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  • ZHAO Cheng, JIANG Chunyan, ZHANG Xuewu, SHI Xiumei
    Materials For Mechanical Engineering. 2020, 44(6): 93-98.
    With the continuous development of intelligent society, piezoelectric sensors are increasingly used. The types, structures, measurement principles and application scenarios of piezoelectric sensors are described. The research progress on sensitive element materials is reviewed, and the application of high-temperature piezoelectric materials and lead-free piezoelectric materials is summarized. Finally, the future development direction of piezoelectric sensors is prospected.
  • Physical Simulation & Numerical Simulation
    DAI Xingchen, HUANG Yichang, GUAN Kaishu
    Materials For Mechanical Engineering. 2023, 47(1): 106-110.
    The thermal oxygen accelerated aging test for different times (0,168,312,408 h) of polyethylene specimen was carried out at 85℃, and the maximum load of polyethylene specimen with different aging times was obtained by indentation testing technology. The linear relationship between yield strength and maximum load was established by finite element numerical simulation, and the yield strength after aging was calculated and compared with the tensile test results. The results show that with the extension of aging time, the yield strength of polyethylene specimens obtained by tensile test gradually increased, and the maximum load obtained by indentation test also gradually increased. The linear correlation coefficient between the maximum load and yield strength of polyethylene specimen indentation test established by finite element method was 0.995, and the relative error between the yield strength of polyethylene specimen with different aging times calculated with the maximum load obtained by indentation test and the tensile test results was less than 1.5%, indicating that the indentation testing technology could accurately obtain the yield strength of polyethylene after aging.
  • ZHU Gong, YUAN Tiebing, ZHOU Li, SUN Kai
    Materials For Mechanical Engineering. 2020, 44(10): 87-91,97.
    Dynamic mechanical properties of C72900 copper alloy and 15-5PH stainless steel at different strain rates were studied by Hopkinson pressure bar test. The strain-stress curve was fitted on the basis of Johnson-Cook constitutive equation to determine material parameters. The compression test was simulated by ABAQUS software to verify the accuracy of the constitutive equation. The results show that the flow stresses of C72900 copper alloy and 15-5PH stainless steel increased significantly with increasing strain rate by tests, and both the materials had the similar flow stress behavior. The simulated true stress-true strain curves of C72900 copper alloy and 15-5PH stainless steel in the plastic deformation stage were consistent with the test results, and the relative errors were less than 3%, indicating that the established Johnson-Cook constitutive equations could describe the flow stress characteristics of C72900 copper alloy and 15-5PH stainless steel well. The application of C72900 copper alloy instead of 15-5PH stainless steel on the gasket of C919 aircraft safety pin was feasible and reliable.
  • MENG Xianming, ZHONG Zheng, CHENG Congqian, CAO Tieshan, ZHAO Jie, HUANG Yafeng, WU Yao
    Materials For Mechanical Engineering. 2020, 44(12): 85-90,96.
    The progressive failure model of fiber reinforced plastics and the continuous damage model of composite laminate of the Ls-Dyna software were applied to simulate the mechanical response and damage modes of carbon fiber reinforced plastic laminates under in-plane shear loads, with the mechanical parameters obtained by quasi-static uniaxial tensile and in-plane shear tests. The applicability of the two models was compared. The results show that in the initial linear elastic stage during in-plane shearing, the two models could simulate the mechanical characteristics of the carbon fiber reinforced plastic laminates. As the load continued to increase, the load-displacement simulation curve obtained by the progressive failure model still rose linearly, and dropped rapidly after reaching the load peak; the simulation curve had a large deviation from the test curve. When the material was damaged, because of the introduction of damage parameters, the load-displacement simulation curve obtained by the continuous damage model was nonlinear, which was in good agreement with the test curve.
  • ZHAO Yong, SU Haijun, ZHANG Jun, LIU Lin, FU Hengzhi
    Materials For Mechanical Engineering. 2021, 45(5): 1-7,44.
    Magnetic field-controlled directional solidification provides a new route to prepare high-quality alloys and castings, and is of great significance for improving the metallurgical quality of products and developing new preparation techniques. The main research progress on the directional solidification of nickel-based superalloys under magnetic field in recent years is summarized. Several typical effects between magnetic field and metal conductive melt are described. The revolution of the directional solidification structures of nickel-based superalloys under static magnetic field, alternating magnetic field, pulsed magnetic field and traveling magnetic field, and the influence of magnetic field on typical solidification defects such as stray grains and on the creep properties of superalloys are systematically summarized. The formation mechanisms of solidification structures and defects under different types of magnetic fields are discussed. Finally, the development trend and breakthrough points of directional solidification of superalloys under magnetic field are prospected.
