31 December 2017, Volume 41 Issue Z2
    

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  • Microstructure and Mechanical Properties of Large Size of Hot Work Die Steel H13
    LIN Peng, MA Dangshen, CHI Hongxiao, ZHOU Jian
    Materials For Mechanical Engineering. 2017, 41(Z2): 1-5,8.
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    By using OM、SEM、EDS、impact and tensile testing machine, microstructure and mechanical properties of large size of H13 steel forging piece were studied. The results were that because of "size effect",H13 steel of large size had severer carbon segregation,even with massive white ferrite massive region existed;eutectic carbide was V-riched MC type carbide,and at 1/2R position,the size of eutectic carbide was largest,which was likely related with solidification characteristics of large size electroslag ingot;impact toughness at center area was low and the fracture surfaces were tear ridge and quasi cleavage fracture surface,belonging to brittle fracture,plasticity increased from center to edge area and at 1/2R area,because of large size of eutectic carbide,plasticity had trough value.
  • Production Process Optimization of Large-section Forged Bars of High Speed Steel
    YANG Tianliang, GU Rong, KANG Aijun, LIU Yufen, GUO Qiang
    Materials For Mechanical Engineering. 2017, 41(Z2): 6-8.
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    The production process of large-section forged bars of high speed steel was optimized with the existing open die forging press. Special FM forging method was used to avoid tensile stress generating in the center of large forged bars, thus preventing internal longitudinal cracks caused by carbides.
  • The Role of Si in the Semi-High-Speed Steel HYRH12
    ZHANG Zhanpu, NIU Xufei, CHI Hongxiao, MA Dangshen, HE Ning
    Materials For Mechanical Engineering. 2017, 41(Z2): 9-14.
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    The effect of different Si contents on metallurgical quality and heat treatment properties of HYRH12 steels were studied. The results show that, Si can significantly promote carbide precipitation and significantly increase the hardness. The 0.7wt% Si steel has the worst toughness and strength, and the 0.3wt% Si steel has the best impact toughness and bending strength. The physical properties, heat treatment process and performance date were also given in this paper.
  • Machinability of a New Free-cutting and Non-magnetic Die Steel
    XUE Chun, GAO Yushun, HUANG Chunbo, WANG Wenzheng
    Materials For Mechanical Engineering. 2017, 41(Z2): 15-17,22.
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    Hardness, relative permeability were tested on a new free-cutting and non-magnetic die steel YW and contractive material steel A50 after heat treatment. The wear loss of the cutting tools used for machining the steel YW and steel A50 was measured at the same cutting conditions so that the machinability of the steels were studied. Results show that the hardness of steel YW after solution and aging treatment was 42-43 HRC. The relative permeability was 1.005-1.019. The steel YW wasnon-magnetical and high hardness. Contractive steel A50, the wear loss of cutting tool machining steel YW was less over 30 percentage than that of cutting tool machining steel A50 based on the addition of free cutting elements.
  • Cause Analysis of Unqualified Inspectionof H13 Hot Work Die Steel after Annealing
    HU Lianxin, ZHOU Jian, LIN Peng, CHI Hongxiao, MA Dangshen
    Materials For Mechanical Engineering. 2017, 41(Z2): 18-22.
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    Microcrack defects in the center of H13 Hot working die steel were detected by ultrasonic inspection and macrostructure test. In this paper, the cause of microcrack die steel was analysed by optical microscopy,scanning electronic microscopy and energy dispersive spectrometer.The results indicated that the severe microstructure segregation formed in ingot solidification process and internal stress caused by the large amount of brittle Al2O3,Al2O3-MnS compound inclusionsand blocky eutectic carbidesin thesegregation bandswere the causes of micro-cracks in the center area.
  • Microstructure and Properties of FS2738 Pre-hardened Plastic Mould Steel Large Block
    RU Yabin, LIU Baoshi, LIU Wei, CAO Lihong, YU Zongyang, TAN Kai, TANG Liang, YU Haipeng
    Materials For Mechanical Engineering. 2017, 41(Z2): 23-25.
