07 December 2021, Volume 45 Issue 11
    

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    Technical Review
  • Research Progress on Electrodeposited Nickel-Based Composite Coatings
    KAN Hongmin, MENG Yuanyuan, CUI Shiqiang, KONG Lingming, WANG Xiaoyang, LONG Haibo
    Materials For Mechanical Engineering. 2021, 45(11): 1-7. https://doi.org/10.11973/jxgccl202111001
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    Electrodeposition is the most widely used method for preparing nickel-based composite coatings at present. The characteristics of different electrodeposition methods are introduced. The effects of current density, bath pH, surfactant, content and size of second phase particles on the quality of nickel-based composite coatings are reviewed. The types and application status of nickel-based composite coatings are summarized. In the end, the future development of electrodeposited nickel-based composite coatings is prospected.
    • Testing & Research
  • Effect of Aging Treatment on Precipitation Behavior of Cu-1.9Be-0.25Co Alloy
    WANG Lei, GE Song, GUO Pengwei, KANG Junwei, ZHOU Jian, LIANG Meng, YANG Ying, ZHOU Yanjun
    Materials For Mechanical Engineering. 2021, 45(11): 8-12,23. https://doi.org/10.11973/jxgccl202111002
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    Cu-1.9Be-0.25Co alloy was treated by solid solution treatment at 780℃ for 4 h and aging treatment at different temperatures(300, 320, 340, 360℃) for different holding times(1, 2, 4, 8, 16 h). The effect of aging on the precipitation behavior of the alloy was studied. The results show that the peak aging process was 320℃×8 h, and the hardness of the alloy under this process was 422 HV. The evolution of precipitates in Cu-1.9Be-0.25Co alloy during aging at 320℃ was metastable γ' phase → semi-coherent γ' phase → non-coherent equilibrium γ phase. A large number of precipitates in the early stage of aging (1-2 h) in a short time was the main factor for the rapid increase of alloy hardness. The semi-coherent relationship between precipitates and copper matrix in the middle of aging (2-8 h) was the main reason for peak aging. At the later stage of aging (8-16 h), the precipitates separated from the semi-coherent relationship with the matrix, the alloy was over aged and the hardness decreased.
  • Microstructure and High-Temperature Electrochemical Corrosion Resistance of Magnetron Sputtered Cr-C Coating on 304 Stainless Steel Surface
    DAI Ting, REN Yanjie, DU Chenyang, CHEN Jian, ZHAO Yuhang
    Materials For Mechanical Engineering. 2021, 45(11): 13-17. https://doi.org/10.11973/jxgccl202111003
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    The Cr-C coating was deposited on the surface of 304 stainless steel current collector by magnetron sputtering technique. The microstructure, the phase composition and the electrochemical corrosion resistance in the molten sodium polysulfide at 350℃ of the coating were studied. The results show that the prepared Cr-C coating was uniform and dense, and was composed of Cr3C2, Cr7C3 and Cr phases. After corrosion in the molten sodium polysulfide for 120 h, the phases of Cr3C2、Cr7C3, NaCrS2 and Cr2S3 were formed on surface of the Cr-C coating. The Cr-C coating resistance increased with corrosion time and reached 1 454 Ω·cm2 after corrosion for 120 h, indicating that the coating could effectively inhibit the diffusion of the molten sodium polysulfide to the surface of the 304 stainless steel substrate, thereby preventing the substrate from high temperature molten-salt corrosion effectively.