  • LI Chenglong, LI Wenge, ZHAO Yuantao, ODHIAMBO Gerald, XIA Yu
    Materials For Mechanical Engineering. 2020, 44(5): 60-65.
    Plasma sprayed coatings have been widely used in surface protection engineering due to the excellent properties such as wear resistance, high temperature resistance and corrosion resistance. Pores are an important structural defect of plasma sprayed coatings. Excessive pores can lead to premature detachment failure of the coatings and shorten the service life, and therefore porosity is an important indicator to evaluate the coating quality. The pore formation mechanism, influencing factors, and the effect of the pores on the coating performance are briefly discribed. The research status of the porosity reduction of plasma sprayed coatings is reviewed from the aspects such as spraying process parameter optimization, laser remelting treatment, and modification of spraying materials. Moreover, the problems and development directions in the development of plasma sprayed coatings are summarized.
  • GENG Ruwei, DU Jun, WEI Zhengying
    Materials For Mechanical Engineering. 2020, 44(12): 11-17.
    The wire and arc additive manufacturing (WAAM) has gained more and more attention because of its unique advantages in forming large-scale components, and has become one of the most widely used metal additive manufacturing technology. The development history of WAAM is described. The influence of process parameters on the morphology of deposited layer and the evolution mechanism of microstructure is analyzed from the perspective of “shape and property control”. The numerical simulation methods for residual stress and their advantages and disadvantages are discussed, and it is pointed out that the combination of computational fluid dynamics and finite element method is one future research trend. The common methods for controling the residual stress and deformation, as well as the problems and challenges in wire and arc additive manufacturing, are summarized.
  • Materials For Mechanical Engineering. 2021, 45(2): 0-0.
  • ZHU Mingjun, ZHANG Ganghua, LI Shasha, ZENG Tao
    Materials For Mechanical Engineering. 2021, 45(6): 79-84,93.
    Ferroelectric materials have unique photovoltaic properties due to their polarized electric field, and are widely used in many fields, especially in photovoltaic power generation. The generation mechanism of internal electric field (photovoltaic mechanism) in ferroelectric materials, and the effects of electric field regulation mechanism on photovoltaic properties of ferroelectric materials are reviewed from aspects of the preparation of narrow band gap ferroelectric materials, enhancing visible light absorption by self-doping of oxygen deficiency constructing composite heterojunction, preparing multipole axial molecular ferroelectrics, and regulating the domain orientation and distribution in ferroelectric materials by external polarization field. The research direction of improving photovoltaic performance by regulating internal electric field is pointed out.
  • HE Yanli, LEI Liming, HOU Huipeng
    Materials For Mechanical Engineering. 2020, 44(11): 29-34.
    Powder bed fusion additive manufacturing technique can quickly form complex structural parts with high dimensional accuracy, and has received extensive attention in many fields. However, compared with traditional manufacturing methods, its cost is higher. The recycling of metal powder can effectively reduce manufacturing costs. Combined with the research progress on additive manufacturing metal powders, changes of the chemical properties, physical properties and parts properties of commonly used 316L stainless steel, Ti6Al4V alloy and IN718 alloy powders in the recycling process are summarized. On the basis of demand for additive manufacturing of civil aviation parts, several problems existing in metal powders recycling are analyzed, and solutions are proposed.
  • HE Jie, MA Shizhou, ZHANG Xinggao, GAI Xiqiang, CHEN Houhe, ZHANG Kaichuang
    Materials For Mechanical Engineering. 2020, 44(11): 46-52,58.
    Additive manufacturing is an important development direction of advanced manufacturing technique for metal parts, but the metal powder for additive manufacturing has some problems such as insufficient research and development, weak stability and incomplete standards, which seriously restrict its development. The basic principles of common spherical metal powder preparation techniques including centrifugal atomization method, two-stream atomization method and spheroidization method are summarized, and their advantages, disadvantages and development status are introduced. It is proposed that the development of domestic additive manufacturing powder preparation technique can start from two aspects. One is to carry out process and equipment improvement and standardization research on traditional methods, and build automated factories; the other is to strengthen the research on basic theories of powdering and explore new processes.