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    In different parts of the chemical composition,inclusion and microstructure analysis of size for 810 mm x 1320 mm FS2738 pre-hardened plastic mould steel modules anatomical analysis,determined the overall strength of the module distribution. The results show that the hardness of the entire module difference is less than or equal to 2.5 HRC, module pre hardening after tempering martensite and tempered bainite composition,chemical composition of a uniform,less inclusions,can meet the requirements of large sized plastic products industry.
  • Effect of Cooling Type on Microstructure and Poperties of 10Ni3MnCuAl Rolling Flat Steel
    FENG Shuling, LIU Ming, CAI Qing, YUE Caichao
    Materials For Mechanical Engineering. 2017, 41(Z2): 26-29.
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    The effect of different cooling type after rolling on microstructure, grain size and the impact properties of 10Ni3MnCuAl rolling flat steel were studied by OM,SEM and impact experimenter. The result show that,the microstructure of water cooling type after rolling was mainly lath martensite, the microstructure of air cooling type after rolling was mainly granular bainite. The uniform and fine martensite structure after water cooling was acquired, granular bainite after air cooling was relatively thick. The impact value of water cooling type was reached 19.6-30.5 J, 2-3 times higher than the value of air cooling type,hardness increase about 2.5 HRC at the same time. The microstructure, grain size and the impact properties of 10Ni3MnCuAl rolling flat steel after water cooling were better than air cooling type.
  • Effect of Solution Cooling Method on Microstructure and Properties of 10Ni3MnCuAl Mould Steel
    HU Yidi, CHI Hongxiao, ZHOU Xiaolong, ZHOU Jian, MA Dangshen
    Materials For Mechanical Engineering. 2017, 41(Z2): 30-33.
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    Effect of solution cooling method on microstructure and properties of 10Ni3MnCuAl plastic mould steel were studied. Results show that 10Ni3MnCuAl steel can obtain the better comprehensive mechanical properties, after heat treatment by solid solution treatment at 880℃ for 12 h, oil cooling, and aging treatment at 530℃ for 40 h. The impact energy is 25.6 J. The microstructure of different heat treatment process was analyzed, the oil cooled microstructure is mainly contain lath martensite, lath bainite and a small amount of residual austenite. The slower cooling rate of furnace cooling will promote the phase boundary carbides precipitate, promote the decomposition of the M/A islands, and then significant deteriorated the impact toughness.
  • Melting Process of High-Performance Hot Work Die Steel 1.2344EFS
    MU Feng
    Materials For Mechanical Engineering. 2017, 41(Z2): 34-35,39.
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    This paper studied the effect of different melting process on purity and impact toughness of steel 1.2344EFS, and made a brief introduction of the technical advantage of UHP deoxydation process. Results show that for steel 1.2344EFS, with UHP+LF+VD melting process,[O] content can be controlled below 15 mg/kg,[P] content was reduced from 0.020% to lower than 0.010%,[S] content was reduced from 0.015% to lower than 0.003%, hence increased steel purity and impact toughness.
  • Development and Performance of High-quality 1.2367 Steel
    MA Zhijun, XU Huixia, XU Wenying, ZHANG Jialin, ZHANG Jianjian
    Materials For Mechanical Engineering. 2017, 41(Z2): 36-39.
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    Two types of 1.2367 steel 220 mm×810 mm and Ø220mm were developed. The hardness of the test steels under different quenching and tempering processes and the impact toughness and tensile properties in the range of 46-48 HRC hardness were studied. The results show that tempering secondary hardening peak temperature was 510℃ and the peak hardness was 56.6 HRC, the isotropic in the center of test steels reach to 90% after quenching at 1 050℃ and tempering at 620℃, the unnotched impact energy in the transversal direct and center of the 220 mm×810 mm size test steel reach to 371 J. 1.2367 steel has the application of higher temperature range and has higher strength and impact toughness compared with H13 steel.
  • Hole Defects Reasons Analysis and Improvement of H13 Steel Hot Forging Die Blank
    ZHANG Yandong, CHEN Lie, MIAO Hongsheng, HE Wencheng, HE Xiaolin, LI Juncheng
    Materials For Mechanical Engineering. 2017, 41(Z2): 40-43.
