20 August 2021, Volume 45 Issue 8
    

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  • TAN Huancheng, QIN Wenyuan, LIU Shengwang, LIU Wen, CHEN Lulu, WANG Zhenxin
    Materials For Mechanical Engineering. 2021, 45(8): 1-7. https://doi.org/10.11973/jxgccl202108001
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    3D braided composites have a spatial network structure formed by continuous fiber bundles inside; therefore 3D braided composites have higher interlayer strength than traditional laminated composites, and have higher impact resistance and crack propagation resistance than metal materials. The meso-scale geometrical modeling methods of 3D braided composites are described in detail. The research progress on dynamic tensile and compression properties, dynamic failure criteria and high-speed impact properties of 3D braided composites is reviewed. The future research direction in meso-scale geometrical modeling and dynamic tensile testing of 3D braided composites is pointed out.
  • XU Yanting, GUO Junmei, WANG Chuanjun, SHEN Yue, GUAN Weiming, WEN Ming
    Materials For Mechanical Engineering. 2021, 45(8): 8-14,102. https://doi.org/10.11973/jxgccl202108002
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    Sputtering targets are the key raw materials for the preparation of thin films by magnetron sputtering, and their quality determines the performance of the sputtered thin films. Precious metal sputtering targets are widely used in the preparation of high-performance thin films because of their excellent physical and chemical properties. The research progress on the preparation methods, technical requirements and application of precious metal sputtering targets is reviewed. The development direction of high purity, large size, high utilization rate, and integrated development of target production and sputtering film is put forward.
  • ZONG Xuewen, ZHANG Jian, LU Bingheng, LI Weidong
    Materials For Mechanical Engineering. 2021, 45(8): 15-19. https://doi.org/10.11973/jxgccl202108003
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    316L stainless steel specimens were prepared by selective laser melting (SLM) at different scanning speeds (700-1 200 mm·s-1). The influence of the scanning speed on the micromorphology and mechanical properties was studied. The results show that with the increase of the scanning speed, the surface roughness and the internal voids of the specimen increased in number; the tensile strength, percentage elongation after fracture, and hardness of the specimen first slowly increased, and then rapidly decreased when the scanning speed was greater than 1 000 mm·s-1, while the yield strength showed a decreasing trend. With increasing scanning speed, the impact absorption energy of the specimen first remained stable and then decreased, the number of holes and cracks near the impact fracture gradually increased, and the impact fracture form changed from ductile-brittle fracture to brittle fracture. When the scanning speed was 700-800 mm·s-1, the impact toughness of the specimen was the best, whose impact absorption energy was 58.6-60.0 J.
  • YAN Minjie, MENG Kaiyue, WU Zhijie, ZHOU Yadong, YANG Weichao
    Materials For Mechanical Engineering. 2021, 45(8): 20-24,31. https://doi.org/10.11973/jxgccl202108004
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    Composite lithium-based magnetorheological greases, containing 30wt%, 45wt%, 60wt% ferromagnetic particles, respectively, were prepared by using PAO40 poly-alpha olefin synthetic base oil, thickening agents of dodecyl hydroxyl stearic acid, sebacic acid, boric acid and lithium hydroxide, and FeSiB soft magnetic powder. The rheological property and magnetorheological effect of the magnetorheological greases were studied. The results show that the shear stresses of the three magnetorheological greases increased with increasing shear rate, and increased rapidly and then tended to be stable with increasing current. The storage modulus decrased rapidly and then tended to be stable with increasing shear rate, and increased first and then tended to be stable with increasing current. With increasing current, the loss factor of the magnetorheological grease increased first, then decreased and then tended to be stable, the damping characteristics and the magnetorheological effect were improved. The higher the ferromagnetic particle content, the larger the shear stress and the storage modulus of the magnetorheological grease, and the stronger the damping characteristics and the magnetorheological effect.