  • LIU Quansheng, FAN Mengting, LUO Xinran
    Materials For Mechanical Engineering. 2021, 45(1): 66-72,79.
    6063 aluminum alloy was prepared by pressure forming process, and then was treated by solution at 535 ℃ and aging. The effects of solution time (15-120 min), aging temperature (160-200 ℃) and aging time (1-24 h) on the microstructure, tensile properties and hardness of the aluminum alloy were studied. The results show that with increasing solution time, the grain size of 6063 aluminum alloy increased, and the primary Mg2Si phase gradually disappeard and redissolved in the matrix; but the solution time had no effect on the content and morphology of α-Al8Fe2Si phase and β-Al5FeSi phase. After solution treatment, with increasing aging temperature or aging time, the number of second phase Mg2Si increased, but a higher temperature or a longer aging time resulted in the coarse of the Mg2Si phase. With increasing solution time, aging time or aging temperature, the strength and hardness of the alloy increased first and then decreased, and the precentage elongation after fracture decreased first and then increased. The appropriate solution and aging treatment system for 6063 aluminum alloy was 535 ℃×60 min + 180 ℃×7 h; at this time the Mg2Si phase precipitated in the alloy was the smallest and dispersed, and the alloy had the highest strength and hardness and the appropriate precentage elongation after fracture.
  • CHEN Weiqing, HAN Zhiyuan, WU Jianping, CAO Luowei, LIU Wenbin
    Materials For Mechanical Engineering. 2020, 44(11): 1-6.
    Metallographic examination and tensile test were carried out on the long-term service radiation section tube of ethylene cracking furnace, and the microstructure, carbide size, room temperature and high temperature mechanical properties of carburized and non-carburized zone were studied. The quantitative relationship between carbide width and tensile properties of furnace tube was established. The results show that the grain morphology and size of non-carburized zone and carburized zone of the furnace tube were similar. The former was composed of austenite matrix, primary carbides, G phase and NbC phase; the latter had no G phase, and its primary carbides were obviously coarsened. The carburized zone had more creep holes and microcracks. The room temperature strength and plasticity of the furnace tube were seriously deteriorated. The high temperature tensile properties of the non-carburized zone basically met the requirements, and the carburized zone was obviously embrittled. The carbide width increased with the distance from outer surface of furnace tube. The tensile strength and yield strength of the furnace tube were positively related to the carbide width, and the percentage elongation after fracture was negatively related to it.
  • TAN Zhijun, GAO Shuang, HE Bo
    Materials For Mechanical Engineering. 2020, 44(9): 11-16.
    Laser additive manufacturing is an ideal advanced manufacturing technique with high efficiency and high flexibility. Materials undergo a cyclic rapid heating and cooling process during laser additive manufacturing, producing severe residual stresses in metal components and leading to unpredictable deformation problems. This has become a bottleneck to restrict the development and application of the technique. The research status of deformation of metal components during laser additive manufacturing is reviewed from aspects of formation mechanism, testing methods, influencing factors and numerical simulation. The effects of laser power, scanning speed, scanning strategy, substrate preheating and other process parameters on deformation of metal components are described in detail. The prediction and control methods of the current additive manufactured product deformation are described. The future research direction of laser additive manufacturing deformation control is prospected.
  • MA Mingtu, JIANG Songwei, LI Guangying, FENG Yi, ZHOU Jia, LU Hongzhou, LI Fuhuo
    Materials For Mechanical Engineering. 2020, 44(7): 1-7,27.
    Development in recent years of hot stamping steels, including ordinary hot stamping steel, hot stamping steel with high hardenability and oxidation resistance, high strength ductile hot stamping steel, ultra high strength hot stamping steel, high hydrogen embrittlement sensitivity hot stamping steel and ultra high strength hot stamping steel reinforced by nanoparticles, is summarized. The relation between lightweight and functionality of hot stamping steel parts, the relation between strength and hydrogen embrittlement and the influence mechanism of microstructure refinement on strength and toughness are analyzed. The suggestions for the further development direction of hot stamping steels are put forward.
  • Materials For Mechanical Engineering. 2021, 45(1): 0-0.
  • ZHANG Xin, CHEN Gang, LI Hongwei, CHEN Tong, WANG Changshun, XU Lanjun, DU Zhiming, QIN Xukun
    Materials For Mechanical Engineering. 2020, 44(10): 6-11.