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    In the hot forging of H13 steel, hole defects often appear in the roughcast of the die, and samples are taken at the defects, and the causes of the hole defects are examined and analyzed. The results show that the internal mold blank hole defects is due to the presence of carbide eliquation, inclusions and other defects in steel metallurgy, steel in upsetting, from defects form stress concentration appears in the impact load stress cracks, with the increase of continue to impact load and deformation, the crack expanded form holes; main causes of carbide eliquation, osteoporosis is caused by the high temperature casting steel, through the optimization of casting process of steel, so that the mold blank forging hole defects basically elimination.
  • Development of Pre-Hardening Die Steel LN17 for Glass
    RU Yabin, LIU Baoshi, KANG Aijun, LIU Wei, CAO Lihong, MU Lifeng, YU Dan, SHEN Lin
    Materials For Mechanical Engineering. 2017, 41(Z2): 44-46.
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    The chemical composition of glass die steel LN17 was designed. The process of EAF+LF+VOD+ESR smelting, forging and pre-hardening was used to produce the steel. The microstructure and properties of the steel were analyzed. The results showed that LN17 steel pre-hardening, hardness deviation less than 2 HRC and the organization for the uniform sorbite microstructure and residual austenite of 14Cr17Ni2 steel, a comprehensive mechanical performance has greatly improved.
  • Productive Technology and Mechanical Property of 5CrNiMoV Steel Forging Die Block
    YAN Yun, LIU Baoshi, MA Ye, MU Feng
    Materials For Mechanical Engineering. 2017, 41(Z2): 47-49.
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    This paper studies the productive technology and mechanical property and microstructure of 5CrNiMoV steel forging die block. The results show that we can produce high quality 5CrNiMoV steel die block though forging technology and treatment technology. We had tested the mechanical property and microstructure on central position and 1/4 diagonal position with vertical and lateral of the die block. Tests show that 5CrNiMoV steel die block has nice function and it could meet requirements of users.
  • Factors Effect on Rough Rolled 120 mm Square Billet Quality of A8MOD Steel
    CAO Lihong
    Materials For Mechanical Engineering. 2017, 41(Z2): 50-51.
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    This paper studied the effect of different rolling process on quality of 120 mm square billet of A8MOD steel. Research shows that the quality can be significantly improved by controlling the amount of reduction and the rolling speed, thus solving the problem of central porosity and internal cracks of 120 mm square billets.
  • Influences of Homogenizing Annealing Time on Microstructure and Eutectic Carbide of Small Forging Piece of H13 Steel
    LIN Peng, MA Dangshen, CHI Hongxiao, ZHOU Jian
    Materials For Mechanical Engineering. 2017, 41(Z2): 52-56.
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    In view of the problem of eutectic carbide in hot work die steel forging H13 steel of small size,by using acid washing、OM and heat treatment experiment,influences of homogenizing annealing time on microstructure and eutectic carbide of small forging piece of H13 steel were studied. The results were that after 5 hours of homogenizing annealing for H13 steel,there were no widmanstatten structure and burned grain boundary.5 hours can be the best annealing time for homogenizing annealing of forging H13 steelof small size.
  • Annealing Microstructure Homogenization of Cr13 Corrosion Resistant Plastic Die Steel
    LIU Ming, FENG Shuling, MA Ye
    Materials For Mechanical Engineering. 2017, 41(Z2): 57-61.
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    In this paper, annealing microstructure of three types of Cr13 corrosion resistant plastic die steel were researched, contrast and analysis of six different heat treatment process, in order to get homogeneous pearlite spheroidization microstructure. The results show that, the best spheroidizing annealing process of 420MOD steel was isothermal annealing of 830℃+760℃, the best spheroidizing annealing process of 1.2083 steel was quenching of 960℃ add isothermal annealing of 830℃+760℃, the best spheroidizing annealing process of FT64 steel was quenching of 960℃ add annealing of 870℃. 420MOD and 1.2083steel should avoid preservation period of about 870℃,to form lamellar pearlite and chain microstructure at this stage. The quenching process before FT64 steel annealing could eliminate banding distribution of secondary carbides.