  • ZHENG Jun, YOU Xiaogang, TAN Yi, ZHAO Longhai, LIAO Jiao
    Materials For Mechanical Engineering. 2021, 45(8): 25-31. https://doi.org/10.11973/jxgccl202108005
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    The electron beam refining technique was used to refine Ti3Ni alloy. The removal mechanism of TiO2 and TiN inclusions in Ti3Ni alloy was studied. The results show that under the refining conditions, the temperature at the melt center was the highest, was 2 681.2 K, which was much higher than the melting point of TiO2. The TiO2 inclusions on the melt surface and near the surface were mainly removed by disslution. Under the refining conditions, the lowest disslution temperature of TiN inclusions was 2 671.5 K, which was slightly lower than the temperature at the melt center, and the lowest decomposition temperature of TiN was 1 869.6 K, which was far lower than the temperature at the melt center. The TiN inclusions on the melt surface and near the surface could be removed by disslution and decomposition.
  • YOU Yaying, CHEN Feng, QIAN Junchao, GOU Haodong, CHEN Zhigang
    Materials For Mechanical Engineering. 2021, 45(8): 32-36,44. https://doi.org/10.11973/jxgccl202108006
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    A SiO2-CuO composite fiber material was prepared by electrospinning combined with high temperature calcination with polyvinylpyrrolidone as a template under the condition of the molar ratios of anhydrous copper acetate (copper source) to tetraethyl orthosilicate of 1:10, 1:20, 1:40. The microstructure, air permeability and antibacterial property of the composite fiber material were studied. The results show that the SiO2-CuO composite fiber material was successfully prepared by the electrospinning method combined with calcination at 600 ℃. CuO nanoparticles uniformly distributed in the SiO2 fibers, which belonged to monoclinic crystal system. With increasing anhydrous copper acetate content, the crystallization degree of the CuO particles increased. The water vapor transmission of the composite fiber material was 2 994.4-4 017.6 g·m-2·d-1, which was about 60% of that under the condition of non-material covering, indicating that the composite fiber material had good air permeability. With increasing anhydrous copper acetate content, the antibacterial rate of composite fiber materials increased, indicating that the antibacterial property was improved. When the molar ratio of anhydrous copper acetate to tetraethyl orthosilicate was 1:10, the composite fiber material had good air permeability and a high antibacterial rate of 99.9%.
  • ZOU Jie, PENG Wenfei, CHEN Zhenyang
    Materials For Mechanical Engineering. 2021, 45(8): 37-44. https://doi.org/10.11973/jxgccl202108007
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    Hot compression tests were conducted on 2219 aluminum alloy at deformation temperatures of 330-450 ℃, strain rates of 10-2-10 s-1, and compression deformation of 60% on a Gleeble-3500 thermal simulation machine, and the dynamic recrystallization behavior during hot deformation was studied. Through analysis and fitting of the experimental data, the thermal deformation characteristic parameter model based on the Z parameter, the dynamic recrystallization kinetic model based on the improved Avrami equation, and the dynamic recrystallized grain size model based on deformation temperatures and strain rates were established. The results show that at a low strain rate and a high deformation temperature, 2219 aluminum alloy was more prone to dynamic recrystallization. According to the dynamic recrystallization kinetic model, the optimal hot working conditions were determined as a strain rate of 0.1 s-1 and a temperature of 360 ℃. Under this condition, the dynamic recrystallization degree of 2219 aluminum alloy was the highest. The prediction accuracy of the dynamic recrystallized grain size model was high, and the linear correlation coefficient reached 0.95.