    Under the background of increasing demand for lightweight, liquid die forging technique with excellent formability has been widely concerned. The lightweight design criteria and key points of lightweight design of equipments are summarized, and the application of liquid die forging aluminum alloy in equipments is introduced. The research progress on liquid die forging technique of aluminum alloy from the aspects of process principle and characteristics, forming materials, forming die and forming equipment is reviewed. Finally, the research and development direction of this technique in the future is put forward.
  • ZHANG Guoliang, LI Yuefang, LI Xiang
    Materials For Mechanical Engineering. 2021, 45(3): 66-70,97.
    Mechanical and physical parameters and curing residual strain of epoxy resin potting material with curing temperature of 60℃ were tested at environmental temperatures of -30-60℃. Taking it as an input condition, the thermal strain of the epoxy resin potting structure was simulated by the finite element simulation, and the results were compared with the test results, and the thermal coupling characteristics of the epoxy resin potting structures were studied. The results show that the relative errors of the simulated thermal strain and the experimental thermal strain of the epoxy resin potting structure were both within the allowable range of the project, the finite element simulation results was accurate. The thermal stress in the range of -30-60℃ was far less than its fracture strength, and it would not crack due to thermal stress in the range of temperature.
  • HU Rudan, SUN Jingwen, LIU Yifan, QIAN Xingyue, ZHANG Litong, ZHU Junwu
    Materials For Mechanical Engineering. 2021, 45(1): 20-27.
    The cobalt-doped manganese oxide for aqueous zinc-ion battery cathode material was prepared by solvothermal, hydrolyzing and annealing with cobalt nitrate and manganese nitrate as raw materials. The microstructure and electrochemical performance of cobalt-doped manganese oxide was investigated. The results show that the prepared cobalt-doped manganese oxide h-CoMn3.2Ox had a hierarchical yolk-shell structure, and the porous shell surface was decorated with petal-like nanosheets with radial dimension of more than 100 nm. Both of the shell and nanosheets were composed of primary nanoparticles with average size of 5 nm. Cobalt-doping endowed manganese oxides with small size and delicate structure. h-CoMn3.2Ox had the manganosite MnO crystal structure. Compared with monometallic manganese oxide, h-CoMn3.2Ox exhibited relatively large specific surface areas and specific capacities, and had good cyclic stability. The energy-storage behavior of h-CoMn3.2Ox was attributed to sequent co-insertion of H+ and Zn2+.
  • XU Wenhu, ZHANG Peilei, JIANG Qi, LIU Zhiqiang, YU Zhishui, YE Xin, WU Di, SHI Haichuan
    Materials For Mechanical Engineering. 2020, 44(10): 17-21,47.
    The thick-wall parts of Inconel 625 alloy were prepared by additive manufacturing technique using cold metal transition (CMT) arc as heat source. The microstructure and properties of the parts under oscillating and two-pass multi-layer arc trajectories were comparatively studied. The results show that spatter appeared during the additive manufacturing with oscillating arc trajectory, and the surface of the thick-wall parts was rough; no obvious spatter appeared during additive manufacturing with two-pass multi-layer arc trajectory, and the surface was smooth. The growth mode of dendritic crystals in the thick-wall parts was epitaxial growth, and there were secondary and tertiary dendrites in the dendritic crystals; the dendrite spacing under oscillating arc trajectory was smaller than that under two-pass multi-layer arc trajectory. The average tensile strength of the thick-wall parts under two-pass multi-layer arc trajectory was higher than that under oscillating arc trajectory. The anisotropy percentages of the tensile strength of thick-wall parts under oscillating and two-pass multi-layer arc trajectory were very small, which were 4% and 4.5%,respectively. The fracture type of thick-wall parts was ductile fracture.
  • WANG Xiaobo, HE Zhiyong, WANG Feng, ZHANG Qifu
    Materials For Mechanical Engineering. 2021, 45(7): 1-6,34.
    Silicon carbide ceramic has high strength and thermal conductivity, and good chemical stability, and is widely used in aerospace, petrochemical, integrated circuits and other fields; however, defects are easy to form in the silicon carbide ceramic during processing because of its high hardness and brittleness, which restricts the application of silicon carbide ceramic with complex structures. The preparation processes of silicon carbide ceramic with complex structures are described, and the advantages and disadvantages of the commonly used preparation technologies, such as cold isostatic pressing combined with pressure-free sintering, gel injection molding combined with reactive sintering, slip casting combined with reactive sintering, 3D printing combined with reactive sintering, are analyzed in order to provide a certain theoretical reference for the preparation of silicon carbide ceramic with complex structures.