  • Effect of Heat Treatment on Microstructure and Properties of High-Mn Austenitic Hot Work Die Steel
    LI Jing, ZHANG Yi, SHI Chengbin, QI Yongfeng, ZHU Qintian, YU Wentao
    Materials For Mechanical Engineering. 2017, 41(Z2): 62-66.
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    In order to develop hot work die steel which can be used for service at 700-900℃, the microstructure and properties of new austenitic hot work die steel are studied in this paper. The results show that the microstructure of the high-Mn as-cast electroslag remelting (ESR) ingot is composed of γ-Fe, V(C,N), Mo2C. V(C,N) is irregular multilateral strip or slice shape with severe angles. Most of eutectic carbides Mo2C are lamellar fish-skeleton-like, except rod-shaped. With increasing solid solution time and temperature, the Rockwell hardness increases first and then decreases, and the austenite grains increase slowly. When the solution temperature exceeds 1 170℃, the austenite grain size increases linearly. The optimal combination of hardness and austenitic grain size can be obtained by soaking for 2 hours at 1 170℃. The maximum Rockwell hardness is 47.24 HRC, and the corresponding austenite average grain size is 58.4 μm. Compared with the single-stage aging, the maximum impact energy of the specimen after two-stage aging heat treatment reached at 16.2 J and increased by 29.6%, while the hardness decreased by 1 to 2 HRC. The optimum aging heat treatment process is subjected to pre-aging treatment for 1 hour at 650 ℃, and finally by re-aging for 1 hour at 780 ℃.
  • Effect of Quenching and Tempering Temprature on Microstructure and Hardness of Hot Working Die Steel 4Cr5MoSiV
    LIU Ming, YUE Caichao, FENG Shuling, MU Feng
    Materials For Mechanical Engineering. 2017, 41(Z2): 67-70,73.
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    Microstructure and hardness of 4Cr5MoSiV steel quenching and tempering have been observed and analysed by metallographic microscope and the hardness tester. The result show that, carbides of 1 040℃, 1 060℃ quenching were not completely dissolved in austenite, martensite microstructure becomed thicker increases with the quenching temperature; Hardness increased first and then decreased with temperature raised, maximumvalue was 56.5 HRC at 1 100℃; Grain size decreased gradually with the increased of temperature. The solubility of carbides in autenite had a great effect on the hardness of martensite transformation. Tempering was at the range of 490℃-560℃ after 1050℃ and 1 100℃ quenching, obtained different microstructure, and many types of carbides were precipitated in the tempering microstructure, mainly including M23C6 and M6C, tempering hardness wasobviously improved by those carbides of microstructure.
  • Smelting Process Method of Reduction Oxygen Content in the Steel H13
    ZHANG Yandong, CHEN Lie, HE Wencheng, JIANG Taiqiong, XIAO Leilei
    Materials For Mechanical Engineering. 2017, 41(Z2): 71-73.
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    The H13 EAF+LF+VD steel smelting, optimized by LF deoxidation of steel, aluminum and carbon powder with diffusion deoxidation, control the basicity of slag in the 2.5 to 3.5 range, and the use of vacuum degassing, weak and argon argon stirring process. Experimental results show that the optimization of H13 steel after deoxidation, the oxygen content in steel decreased significantly. The average oxygen content is reduced from 25.37 mg/kg to 13.53 mg/kg; T[O] ≤ 20 mg/kg ratio increased from 26.92% to 98.37%; the inclusion type A +B type +C type +D type average class level from the original 2.74 reduced to 2.35.
  • Productive Technology and Mechanical Property of SM55 Steel Cavity Forging Die Block
    MA Ye, YAN Yun, YU Haipeng
    Materials For Mechanical Engineering. 2017, 41(Z2): 74-76.
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    This paper studies the forging productive technology,microstructure and property of SM55 cavity forging die block. The results show that we can produce SM55 cavity die block though the productive technology include that repeatedly forging times and directions,controlling the rolling reduction of different forging times and directions, using specialtools forging the cavity. The outline of cavity forging die block is excellent. We have tested the vertical mechanical property and microscopic structure of SM55 cavity die block. Tests have shown that SM55 steel cavity forging die blockcan satisfy requirements ofthe using measures.
