models, a modified creep constitutive model was built and verified. On this basis, the determination method of model constants was confirmed, and the creep behaviors for the plain and double-notched specimens of P92 steel were simulated. The results show that the modified model was able to simulate the three stages of creep process at 650℃ of P92 steel, and reduced the problem of mesh-sensitivity of the conventional Kachanov-Robotnov (K-R) model. The creep frature life of the double-notched specimen was longer than that of the plain specimen under the same condition, namely the notch strengthening effect. And with the increase of the notch acuity ratio, the strengthening effect became more obvious. The damage quantity had a positive correlation with the multiaxiality.