LIU Ning CUI Kun Huazhong University of Science and Technology
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Wuhan.China DENG Zonggang Hefei University of Technology
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Hefei
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China CHENG Benpei KONG Jie Institute of Solid State Physics
,
Academia Sinica
,
Hefei
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China Doctorate student
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Department of Mechanical Engineering No.2
,
Huazhong University of Science and Technology
,
Wuhan 430074
,
China
金属学报(英文版)
Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2(M2)melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites grow into the melt and then the fine equiaxed cellularstructure appears in upper melt region nearly surface.The substructure of cellular grains anddendrites was observed to consist of martensite and retained austenile,while the carbides asM_6C_■ Cr_7C_3 and MC distributed at their boundaries.It is believed that the highermicrohardness up to HV_(0.1)=865-960 of the laser fused structure of the alloy is due to the oc-currence of martensite.
关键词:
High speed steel W6Mo5Cr4V2(M2)
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LIU Zaihua Huazhong University of Science and Technology
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Wuhan
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China ZHAO Dongli Bureau of Complete Sets of Equipment
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State Machinery Commission
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Beijing
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China Dept.of Mechanics
,
Huazhong University of Science and Technology
,
Yujiashan
,
Wuhan
,
China
金属学报(英文版)
The size effect of tension round bars with circumferential crack was described and used to measure the plane-strain fracture toughness K_(1c) of median or low strength steel.The size of cylindrical specimen required for K_(1c) measurement is much smaller than that of standard specimen.The J-integral values of the cylindrical sqecimens were calculated to characterize the size effect.The finite element calculution and fracture morphology analysis have been conducted to eyplain the fact that smaller cylindrical specimen could be used to measure K_(1c) of median or low strength steel.
关键词:
median or low strength steel
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ZO U Hongcheng DAI Shujuan QIAN Zhixiong LI Guangxia Huazhong University of Science and Technology
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Wuhan
,
China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A207—A212
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Associate Professor
,
Division of Materials
,
Huazhong University of Science and Technology
,
Wuhan
,
China
金属学报(英文版)
The change of microstructure of fatigue specimens before and after laser radiation was studied by transmission electron microscopy.The results show that the diameter of dislocation cell λ tends to a constant at fatigue failure.Based on the principles of continuous damage mechanics,expressions of the fatigue damage criterion and processes of fatigue damage evolu- tion for L Y12CZ have been derived.
关键词:
laser radiation
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TAO Zengyi LUO Jiaming Huazhong University of Science and Technology
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Wuhan
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China TAO Zengyi
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Faculty of Metallic Materials
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Dept.of Mechanical Engineering No.2
,
Huazhong University of Science and Technology
,
Wuhan 430074
,
China
金属学报(英文版)
The influence of laser surface melting and induction hardening on the surface structure,con- tact fatigue life and failure behaviour of the nodular cast iron has been investigated.The con- tact fatigue life can be improved by both laser treatment and induction hardening,but the fail- ure process and type are different from each other.The former is due to lumpy and deep spal- ling caused by crack propagation between the quenching zone and the substrate,and the latter is due to nubby and surface flaking caused by the oil wedged action into surface cracks.
关键词:
surface hardening
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XIE Changsheng SUN Peizhen ZHAO Jiansheng CHEN Yuqiu Huazhong University of Science and Technology
,
Wuhan
,
China XIE Changsheng Associate Professor
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Department of Mechanical Engineering No.2
,
Huazhong University of Science and Technology
,
Wuhan 430074
,
China
金属学报(英文版)
The microstructures of Fe-Mn-Ni-Cr steels with medium carbon and the effect of alloy ele- ments on them have been investigated by means of X-ray diffraction quantitative phase ana- lyses,metallography and hardness tests.The volume fraction of martensite in steels quenched at 1100℃ can be expressed as: f_M~(1100)=162.643-15.482Mn-7.36Ni-4.286(Cr+Mo+V) Based on this expression,the quasi-equilibrium microstructure diagram has been obtained.It is shown that the effect of Mn on the austenite stability is greater than that of Ni.The equiva- lent [Ni]=2.104Mn+Ni and equivalent [Cr]=Cr+Mo+V. The driving force for martensite transformation at M_s point has been calculated to he drastically decreased by element Mn.
关键词:
quasi-equilibrium microstructure diagram
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REN Zhifeng ZHA NG Chengfu Huazhong University of Science and Technology
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Wuhan.China Professor.Division of Casting
,
Huazhong University of Science and Technology
,
Wuhan
,
China
金属学报(英文版)
It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional supercooling proposed in previous literatures but also the supercooling due to the effect of curved surfaces at the solidifying from.The greater entropy of fusion and the tendency to faceted face are important features of the non-metallic phase,which may con- tribute to the leading,role of the phase during solidification.It might be the change of leading phase that changes the morphology of crystals.
关键词:
composite-in-situ
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