  • Heat Treatment of DT345 Pre-hardened Plastic Die Steel
    YU Hong, GUO Libo
    Materials For Mechanical Engineering. 2017, 41(Z2): 77-80.
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    The microstructure and property of the newly-developed DT345 pre-hardening plastic die steel after different heat treatment processes was studied. The result shows that if on-line pre-hardening inlet temperature is at 850℃ to 880℃, and make outlet temperature is less or equal 200℃ and tempersthrough 500℃ to 530℃, which can make the pre-hardening hardness reaches at 40 HRC to 43 HRC,strengh value achieve 1 140 MPa to1 270 MPa and impact value reach 260 J to 270 J. The new product can meet the user's requirement with high-hardness and all-round performance objective.
  • Effect of Heat Treatment Process on Microstructure and Mechanical Properties of 1.2367 Steel
    SUN Xiuhua, LIU Baoshiand, WEI Wentao
    Materials For Mechanical Engineering. 2017, 41(Z2): 81-84,88.
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    By testing of different heating temperature and cooling quenching and tempering at different temperatures of heat treatment of 1.2367 steel, through hardness test, microstructure observation, impact test comparative analysis method, the optimum heat treatment process was determined and the corresponding microstructure, performance were analysised. The results show that the optimum heat treatment process is 1 010 to 1 040℃ heating oil quenching, tempering 550 to 600℃; the hardness of 45-50 HRC, transverse impact energy more than 300 J, can meet the hot die hardness and impact toughness of high temperature performance requirements.
  • Influence of Heat Treatment on Microstructure and Hardness of Cr12W Steel
    CAO Ying, SUN Xiuhua, LU Wei
    Materials For Mechanical Engineering. 2017, 41(Z2): 85-88.
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    The microstructure and hardness of Cr12W steel with optical microscopy and hardness tester were analyzed. The influence on microstructure and hardness of different annealing process, quenching and tempering process were studied.The results indicate that after annealing at 860℃, uniform and spherordizing microstructure can be obtained and hardness is 240 HBW. With the increase of quenching temperature, the amount of carbides is decreasing. Cr12W has fine microstructures after quenching at 960-980℃ and reaches maximum hardness at 970℃.Punching die is used with high hardness, so low temperature tempering is chose,and the hardness reaches 60 HRC after tempering at 200℃.The tempering stability and impact toughness of Cr12W steel is better than Cr12 steel,and the microstructure is finer.
  • Microstructure and Mechanical Property of 4Cr3Mo2VNiNbB Hot Working Die Steel
    YAN Yun, LIU Baoshi, MA Ye, MU Feng
    Materials For Mechanical Engineering. 2017, 41(Z2): 89-91,95.
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    The mechanical properties and microstructure of hot work die steel 4Cr3Mo2VNiNbB were studied. The results show that the EAF+LF+VD+ESR process can produce high-purity steel 4Cr3Mo2VNiNbB; after quenching and tempering heat treatment,with transverse impact and excellent tensile properties, and homogeneous microstructure; mechanical properties and microstructure of the oil cooling condition are not very different from those of air cooling.
  • Influence of the Remelting Slag on Metallurgical Quality of a Kind of Fe-base Superalloys Electroslag Ingot
    WANG Yangyang, KANG Aijun, WANG Zhigang, HAN Kui, ZHANG Peng, WANG Aizhu, BIAN Songtao
    Materials For Mechanical Engineering. 2017, 41(Z2): 92-95.
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    75%CaF2-15%Al2O3-10%CaO ternary slag series and quarternary slag series of 60%CaF2-20%Al2O3-10%CaO-10% were used for electroslag remelting to prepare iron based superalloys slag ingot, and the comparison and analysis were made. The results show that the smelting quarternary slag series, Al, Ti elements in the alloy is damaged seriously, the particle size of inclusions is too small, the distribution is scattered, electroslag ingot surface quality has been significantly improved; melting point and conductivity of ternary slag series low and high viscosity, but two kinds of slag the density difference is not significant.
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