  • Microstructure and Microcrack Evolution of AZ31 Magnesium AlloyDuring High Strain-rate Rolling
    XIAO Gang, WAN Quanhui, ZHU Biwu, LIU Xiao, LIU Xiaohong
    Materials For Mechanical Engineering. 2021, 45(11): 18-23. https://doi.org/10.11973/jxgccl202111004
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    The as-cast AZ31 magnesium alloy was high strain-rate (3.6-10.4 s-1) rolled at preheating temperatures of 300-450℃ and rolling linear speed of 828 mm s-1 with single pass reductions of 10%-80%, and the microstructure and mechanism of microcrack evolution were investigated. The results show that twinning was the main deformation mechanism at early deformation stage, and the twin number sharply increased; with increasing rolling reduction, recrystallization occurred and the increase of twin number was gradually stable. Twin density in magnesium alloy microstructure decreased with increasing preheating temperature. Twinning induced recystallization and bulging recrystallization were the main recrystallization of magnesium alloy. The competition among twinning, recrystallization and microcrack existed. In fine grain area, the formation of crack was attributing to the initiation, growth and coalescence of holes. Twinning induced microcracks, while the formation of many twins could inhibit the crack propagation.
  • Microscopic Failure Mechanism of Graphite in Ferrite Ductile Iron
    ZHANG Xinning, ZHANG Yingying
    Materials For Mechanical Engineering. 2021, 45(11): 24-28. https://doi.org/10.11973/jxgccl202111005
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    The failure mechanism of graphite in ferrite ductile iron under tensile and impact action was studied by in-situ microscopic observation. The influence of morphology and distribution of graphite nodules on the micro-mechanism of crack initiation and propagation was analyzed. The results show that the graphite nodules separated from the matrix when the graphite nodules uniformly distributed and the spacing was larger than the average graphite size under tensile action, and there were radial cracks in the graphite nodule or cracks throughout the whole graphite. When graphite nodules showed aggregative distribution and spacing was smaller than the average size of graphite, the cracks between the graphite nodules and the matrix connected to form larger cracks. Under impact loads, there were complementary failure mechanisms such as "onion-like" cracking and internal radial cracking in graphite nodules. Lamellar tearing was observed in irregular graphite nodules under tensile and impact loads. The rapidly closed austenite shell could keep the graphite nodule rounded and the surrounding ferrite grains evenly distributed; slow closed austenite shell resulted in graphite distortion and uneven distribution of ferrite grains.
    • Material Properties & Application
  • High-Temperature Corrosion Resistance of Laser Cladding NiCrMo AlloyCoating on 15CrMo Steel Tube Surface for Waste Incinerator
    ZHANG Kun, HUANG Can, XIONG Jiazheng, CHEN Ziming, WANG Qiusen, HUANG Man, NAN Yang, LIU Jinguo, TU Jian, ZHOU Zhiming
    Materials For Mechanical Engineering. 2021, 45(11): 29-33,37. https://doi.org/10.11973/jxgccl202111006
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    NiCrMo alloy coating was prepared on 15CrMo steel tube surface of waste incinerator by laser cladding technique. In the simulated high-temperature corrosion environment of waste incineration plant, the high-temperature corrosion resistance of coating was studied. The results show that the laser cladding NiCrMo alloy coating was uniform and dense, and metallurgical bonded with the substrate. The weight loss rate of the coating after corrosion for 72 h in the simulated high-temperature corrosion environment of waste incineration plant was 119.02 g·m-2, which was only 40% of that of the substrate, indicating that the coating had excellent high-temperature corrosion resistance which was mainly related to Cr2O3, Fe2 (MoO4) 3 and NiO oxides generated in the corrosion process.
  • Effect of TiN-Al System Binder Ratio on Properties of Polycrystalline Cubic BoronNitride Composite
    LUO Tao, JIANG Wenqing, XU Min
    Materials For Mechanical Engineering. 2021, 45(11): 34-37. https://doi.org/10.11973/jxgccl202111007
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    Taking cubic boron nitride (cBN), TiN, and aluminum as raw materials, polycrystalline cubic boron nitride (PcBN) composites by sintering at 1 500℃ and 5.5 GPa. The effect of the mass ratio (21:4,17:8,13:12,9:16) of TiN to Al in the TiN-Al system binder on the phase composition, microstructure, hardness and wear resistance of PcBN composites was studied. The results show that PcBN composite was mainly composed of BN, TiB2, TiN, AlN and Al2O3 phases. With increasing the aluminum content in the binder, the structure of PcBN composite became denser, and the porosity decreased; the hardness and wear ratio first increased and then decreased. When the mass ratio of TiN to Al was 17:8, the comprehensive property was the best with the largest hardness and wear ratio of 35.8 GPa and 7 500, respectively, and the relatively small porosity of 0.83%.
