A. G. Liu
,
X.F. Wang
,
L.P. Wang
,
S. Y. Wang
,
B. Y. Tang and P.K. Chu 1) Advanced Welding Production Technology National Key Laboratory
,
HIT
,
Harbin 150001
,
China 2) Department of Physics and Material Science
,
City University of Hong Kong
,
83 Tat Chee Avenue
,
Kowloon
,
Hong Kang
,
China
金属学报(英文版)
Plasma immersion ion implantation (PIII), unrestricted by sight-light process, is considered a proper method for inner surface strengthening. Two-dimensional simulation oj inner surface PIII process of cylindrical bores were carried out in this paper using cold plasma fluid model, and influence of the bore's dimension on impact energy, retained dose and uniformity of inner surface were investigated.
关键词:
plasma immersion ion implantation
,
null
,
null
,
null
Quanling PENG
,
S.M.McMurry
,
J.M.D.Coey
材料科学技术（英文）
Permanent magnet rings are presented, which exploit the image effect in the surrounding circular iron shields. The theory is given for a general permanent ring when the magnetization orientation φ at each coordinate angle ψ changes by φ=(n+1)ψ, where n is a positive or negative integer. For the uniformly magnetized case n=-1, the permanent ring produces no field in its bore, and the field is that of a dipole outside. When the ring is surrounded by a soft iron shield, its field becomes uniform in the bore, and zero outside the ring. The field can be varied continuously by moving the iron shield along the magnet axis. A small variable field device was constructed by using NdFeB permanent rings, which produced a field flux density of 0～0.5 T in the central region.
关键词:
External magnetic field
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null
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null
Materials & Design
Shrink fit is an important method used to connect mechanical parts but less studied by three-dimensional finite element method. Through a finite element method study, here we have simulated the crankshaft shrink fitting process by focusing on four main aspects: the optimization of heating method before shrink fit, the contact behavior on the interface in shrink fit process, and the structural distortion after shrink fit, as well as the evaluation of the bonding strength. Our results have demonstrated: (1) an extended bore with a satisfied radius can be obtained by imposing temperature gradient around the bore during the heating process. (2) In the beginning of the shrink fit, the journal tends to be absorbed into the shrink fit bore until the interfaces are fully contacted. The journal is then squeezed in radius and extended in axial as the heat transfer becomes stable through the interface. (3) The upper crankweb bends upward when heated, while downward after shrink fitted. The shrink fit distortion leads to the journal' offset and rotation in an individual shrink fit process, and the stacking offset of each journal aggregates the distortion in an integrated crankshaft as compared with the expected shape in an ideal state. (4) The interfacial bonding strength reaches a relative constant in a time that much shorter than expected. The final distribution of the contact pressure on the interface is not uniform but the maximum transmitted torque evaluated by finite element method agrees with that obtained via the proposed analytical method. In terms of these simulated results, a series of practical measurements have been performed with an aim of efficiently enhancing the bonding strength and preventing the shrink fit distortion. (C) 2010 Elsevier Ltd. All rights reserved.
关键词:
Ferrous metals and alloys;Mechanical fastening;Shrinkage;stress-analysis;fit;interference;design;fire
钢铁研究学报(英文版)
The stress-strain curves and microstructure properties of superalloy GH4169 was tested by thermal simulation experiment with different parameters, which were deformation temperature and strain rate and strain and original grain size. The influence of technology parameters on crystal grain size of dynamic recrystallization (DRC) was analyzed. The kinematics model of superalloy GH4169 was established, in which the relation between grain size of dynamic recrystallization and function Z (Zener-Hollomon) and parameters was described. The dynamics model of superalloy GH4169 was put forward, which described the relation between the quantity of dynamic recrystallization and function Z and parameters. The research results showed that the grain size of dynamic recrystallization increased with increasing the temperature and decreasing the strain rate. And the grain size of DRC bore no relationship to original grain size. And the quantity of dynamic recrystallization decreased with increasing the original grain size. Key words: GH4169 superalloy; kinematics model; dynamics model; thermal deformation
关键词:
GH4169 superalloy;kinematics model;dynamics model;thermal deformation
