Papers by Keyword: Creep Property

Abstract: Rapidly solidification/powder metallurgy (RS/PM) Mg-6Zn, Mg-6Zn-5Ce and Mg-6Zn-5Ce-1.5Ca (wt.%) alloys were produced via hot extrusion with RS powders, produced by atomization-twin roll quenching. Microstructures, mechanical and creep properties of the alloys were investigated. The results showed that for the Mg-6Zn alloys with 5wt.%Ce and 1.5wt.%Ca additions, the microstructures of the alloys were gradually refined, which caused the strength of the alloy at room temperature to increase remarkably, especially for the RS/PM Mg-6Zn-5Ce-1.5Ca alloy, exhibited a high compressive strength of 394MPa at room temperature. At elevated temperatures, due to the fine and stable intermetallic compounds i.e. Mg_xZn_yCe_z and MgxZnyCez-(Ca) phases were formed for the Mg-6Zn-5Ce alloy and Mg-6Zn-5Ce-1.5Ca alloys, respectively, and the thermal stability of the ternary phase was a little lower than that of the quaternary phase because of the dissolving of Ca into the Mg_xZn_yCe_z phase, the mechanical and creep properties at elevated temperatures increased remarkably with Ce and Ca additions, especially for the RS/PM Mg-6Zn-5Ce-1.5Ca alloy, which exhibited a high compressive strength of 258MPa at 200°C, and the minimum creep rate was decreased about 2 times, compared with that of the Mg-6Zn-5Ce alloy.

Abstract: Present work describes an approach to identify creep properties of P91 with finite element simulations and neural networks. The small punch test was used to determine the material property under high temperature. Results showed that, the neural networks could be used to evaluate the creep property together with the small punch creep test and finite element simulations.

Abstract: Resin concrete is a new material which can be made into machine bed instead of the traditional pieces of gray cast iron as the machine base, it can improve the dynamic stiffness of machine tools and the quality of machined parts, and extend the campaign life, reduce noise and improve efficiency. However, due to the long-term effect of load of the resin concrete, the elastic deformation occurs in its component, and the strain will increase over time. Thus it can affect the resin concretes service life, and the calculation of creep has become an urgent task in structure design and use, which should be taken seriously. In this paper, the bending creep properties of resin concrete beam were studied and analyzed by using four-point bending test method. The creep curve under different load levels were obtained, and the viscoelastic properties were analyzed.

Abstract: Creep property of coarse-grained soil is an important property influencing long-term settlement of embankment. Based on the H-K creep model which is consistent with the experimental results and verified by uniaxial compression creep test, relationship between fine grain composition and creep parameter and pattern of creep property of sandy slate coarse-grained soil influenced by fine grain composition are studied. It turns out that fine particle content is the important factor that affects creep property of sandy slate coarse-grained soil and using fine particle content of 30% is able to decrease long-term settlement of embankment.

Abstract: The room-temperature mechanical properties of the extruded Mg-5Li-3Al-2Zn-2Cu alloy (LAZ532-2Cu) were researched previously. In this paper, the creep behavior of the extruded LAZ532-2Cu alloy was studied at the temperature range from 398K to 448K, with the stress 60MPa, 80MPa and 100MPa. The microstructure of the alloy consists of the matrix α-Mg solid solution and the intermetallic compounds on the grain boundary or in the grain. The microstructural analysis of the alloy reveals the correlation between microstructure and creep properties. The stress exponent n 3.72, 4.8, 6.1, the activation energy Qc 94.8kJ/mol, 123.9kJ/mol, 128 kJ/mol were calculated at the test condition. The creep test samples were combined with detailed transmission electron microscopy and X-ray diffractometry in order to characterize the precipitated AlLi phase, which contributes to the creep resistance by obstructing the dislocation movement in dislocation creep.

Abstract: The microstructures of a series of high Zn magnesium alloys Mg-(7-11) Zn-(2-6) Al alloys were clarified, and effects of Zn and Al concentration about the ZA system alloys on the microstructure and properties were also investigated. For Mg-(7-11)Zn-4Al alloys with the Zn content increase, improved creep resistance is obtained due to block τ-Mg₃₂(Al, Zn)₄₉ phase, with severe reduction in ultimate strength and ductility, and the best creep property is obtained with 11wt.% Zn concentration. However, a bit increasing Al content of Mg-9Zn-(2-6)Al alloys contributes to the improvement in the ambient and elevated-temperature yield strength, but seriously deteriorates the creep properties for the formation of lamellar φ-Al₂Mg₅Zn₂ eutectics or Mg₅₁Zn₂₀ phase.

Abstract: Coarse-grained soil is widely used in subgrade engineering, creep property of which is the important factor that affects long-term settlement of fill embankment. The creep property of sandy slate coarse-grained soil under different moisture conditions is analyzed through uniaxial compression creep test on influence rule of moisture content on creep of coarse-grained soil. Relations between moisture contents and creep parameters are studied on the basis of H-K Creep Model. It turns out that moisture content is the important factor that affects creep property of sandy slate coarse-grained soil and using dry or saturated coarse-grained soil is able to decrease long-term settlement of embankment.

Abstract: Using alumina-rich MgAl₂O₄ spinel AR78 and 97 fused magnesite as raw materials, brine as the binder, magnesia alumina spinel bricks close to theoretical composition and spinel bricks with zirconia have been prepared. Then the influences of zirconia on the properties of MgAl₂O₄ spinel bricks are researched. The results show that: (1) After the addition of zirconia, the direct bonding structure formed between spinel and zirconia can strengthen matrix structure and promote sintering, so the structural properties, the alkali resistance performance and the creep property of MgAl₂O₄ spinel bricks are all improved. (2) The optimal addition of zirconia is 6%, with which the spinel bricks have well alkali resistance performance and creep property of which the final creep rate is -1.46% after creep experiment for 50h.

Abstract: Using alumina-rich MgAl₂O₄ spinel AR78 and 97 fused magnesite as raw materials, brine as the binder, magnesia alumina spinel bricks close to theoretical composition have been prepared. Then the high temperature creep experiments are carried on. The creep property is analyzed by microstructure and creep curve. The results show that: (1) The magnesia alumina spinel bricks close to theoretical composition prepared have well sintering performance and compact structure.(2) The specimen 1# has the best creep property, of which the final creep rate was -1.45% after creep experiment for 50h. (3) Under high temperature and pressure for a long time in creep experiment, the internal of spinel is further sintered, the pores of the specimens are rearranged.