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创刊时间:1975年
主管:中华人民共和国工业和信息化部
主办:工业和信息化部电信传输研究所
主编:韩 玲
出版周期:月刊
ISSN:1008-9217
CN:11-2977/TN
邮发代号:82-949
国外代号:M1683 地址:北京市海淀区花园北路52号
电话:62300197
Email:tgzy@ritt.cn
 
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Effect of Traverse Speed on Microstructure and Properties of High-Entropy Alloy Reinforced Aluminum Matrix Composite by Friction Stir Processing
GAO Jicheng, GU Gan, ZHONG Shang, DONG Jiachen, ZHANG Sunyi
Materials For Mechanical Engineering    2021, 45 (8): 61-65,71.   DOI: 10.11973/jxgccl202108011
Abstract66)      PDF(pc) (2629KB)(0)       Save
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.
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Microstructure and Mechanical Properties of 780 MPa Dual Phase Steels with Different Chemical Composition
PAN Libo, ZHOU Wenqiang, TAN Wen, WANG Junlin, ZUO Zhijiang
Materials For Mechanical Engineering    2021, 45 (8): 45-48,54.   DOI: 10.11973/jxgccl202108008
Abstract63)      PDF(pc) (1789KB)(0)       Save
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.
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Effect of Microstructure on Surface Polishing Performance ofPrehardened 718 Plastic Mold Steel
ZHANG Le, XU Zhen, LI Zhi, CHEN Xuan, WU Xiaochun
Materials For Mechanical Engineering    2021, 45 (8): 49-54.   DOI: 10.11973/jxgccl202108009
Abstract57)      PDF(pc) (4866KB)(0)       Save
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.
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Effect of High Pressure Heat Treatment on Microstructure and Mechanical Properties of TC9 Titanium Alloy
ZHANG Dalei, LI Yuanyuan
Materials For Mechanical Engineering    2021, 45 (8): 72-76.   DOI: 10.11973/jxgccl202108013
Abstract50)      PDF(pc) (3791KB)(0)       Save
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.
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Effect of Scanning Speed on Micromorphology and Properties of 316L Stainless Steel Formed by Selective Laser Melting
ZONG Xuewen, ZHANG Jian, LU Bingheng, LI Weidong
Materials For Mechanical Engineering    2021, 45 (8): 15-19.   DOI: 10.11973/jxgccl202108003
Abstract49)      PDF(pc) (3516KB)(0)       Save
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.
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Research Status on Weldability of Duplex Stainless Steeland Corrosion Resistance of Joint
QIN Qin, TIAN Jinxin, TANG Shijia, YANG Haodong, YAN Ziyi, HUANG Taibo, LI Yunkun
Materials For Mechanical Engineering    2021, 45 (9): 13-18.   DOI: 10.11973/jxgccl202109003
Abstract47)      PDF(pc) (450KB)(0)       Save
Dual-phase stainless steel has been widely used because of its good mechanical properties and corrosion resistance, and its weldability has also become an important research object. The welding method and microstructure of the welded joint of duplex stainless steel are introduced, and pitting corrosion, stress corrosion, intergranular corrosion and the generation mechanism of embrittlement and cracks of the welded joint are discussed. Finally, the research direction of duplex stainless steel weldability is prospected.
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Effect of Postweld Heat Treatment on Microstructure and Mechanical Properties ofSIMP Steel Joint by Transient Liquid Phase Diffusion Bonding
LIU Yihui, LI Bao, CHEN Sijie, DING Guangzhu, LI Shihui
Materials For Mechanical Engineering    2021, 45 (8): 77-80,86.   DOI: 10.11973/jxgccl202108014
Abstract45)      PDF(pc) (3482KB)(0)       Save
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.
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Reason for Gracks of Inner Nozzle
GAO Yun, XIONG Yong, CHEN Changda, ZENG Houxiang
Materials For Mechanical Engineering    2021, 45 (8): 98-102.   DOI: 10.11973/jxgccl202108018
Abstract44)      PDF(pc) (5055KB)(0)       Save
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.
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Research Progress on Precious Metal Sputtering Target
XU Yanting, GUO Junmei, WANG Chuanjun, SHEN Yue, GUAN Weiming, WEN Ming
Materials For Mechanical Engineering    2021, 45 (8): 8-14,102.   DOI: 10.11973/jxgccl202108002
Abstract43)      PDF(pc) (673KB)(0)       Save
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.
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Effect of Rapid Spheroidizing Annealing on Microstructure and Hardness of SKS51 Die Steel
FENG Juning, TAN Fengliang, LI Hongjuan, ZENG Bing, WANG Li, YE Qinzheng
Materials For Mechanical Engineering    2021, 45 (8): 87-90,97.   DOI: 10.11973/jxgccl202108016
Abstract42)      PDF(pc) (4527KB)(0)       Save
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.
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