  • LIU Ting, ZHAO Cheng, ZHANG Ganghua, WANG Yuanyuan
    Materials For Mechanical Engineering. 2020, 44(6): 82-87,92.
    Research progress on four piezoelectric application materials in the field of energy harvesting, including piezoelectric ceramics, multi-stacked piezoelectric ceramics, piezoelectric polymers and piezoelectric composites, is reviewed. The structural characteristics, preparation methods, and application occasions are highlighted, and the research trends of the piezoelectric materials in future is proposed.
  • LIU Yuning, WANG Yunpeng, ZHU Rufei, WANG Hu, BAI Yike, LOU Huafen
    Materials For Mechanical Engineering. 2021, 45(1): 1-7.
    Development of high speed and high performance of mechanical equipments requires higher strength and better wear resistance of wear-resistant copper alloys. Although performance of traditional aluminum bronze series, manganese brass series and lead brass series alloys has been improved, their application scope is limited by various factors, such as material characteristics, processing technology and environmental protection, respectively. The application status and research progress of five typical wear-resistant copper alloys with high application values including Cu-Ni-Sn series, Cu-Al2O3 series, Cu-Nb series, Cu-C series (including copper/graphite, copper/graphene and copper/carbon nanotubes) and complex brass are described from preparation process, properties and application field. The problems in their development and application are analyzed, and their development prospect is also discussed.
  • RAO Delin, MO Jiahao, GAO Jianbo, LI Jun, ZHANG Shuyan
    Materials For Mechanical Engineering. 2021, 45(7): 7-11.
    The evaluation of mechanical performance of reactor pressure vessel (RPV) steel is the main content of the life extension evaluation of nuclear power plants, and the increase of ductile-brittle transition temperature caused by irradiation damage is the main factor affecting operational safety and life. The toughness and brittleness transition evaluation of RPV steel is carried out by drawing surveillance samples, but the shortage of the surveillance samples forces material workers to study the toughness evaluation using small sample and sample reconstitution technique. The toughness evaluation methods of RPV steel at home and abroad in recent years are discussed, and the application of several nondestructive testing techniques on RPV steel mechanical property testing is described. The research progress on the irradiated embrittlement mechanism of RPV steels, especially the microstructure evolution mechanism of RPV steel under the high irradiation condition, in the past three years at home and abroad is described. Finally, the prospect of toughness evaluation and related mechanism research of RPV steel in China is presented.
  • PENG Dingwen, HU Menglei, LIU Haojie, JIN Jie
    Materials For Mechanical Engineering. 2021, 45(1): 50-58,65.
    The 304 stainless steel substrate was grinded to 1200# (1# process), 2000# (2# process) by sandpaper in sequence and grinded to 2000# and polished by diamond polishing paste with size of 0.5 μm (3# process), respectively, and then the CrMoN coating was deposited on the surface. The phase composition, surface and cross-section morphology, hardness, surface hydrophobicity, corrosion resistance and conductivity of the coating were studied. The results show that the roughness of the coating surface deposited on the substrate surface pretreated with 1# process was the largest, followed by that pretreated with 2# process, and the roughness that pretreated with 3# process was smallest. The phase of the coating consisted of CrN, Cr2N and Mo2N. With decreasing substrate surface roughness, the microhardness, free corrosion potential and water contact angle of the coating increased, and the corrosion current density and interface contact resistance after polarization decreased. The comprehensive properties of the CrMoN coating deposited on the substrate surface pretreated with 2# process were excellent, which were close to those pretreated with 3# process.
  • DU Miaofeng, ZHANG Peizhi, GUO Fangquan, QI Hai, HAN Weiyue, HE Chenggui
    Materials For Mechanical Engineering. 2020, 44(10): 28-32.
    Two kinds of Al2O3 powder with average grain size of 0.31, 0.77 μm (named as 1# and 2#, respectively) was molded by low solid content (volume fraction of 45%) gelcasting, and then was cold isostaticly pressed (CIP) and pressurelessly sintered to obtain Al2O3 ceramics. Effects of powder and CIP pressure on densification of Al2O3 green body and ceramics were studied. The results show that the Al2O3 powder with smaller grain size was more difficult to disperse, and required higher addition amount of polyacrylate ammonium dispersant; the obtained green body and sintered ceramics had lower relative density. With increasing CIP pressure, the relative densities of the two Al2O3 green bodies increased, and the pores decreased; the relative densities of the two sintered ceramics showed a trend of increase first, then decrease, and then being stable. When the CIP pressures were 350-400 MPa, the two ceramics had the maximum relative densities and less intercrystalline pores.