  • Microstructure and Tensile Properties of Advanced Cold Metal Transfer Welded Joint of 5A06 Aluminum Alloy Ultrathin Plates
    ZHAO Huihui, JIA Hongde, HU Lan, LI Ying, ZHOU Jiafen
    Materials For Mechanical Engineering. 2021, 45(11): 38-42. https://doi.org/10.11973/jxgccl202111008
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    Aluminum alloy 5A06 ultrathin plates with thickness of 0.8 mm were welded by advanced cold metal transfer welding process, and the forming quality, microstructure and tensile properties of the welded joint were studied. The results show that the weld was well formed, continuous and beautiful, without defects such as porosity, crack and inclusion when the front shielding gas flow rate was 20 L·min-1, the back shielding gas flow rate was 5 L·min-1, the welding current was 75-80 A, and the welding speed was 1 000 mm·min-1. The microstructure of the base metal of the joint was composed of rolled elongated α-Al phase and dispersion strengthening phase distributed at the grain boundary; the microstructure of fusion line, heat affected zone and weld was equiaxed grains. The joints fractured at the base metal after tension. The tensile strength was about 360 MPa, and the elongation percentage after fracture was about 12%, indicating the joint had excellent tensile properties. There were a lot of dimples in the fracture, and ductile fracture occurred in the joint.
  • Microstructure and Properties of Intermittent Vacuum Nitrided Layer on TB8 Titanium Alloy Surface
    FENG Yong, YANG Chuang, YAN Li
    Materials For Mechanical Engineering. 2021, 45(11): 43-46,90. https://doi.org/10.11973/jxgccl202111009
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    TB8 titanium alloy was treated by intermittent vacuum nitriding at 800℃ for 6 h, and microstructure, hardness, wear and corrosion resistance of surface nitriding layer were studied. The results show that the surface inter mittent vacuum nitrided layer of TB8 titanium alloy was mainly composed of nitride layer with thickness of 60-80 μm and nitrogen diffusion zone with thickness of 110-130 μm, and the phases of surface layer were mainly composed of TiN, TiN0.3, Ti2AlN and α-Ti. The surface layer hardness reached 800-850 HV and decrease slowly from the surface layer to the center, and the center matrix hardness was 250-270 HV. Under the same condition, the wear loss weight of alloy treated by intermittent vacuum nitriding was only 1/12 of that of the untreated alloy, shallow and narrow wear traces were formed on the surface, and the wear resistance significantly increased. The corrosion rate of alloy treated by intermittent vacuum nitriding in mixture of HF and HNO3 was about 1/153 of that of the untreated alloy, the obvious corrosion pit was not found on the surface, and the corrosion resistance greatly increased.
    • Physical Simulation & Numerical Simulation
  • Improved Critical Plane Model for Multiaxial Fatigue Life Prediction of HRB335 Steel
    QIN Shenghuan, ZHAO Gang, SHUAI Tao, ZHANG Keshi
    Materials For Mechanical Engineering. 2021, 45(11): 47-54,61. https://doi.org/10.11973/jxgccl202111010
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    Uniaxial (tension-compression and torsion paths) and nonproportional multiaxial (circular, rhombic and butterfly paths) loading fatigue tests were carried out on HRB335 steel. On the basis of the tests, the parameters of equivalent strain method, KBM critical plane model and critical plane model with stretching factor (stretching factor model) were calibrated, and the effectiveness of each model for multiaxial fatigue life prediction of HRB335 steel was compared and analyzed. The stretching factor was improved by introducing path nonproportionality and a material additional strengthening parameter, and the prediction of the improved stretching factor model was verified. The results show that the fatigue life prediction of HRB335 steel by the equivalent strain method was mostly out of the triple error range. The fatigue life prediction by the KBM critical plane model and stretching factor model under circular and butterfly path loading partly exceeded the triple error range. The fatigue life prediction of HRB335 steel under five loading paths by the improved stretching factor model was all in the triple error range, and the multiaxial fatigue life prediction of Q235 steel and 304 stainless steel was also consistent with the test results, indicating the model was reasonable and effective.