  • PAN Libo, ZHOU Wenqiang, TAN Wen, WANG Junlin, ZUO Zhijiang
    Materials For Mechanical Engineering. 2021, 45(8): 45-48,54. https://doi.org/10.11973/jxgccl202108008
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    780 MPa dual phase steels with two kinds of composition were produced under the same manufacturing condition; one had high carbon conent (carbon mass fraction of 0.157%, high-C series), and the other had low carbon content and was added with Nb and Mo elements (Nb-Mo series). The microstructure, tensile properties, hole expansion performance and nanoindentation hardness of hard and soft phases of the two steels were studied and compared. The results show that the microstructures of the two steels consisted of ferrite and martensite. Compared with those of the high-C series test steel, the ferrite grains of the Nb-Mo series test steel were refined, the yield strength and yield ratio were improved, and the hole expansion rate was higher. Due to the higher carbon content, the martensite in the high-C series test steel had relatively high hardness, and the hardness distribution was ralatively divergent. The hardness distribution of the martensite in the Nb-Mo series test steel was concentrated. The nanoindentation hardness difference between the ferrite and the martensite in the Nb-Mo series test steel was smaller, so the hole expansion performance was better.
  • ZHANG Le, XU Zhen, LI Zhi, CHEN Xuan, WU Xiaochun
    Materials For Mechanical Engineering. 2021, 45(8): 49-54. https://doi.org/10.11973/jxgccl202108009
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    Samples at different positions of prehardened large section 718 plastic mold steel were heat treated, and then mechanically polished and manually polished. The surface roughness was tested. The effect of microstructure on the surface polishing performance was studied. The results show that after heat treatment, the sample with the original microstructure of non-uniform granular bainite had the worst uniformity of microstructure and hardness distribution, leading to the largest surface roughness and the worst polishing performance after polishing. The sample with the original microstructure of uniform granular bainite after heat treatment had the best uniformity of microstructure, and the hardness was relatively large and distributed uniformly; therefore the surface roughness after polishing was the smallest. Moreover, no orange lines or pitting defects appeared on the surface after engineering polishing (professional manual polishing for engineering applications), and the limit of surface roughness reached 0.019 μm; the surface quality met the application requirements of high-end plastic mold steel. The uniform distribution of carbides in the sample with the original microstructure of tempered martensite after heat treatment made the surface polishing performance slightly better than that of the lower bainite sample.
  • GUO Xiaoqiang, LIU Jun, HUANG Liang, FANG Dake, WEI Anchao, WANG Guorong
    Materials For Mechanical Engineering. 2021, 45(8): 55-60. https://doi.org/10.11973/jxgccl202108010
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    The reciprocating wear test of 13Cr-L80 steel tubing and casing was carried out with a reciprocating friction and wear testing machine. The effects of contact load (50,100,150,200,250 N), reciprocating stroke (2,4,6,8,10 mm), reciprocating frequency (0.6, 0.9, 1.2, 1.5 1.8 Hz) and completion fluid density (1.0, 1.1, 1.2, 1.3, 1.4 g·cm-3) on the wear performance of the tubing were studied. The results show that with increasing contact load, reciprocating frequency and reciprocating stroke, the wear amount of the tubing increased, and the friction factor and wear rate changed little. With increasing completion fluid density, the wear amount and wear rate of the tubing decreased, and the friction factor decreased first, and then tended to be stable when the completion fluid density increased to 1.2 g ·cm-3. Under testing conditions, with increasing contact load, reciprocating frequency and completion fluid density, the wear mode of the tubing changed from the abrasive wear to the adhesive wear, and the wear modes of the tubing under different reciprocating stroke were all adhesive wear.
  • GAO Jicheng, GU Gan, ZHONG Shang, DONG Jiachen, ZHANG Sunyi
    Materials For Mechanical Engineering. 2021, 45(8): 61-65,71. https://doi.org/10.11973/jxgccl202108011
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    AA5083 aluminum matrix composite reinforced by FeCoNiCrAl high-entropy alloy particles were prepared by friction stir processing. The effect of the traverse speeds (45,60,75 mm·min-1) on the high-entropy alloy particle distribution, microhardness and wear resistance of the composite was studied. The results show that no new phases were formed in the prepared composite. The microhardness of the composite was higher than that of the aluminum alloy matrix. With the increase of the traverse speed, the distribution uniformity of the high-entropy alloy particles became worse and the microhardness of the composite decreased slightly. The average friction coefficient and wear rate of the composite were lower than those of the aluminum alloy matrix. With the increase of the traverse speed, the friction coefficient and wear rate of the composite increased, and the wear resistance decreased. The wear mechanisms of the composite and aluminum alloy were abrasive wear and adhesive wear, respectively.