  • ZHU Dong, ZHANG Liang, WU Wenheng, LU Lin, NI Xiaoqing, SONG Jia, ZHU Wenhua, WANG Jiaqi
    Materials For Mechanical Engineering. 2020, 44(8): 1-4,9.
    Selective laser melting technique is a widely used laser additive manufacturing technology in preparation of precise and complex parts, which could realize the near net forming of complex parts. Through the forming process parameters, and solution and aging treatment methods, the research progress of microstructure and mechanical properties control of TC4 alloy formed by selective laser melting in the current stage is reviewed, and the future development direction is prospected.
  • YU Haiyan, WU Hangyu, SHI Huiru
    Materials For Mechanical Engineering. 2021, 45(4): 40-45.
    Accelerated water bath moisture absorption tests at 25 ℃ and 50 ℃ were carried out on carbon fiber reinforced polymers (CFRP) laminates, and the uniaxial tension and three-point bending tests were performed. The rule of the moisture absorption, tensile strength and bending strength varying with the moisture absorption time and the bath temperature was studied. The failure mechanism of the CFRP laminates was discussed. A residual strength model of CFRP laminates was established by fitting the experimental data. On the basis of the environmental equivalent coefficient, the hygrothermal aging life of the laminates was predicted. The results show that the average saturation moisture absorption rate of CFRP laminates at 50 ℃ was 0.77%, and was larger than 0.33% at 25 ℃. At the same moisture absorption time, the moisture absorption rate at 50 ℃ was higher than that at 25 ℃. The tensile strength and bending strength decreased by 7.4% and 17.2% after moisture absorption saturation at 50 ℃ compared with that before moisture absorption, respectively, and the decrease degree was higher than those after moisture absorption saturation at 25 ℃. The higher the bath temperature, the more serious the interface damage between CFRP laminate carbon fiber and resin, and the more obvious the cracks. The real aging life prediction method on the basis of residual strength and environmental equivalent coefficient could provide evidence for the service reliability evaluation of CFRP laminates in hygrothermal environment.
  • YANG Kang, YAN Zhaowei, LIANG Yu, WANG Ji, DING Wenxi
    Materials For Mechanical Engineering. 2021, 45(2): 85-89.
    A U-shaped thin-walled structure part model of T300 carbon fiber reinforced AG80 epoxy resin (T300/AG80) composite was established by ABAQUS finite element software. The stress and springback amount (synchronous demolding by simulation) changes during hot-press curing molding and the residual stress distribution after demolding were studied. The simulation of residual stress was verified by the small-hole test method. The results show that during the molding process, the stress and springback amount of the side wall and bottom surface of the U-shaped structure part increased with time. The stress and springback amount increased with the distance from the bottom surface or the distance from the center of symmetry. After demolding, the residual stress at the center of symmetry of the U-shaped structure part was the smallest, and the residual stress increased with the distance from the bottom surface or the distance from the center of symmetry. The greater the residual stress released before and after demolding, the greater the springback amount. The relative error between the residual stress measured by the small-hole method and the simulation was less than 10%, indicating the simulation was accurate.
  • WANG Zhengqiang, LI Wenge, DU Xu, ZHAO Yuantao
    Materials For Mechanical Engineering. 2020, 44(11): 35-40.
    Shaft parts are prone to failing such as friction, wear, corrosion and fatigue during service, which seriously affect the normal operation of construction machinery equipment. Laser cladding technique, as a common technical means for repairing and remanufacturing shaft parts, can effectively extend service lives of parts. The application of laser cladding technique in the remanufacturing of shaft parts is summarized. The influence of laser cladding process parameters (laser power, cladding speed, overlap rate and powder feeding amount) and cladding material selection on the repairing performance of shaft parts and the auxiliary application of simulation software are focused on. The development trend of laser cladding remanufacturing technique is prospected.
  • XUE Houqing, SUN Changle, JIANG Xinqi, HU Hao, YANG Jichen
    Materials For Mechanical Engineering. 2021, 45(6): 57-61,69.