  • Shear Mechanical Characteristics and Density Dependence ofAnnular Metal Rubber Damper
    REN Zilin, ZHAO Xu, XUE Xin, BAI Hongbai
    Materials For Mechanical Engineering. 2021, 45(11): 55-61. https://doi.org/10.11973/jxgccl202111011
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    The movement characteristics of curved beam of annular metal rubber damper under the tangential and axial shear were analyzed by LS-DYNA software based on the fabrication process, shear test machining design, damping energy characterization methods of annular metal rubber damper, and simplified the three-dimensional numerical model. The shear mechanical characteristics and density dependence of annular metal rubber damper were studied. The results show that sliding mode among most of wire curved beams was parallel slipping in the metal rubber damper. With increasing density, the energy dissipation coefficient of annular metal rubber damper in tangential and axial shear increased first and then decreased, and the equivalent stiffness increased.
  • Finite Element Simulation on Fatigue Properties of S500MC HighStrength Steel Automobile Rim by Hydroforming
    YUE Fengli, REN Shijie, XU Yong, CHEN Weijin, ZHANG Shihong, ZOU Lichun, SHAO Yunkai
    Materials For Mechanical Engineering. 2021, 45(11): 62-67,75. https://doi.org/10.11973/jxgccl202111012
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    With 2.0 mm thick S500MC microalloyed high strength steel plate as raw material, an automobile rim was manufactured by hydroforming process. The fatigue properties of the rim were analyzed by finite element method, and were compared with those of conventional rolling formed SPFH540 medium strength low alloy steel rim with uniform wall thickness of 2.3 mm and S500MC microalloyed high strength steel rim with uniform wall thickness of 2.0 mm. The results show that the maximum reduction rate of wall thickness of hydroformed rim was 10.9%. The change trend of section bending stress and radial stress of the hydroformed rim was consistent with those of the two rolling formed rims, indicating that the local thinning of the rim did not significantly change the stress of the rim. The maximum bending stress and radial stress of the hydroformed rim were lower than the yield strength of the steel, the maximum bending strain and radial strain were far less than the yield strain, and the fatigue property safety factor was greater than 1, indicating that the local thinning of wall thickness would not affect the bending and radial fatigue properties of the rim.
    • Failure Analysis
  • Cause of Cracks in Automatic Welding Butt Girth Weld of X80M Steel Spiral Submerged Arc Welded Pipe
    LI Liang, HUANG Lei, LIU Long, FENG Zhenjun, XU Yan, BAI Qiang, NIE Xianghui
    Materials For Mechanical Engineering. 2021, 45(11): 68-75. https://doi.org/10.11973/jxgccl202111013
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    By the analysis of the chemical composition, mechanical properties, microstructure and fracture morphology of the automatic welding butt girth weld of two X80M steel spiral submerged arc welded pipes in a natural gas transmission pipeline, the causes of buried cracks in the girth weld were discussed. The results show that the cracks in the girth welds were located at the fusion line of the groove on the left and right sides of the filler weld. During filler welding, the contact between the copper contact tube and the weld groove led to short circuit; the high temperature generated by the short-circuit current resulted in the melting of the contact part between the contact tube and the groove; the metal copper fused at the groove was fused into the filler metal of the girth weld with the welding wire, and diffused along the base metal and weld grain boundary to form a copper enrichment zone, which finally led to the molten copper cracking of the girth weld.