  • ZHANG Min, DU Mingke, ZHANG Yunlong, WANG Gang, ZHU Ziyue
    Materials For Mechanical Engineering. 2021, 45(8): 66-71. https://doi.org/10.11973/jxgccl202108012
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    Q345B low carbon steel and 20Mn23Al non-magnetic steel were welded by gas metal arc welding with E316LT0-1 stainless steel welding wire. The microstructure and mechanical properties of the welded joint were studied. The results show that the microstructure of the filling weld layer consisted of skeletal δ ferrite and austenite, and that of the backing weld layer was composed of dendritic ferrite and austenite. The microstructure of the overheated coarse-grained zone on the Q345B steel side consisted of bainite and Widmanstaten structure, and that of the phase transformation recrystallization zone consisted of pearlite and ferrite. The heat-affected zone on the 20Mn23Al steel side had a microstrucrture of twin austenite and a small amount of ferrite. The interdiffusion of alloying elements in the base metals and weld occured, and the diffusion layer thicknesses on the Q345B steel side and 20Mn23Al steel side were about 15, 25 μm, respectively. The tensile property of the joint was better than that of the Q345B steel while worse than that of the 20Mn23Al steel. The weld of the joint had the largest hardness, followed by the heat-affected zone.
  • ZHANG Dalei, LI Yuanyuan
    Materials For Mechanical Engineering. 2021, 45(8): 72-76. https://doi.org/10.11973/jxgccl202108013
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    High pressure heat treatments at temperatures of 920-980 ℃ and pressures of 1-6 GPa were conducted on TC9 titanium alloy. The microstructure, hardness, compressive strength and plastic deformation resistance of the alloy after high pressure heat treatments were studied and were compared with those after normal pressure annealing at 950 ℃. The results show that the α phase in the microstructure of the TC9 titanium alloy was significantly refined after high pressure heat treatment compared with that after normal pressure annealing at 950 ℃, and was the smallest in size at temperature of 950 ℃ and pressure of 3 GPa. After heat treatment at 950 ℃ and a pressure of 3 GPa, the small blocky α phase and fine needle-shaped α' martensite were formed in the titanium alloy. Moreover, the hardness and the compressive strength at room tempearature and at 500 ℃ of the alloy increased by 12.95%, 7.33% and 8.89% those after normal pressure annealing at 950 ℃, respectively, and the plastic deformation resistance was improved.
  • LIU Yihui, LI Bao, CHEN Sijie, DING Guangzhu, LI Shihui
    Materials For Mechanical Engineering. 2021, 45(8): 77-80,86. https://doi.org/10.11973/jxgccl202108014
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    SIMP steel tubes were subjected to transient liquid phase (TLP) diffusion bonding with different isothermal solidification parameters, and then subjected to 1 060 ℃×4 min in-situ normalizing and (780±3)℃×120 min tempering treatment. The microstructure and mechanical properties of the joints before and after heat treatment were studied and compared. The results show that the microstructure of the heat-affected zone of the joint consisted of coarse martensite and retained austenite, and the martensite transformed into fine and uniform tempered martensite after postweld heat treatment. The weld interface changed from a straight line to a curved line after postweld heat treatment, and the interface bonding area increased. After the postweld heat treatment, the tensile strength and microhardness of the joint were slightly reduced, but the tensile strength was still above 700 MPa; the impact absorption energy increased from no more than 9.4 J to more than 40 J; the form of tensile fracture changed from brittle fracture to ductile fracture. The joint after heat treatment had relatively good comprehensive mechanical properties.