    Considering the effects of coating, and the effects of tensile time, tensile rate, viscoelastic stress and reaction force on initial stress, the improved hyperelastic constitutive and viscoelastic constitutive model of thermoplastic polyurethane composite fabric and a single fiber bundle were established by tensile test. The stress-strain and stress relaxation curves during the tensile process were predicted and compared with the test results. The results show that the established hyperelastic constitive model could accurately predict the stress-strain curve of the fabric and the single fiber bundle, and the realtive errors were less than 3.5%. The viscoelastic constitutive model could accurately predict the stress relaxation curve of the fabric, and the relative error was less than 3.21%.
  • JIN Guangcan, XING Yanfeng, XU Sha
    Materials For Mechanical Engineering. 2020, 44(9): 52-55.
    The lap spot welding of 6061 aluminum alloy and DP590 galvanized steel was carried out by cold metal transfer welding (CMT) technique. The microstructure and phase composition of joint interface were studied,and the formation mechanism of intermetallic compounds was discussed. The results show that the weld of the joint was well formed. There was an intermetallic compound transition layer with a thickness of about 6 μm on the interface of welding joint, the transition layer interface near galvanized steel side was smooth, and there were a lot of columnar crystals on the interface near the melting zone side. The content of iron and aluminum elements in the transition layer was almost unchanged. The microstructure near galvanized steel side was α-Fe solid solution containing aluminum, Fe2Al5 phase was formed near melting zone side, and fine needle-like FeAl3 phase was formed in melting zone.
  • WANG Yuxing, ZHANG Xia
    Materials For Mechanical Engineering. 2021, 45(3): 41-45.
    CrAlN nano-multilayer films were prepared by magnetron sputtering technique under different bias voltages (-60,-70,-80,-90 V) of the substrate, and the effect of bias voltage of the substrate on the microstructure and mechanical properties of the film was studied. The results show that with increasing absolute value of the substrate bias voltage, the nitrogen content in the CrAlN nano-multilayer film increased, the phase composition unchanged, the preferred orientation changed from the CrN (111) crystal plane to the CrN (200) crystal plane, the pores on the film surface decreased, and the densification of microstructure was improved. When the bias voltage of the substrate was between -60 and -80 V, the bias voltage had little effect on the film deposition rate. When absolute value of the bias voltage was higher than 80 V, the deposition rate decreased significantly. With increasing absolute value of bias voltage of the substrate, the hardness and elastic modulus of the film increased, and the film base bonding force increased and then decreased, reaching the maximum at -80 V of bias voltage.
  • DONG Yikang, QI Jianjun, SUN Li, LUO Yang, WANG Jian, YANG Ting, XING Chengliang
    Materials For Mechanical Engineering. 2020, 44(10): 81-86.
    With DX56D+Z, HC220BD+Z, HC420LA and HC420/780DP automobile steel sheets as research materials, flow stresses and plastic strains obtained by uniaxial tensile testing were fitted by Ludwik, Swift, Hockett-Sherby, Voce, Swift-Hockett-Sherby and Swift-Voce hardening models, and the fitting accuracy of the six hardening models was compared and analyzed. With HC420/780DP steel sheet as an example, the fitting effect of the six hardening models was analyzed for predicting flow stresses in a large strain range (after necking).The results show that in the plastic deformation stage, the growth mode of flow stresses described by Hockett-Sherby hardening model was the closest to the test results, and the fitted flow stresses coincided with the measured results at the highest degree. The difference of flow stresses in the large strain range of HC420/780DP steel obtained by extrapolation with the six hardening models was relatively large. Swift-Hockett-Sherby and Swift-Voce mixed model had higher degrees of freedom of fitting, and had more significant fitting effect.
  • WANG Wei, SHI Jin, GENG Luyang, TANG Jianqun, GONG Jianming
    Materials For Mechanical Engineering. 2020, 44(10): 1-5,11.
    During the fire, different temperatures, fire duration and extinguishing methods, and different equipment materials result in different damage degrees and types of post-fire equipment, and changes of the microstructure and properties of equipment material. The damage evaluation method of the post-fire equipment commonly fabricated from carbon steel, low-alloyed steel and stainless steel and the research status at home and abroad of damage evaluation of mechanical properties and corrosion resistance of its material are summarized. The existing problems in the damage evaluation of the post-fire equipment and the future research direction are discussed.
  • WANG Qiang, ZHAO Yong, NI Menglong
    Materials For Mechanical Engineering. 2020, 44(7): 46-50.