    • Special Reports (Additive Manufacturing)
  • Research Progress on Main Preparation Technologies ofSpherical Metal Powder for Additive Manufacturing
    WU Wenheng, WANG Tao, FANG Ding
    Materials For Mechanical Engineering. 2021, 45(11): 76-83. https://doi.org/10.11973/jxgccl202111014
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    As a main raw material for metal additive manufacturing, spherical metal powder characteristics play an important role in the performance of additive manufacturing parts. The efficient preparation of high-quality spherical metal powder has become an important development direction to promote the upgrading of additive manufacturing technologies and industrial applications. The main preparation methods of spherical metal powder including gas atomization, plasma rotating electrode atomization and plasma atomization are introduced. The technical principle and the influence of important process parameters on powder characteristics are discussed, and the future development direction of these three types of technologies is prospected.
  • Microstructure Evolution Behavior of Laser Melting Deposited TA15 Alloy During High Temperature In-situ Tension
    CHAI Ruxia, Lü Junxia, XIE Qiang, RIZWAN Muhammad, ZHANG Yuefei, ZHANG Ze
    Materials For Mechanical Engineering. 2021, 45(11): 84-90. https://doi.org/10.11973/jxgccl202111015
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    In-situ tensile tests at 300℃ of laser melting deposited (LMD) TA15 alloy were carried out by in-situ high temperature scanning electron microscopy-electron backscattering diffraction (SEM-EBSD) mircotensile system. The microstructure evolution and fracture mechanism of the alloy during in-situ tension were studied. The results show that slip was the main plastic deformation mechanism in the LMD TA15 alloy during tension at high temperature. The crack propagation path was consistent with the slip band propagation path, and both propagated by cutting through the α strip cluster. The fracture of the alloy presented the brittle-ductile mixed fracture mode, and the existence of β grain boundaries was the root cause of local brittle fracture. In the early stage of deformation, grains rotated, and uniform plastic deformation of the alloy occurred. With increasing strain, there were a lot of low-angle grain boundaries in local grain by dislocation, and the fraction of low-angle grain boundaries increased from 4.9% before tension to 33.7% at the strain of 12%; inhomogeneous deformation of the alloy occurred.
  • Research Progress on High Cycle Fatigue Performance ofSelective Laser Melting Formed Al-Si Alloy
    ZOU Tianchun, CHEN Minying, ZHU He
    Materials For Mechanical Engineering. 2021, 45(11): 91-96,102. https://doi.org/10.11973/jxgccl202111016
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    Selective laser melting (SLM) has been one of the fastest growing additive manufacturing technologies in recent years, and is widely used in aerospace, automotive, medical and other fields. However, aluminum alloy powder has the characteristics of poor fluidity, high laser reflectivity and high thermal conductivity, resulting in rough surface of SLM forming parts and easy to form defects, which affects its fatigue properties. Based on the research status of high cycle fatigue performance of SLM Al-Si alloy at home and abroad, the influence of forming direction, forming parameters, heat treatment and surface treatment on high cycle fatigue performance and high cycle fatigue fracture mechanism are introduced, the methods of improving fatigue performance are summarized, and the research focus of SLM Al-Si alloy fatigue performance in future is prospected.
  • Research Status on Pore in Aluminum Alloy Parts by Wireand Arc Additive Manufacturing
    NIE Wenzhong, ZENG Jiayi, LI Xiaoxuan, QIU Weihao
    Materials For Mechanical Engineering. 2021, 45(11): 97-102. https://doi.org/10.11973/jxgccl202111017
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    The stress concentration generated by the pores in aluminum alloy by wire and arc additive manufacturing leads to the initiation and propagation of initial cracks, resulting in the deterioration of mechanical properties. The porosity formation cause of aluminum alloy parts by wire and arc additive manufacturing is introduced. The effects of shielding gas, welding speed, wire feeding speed, metal wire material, heat input, rolling and heat treatment on porosity are described. The future research direction of reducing porosity in aluminum alloy parts by wire and arc additive manufacturing is prospected.
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