  • YU Fengyun, LIU Hao, DU Yanfeng
    Materials For Mechanical Engineering. 2021, 45(8): 81-86. https://doi.org/10.11973/jxgccl202108015
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    Sn-3.0Ag-0.5Cu solder balls with diameters of 200, 300,400 μm were reflowed on electroless nickel electroless palladium immersion gold (ENEPIG) pads for 1, 3, 5 and 7 times to form Sn-3.0Ag-0.5Cu/ENEPIG solder joints. The solder joints after 3-time reflow were subjected to aging treatment at different temperatures (75,100,125 ℃). The effect of the solder ball size on the interface microstructure and shear strength of the solder joints after reflow and aging was investigated. The results show that after reflow and aging treatment, the thickness of the interfacial intermetallic compound and the shear strength of the solder joints decreased with increasing solder ball diameter, showing obvious size effect. When the size of solder ball was the same, the increase of reflow time and aging temperature led to the increase of interfacial intermetallic compound thickness and the decrease of the shear strength of the solder joint.
  • FENG Juning, TAN Fengliang, LI Hongjuan, ZENG Bing, WANG Li, YE Qinzheng
    Materials For Mechanical Engineering. 2021, 45(8): 87-90,97. https://doi.org/10.11973/jxgccl202108016
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    The SKS51 steel was subjected to rapid spheroidizing annealing treatment (including two stages of austenitizing and isothermal spheroidizing) based on the principle of divorced eutectoid transformation. The effects of the austenitizing temperature (750, 780 ℃), austenitizing holding time (10, 20 min) and isothermal spheroidizing temperature (650, 680, 700 ℃) on the microstructure and hardness were studied. The results show that under the test conditions, by increasing the austenitizing temperature or prolonging the austenitizing holding time, the flaky carbides in the steel increased in number, the spheroidizing effect became deteriorating, and the hardness increased. After austenitizing at 750 ℃ for 10 min, with the increase of the isothermal spheroidizing temperature, the content and size of spherical carbides in the SKS51 steel increased, and the hardness decreased. After 750 ℃×10 min+700 ℃×2 h rapid spheroidizing annealing, the SKS51 steel had the largest number of spherical carbides and the lowest hardness.
  • ZHOU Liming, WU Mingxia, LIAO Fuqiang, XIONG Ji, LI Yanbo, ZHANG Zhiyin
    Materials For Mechanical Engineering. 2021, 45(8): 91-97. https://doi.org/10.11973/jxgccl202108017
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    Effects of the compositional exponent and the gradient self-lubricating layer thickness (layer thickness) on the residual stress of the graphite /Ti(C,N)-based cermet gradient self-lubricating composite were studied by finite element method. The gradient self-lubricating composite was prepared by layer-sintering method. The surface residual stress was measured by X-ray diffraction and compared with the simulation. The results show that the radial compressive stress mainly distributed in surface of the gradient self-lubricating layer, and there was serious stress concentration at the interface edge between the cermet matrix and the gradient self-lubricating layer. With increasing compositional exponent, the surface radial compressive stress increased, and the stress at the interface decreased. Increasing the layer thickness could improve the stress distribution at the interface, but the surface radial compressive stress decreased. The optimal compositional exponent was 1.0-2.0, and the layer thickness was 1.0-1.5 mm. The change of the residual compressive stress with the layer thickness by testing was consistent with the simulation.
  • GAO Yun, XIONG Yong, CHEN Changda, ZENG Houxiang
    Materials For Mechanical Engineering. 2021, 45(8): 98-102. https://doi.org/10.11973/jxgccl202108018
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    Cracks appeared in the heat affected zone of the surface tack welding spot and roll welding spot of a GH536 alloyed inner nozzle of a certain aircraft after working for 22 h. The reason for cracks was analyzed by fracture morphology and microstructure observation and chemical composition test. The results show that the cracks on the inner nozzle were fatigue cracks initiated under a relatively large stress and propagated under a relatively small stress. The argon arc welding positioning did not meet the process requirements of the inner nozzle, and the tack welding spots were not removed. During the fatigue loading, there was stress concentration in the heat affected zone of the tack welding spot and the subsequent roll welding spot, leading to initiation of fatigue cracks.