    7050 aluminum alloy hole structure was strengthened by high interference fit bushing technique with single-side expansion and both-side expansion processes. The residual stress and fatigue properties of the hole structure were studied. The fatigue crack initiation life and growth life were derived quantitatively from fatigue fracture by the trapezoidal accumulation method. The results show that the residual compressive stress field with the depth of 12 mm was formed in the hole structure. The residual stress on the in-side of the single-side expansion strengthening sample was higher than that on the out-side, while the residual stresses on the in-side and out-side of the both-side expansion strengthening sample were almost the same. Compared with non-expansion strengthening sample, the average fatigue lives of single-side expansion strengthening and both-side expansion strengthening samples increased by 770% and 1 500%, respectively; the high interference fit bushing technique had obvious fatigue strengthening effects, and that of the both-side expansion strengthening process was better. The high interference fit bushing technique could both increase the fatigue growth life and initiation life of the hole structure, and the increase of initiation life was greater.
  • Review
    SUN Hui, WU Huibin, XU Yaowen
    Materials For Mechanical Engineering. 2023, 47(1): 11-18.
    High entropy alloys have great development potential in industry with the advantages of high strength,high hardness and corrosion resistance. The phases of typical high entropy alloys include solid solution phases, such as face-centered cubic (FCC) phase,body-centered cubic (BCC) phase and hexagonal close-packed (HCP) phase, and amorphous phases. The unique phase structure has an important influence on mechanical behaviors of high entropy alloys. The mechanical behaviors of high entropy alloys with different phase structures are reviewed, and the research progress on phase structure prediction methods of typical high entropy alloys, including empirical rule, CALPHAD method, first-principles calculation and machine learning method, are summarized. The future development direction of phase structure prediction of high entropy alloys is given.
  • SHI Xiumei, ZHANG Lijun, ZHENG Yangsheng, CHENG Yingye, WANG Qiang, ZHANG Le, ZHENG Shunqi, SHI Geping
    Materials For Mechanical Engineering. 2020, 44(6): 6-9,15.
    Laminated structures designed by bionics principle can better solve intrinsic brittleness problems of carbide ceramics. It is now one of the most effective ways to strengthen and toughen carbide ceramics, and has good application prospects. The structural design features of laminar ceramics are described. The preparation, performance and main toughening mechanisms of SiC and B4C laminar ceramics are reviewed. The development of carbide laminar ceramic materials is summarized and prospected.
  • JIANG Xiyi, XIA Weilong, LOU Dianjun, REN Xuepeng, SHAO Shuai, LI Haoqing, LIU Shuyu, FANG Xiaoying
    Materials For Mechanical Engineering. 2020, 44(11): 41-45.
    Ti-6Al-4V alloy was prepared by selective laser melting (SLM) technique, and the effect of laser scanning speed (705, 805, 905, 1 005, 1 105 mm·s-1) on internal defects, microstructure and mechanical properties of the alloy was studied. The results show that the pore defects and the porosity of Ti-6Al-4V alloy formed by SLM increased with the scanning speed. The alloy microstructure was composed of needle-like α' martensite, and the scanning speed had little effect on the microstructure morphology. With the increase of laser scanning speed, the tensile strength, yield strength and microhardness of the alloy decreased, and the elongation did not change much. The tensile fracture form of the alloy was ductile fracture, and there were deeper tensile cracks and more unmelted particles and spheroidization in the fracture at higher scanning speed.
  • JIAO Runnan, HUANG Haibo, LI Jinbang, PAN Luqi, DONG Jianan
    Materials For Mechanical Engineering. 2021, 45(3): 11-15.
    The effects of wear time, load, rolling speed, and relative humidity on the number of wear particles on surface of soft styrene-butadiene rubber wheel and the rubber wheel temperature were studied with a self-designed friction and wear testing machine. The wear mechanism under different working conditions was analyzed. The influence degree of each factor was analyzed by orthogonal experiment. The results show that the number of wear particles increased with the increase of wear time and load, and decreased with the increase of rolling speed and relative humidity. The number of wear particles with particle size of 2.5 μm and the temperature of the rubber wheel had the same changing trend with various factors. The amount of the small wear particles could be predicted by temperature changes. The wear mode was fatigue wear under low load, and was fatigue wear and abrasive wear under high load. The order of the influence degree of each factor was load, rolling speed, relative humidity, type of grinding wheel. When the load was 100 N, the rolling speed was 8 m·s-1, the relative humidity was 60% and the grinding wheel was a cement wheel, the number of wear particles was the least.