Advanced Materials Research Vol. 487

Abstract: ANSYS was employed to build nonlinear finite element models of seal structure of double-Y and quad-ring between the piston and casing of rapping device respectively. The relationships of the contact stress versus fluid pressure and the Von-Mises equivalent stress versus working pressure of fluid were obtained. The comparison of the two calculated results presented the seal structure of double-Y was proper for rapping device between the piston and casing.

Abstract: Using the PRO-E to build the 3D model of plastic closures and analyze the main shortages of the plastic closures and the corresponding countermeasures; the influencing factors like the polymer injection location, the pressure, the temperature and the time in the plastic closures molding process are studied in this paper based on Moldflow. The injection closures molding parameters, such as the pressure maintaining, the cooling, and the bucking deformation are optimized with numerical simulation.

Abstract: In the present study, the friction and wear behaviors of copper-graphite composite against GCr15 steel in high-speed sliding with current were investigated. The worn surfaces and wear debris were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), and the wear mechanisms were discussed. It shows that the current plays an important role in the high-speed dry sliding of copper-graphite composite against GCr15 steel. With increasing current, the friction coefficient decreases, and the wear rate increases. The wear mechanisms of the copper-graphite composite are main abrasion and fatigue without current, and that of with current are main fatigue, arc ablation.

Abstract: The compressive Properties and the effect of anti-damage were studied by means of compression and pre-compression damage tests. The study indicated that：The fracture mechanisms of compression tests were quasi-cleavage fracture attributed to the normal stress and shear stress. Fracture strength, the maximum strain and the fracture energy were reduced in varying degrees, and the damage was intensified while increasing preload value. The mechanical property of the TiAl alloy degrades because of the present of the cracks, and large amount of micro-cracks appear on the surface firstly.

Abstract: It is impossible to keep pipelines free from defects in the manufacturing, installation and servicing processes. In this paper, pre-tension deformation of X60 pipeline steel was employed to experimentally simulate the influence of dents and the fatigue fracture surfaces of X60 pipeline steel after per-tension deformation under cyclic loading were investigated. The results indicate that the static state tensile mechanics is the dominant factor in the fracture mechanisms at high stress ratio. With the decrease of the stress ratio R, the fractograph presents evident fatigue facture characteristics. The amount and intensity of MnS inclusion evidently increase with the loading frequency decrease and the typical cleavage fracture characteristics have been found.

Abstract: Discontinuous NiTi SMA thin films were deposited on PZT substrate by magnetron sputtering method with a specially designed pore plate. The microstructure and damping property of the prepared composite were studied with X-Ray diffraction, scanning electric microscopy and dynamic elastic modulus apparatus. It was found that NiTi SMA thin films with physical dimension of width of less-than or equal to 2mm and distance between the adjacent thin films of 1mm are of best equiaxed crystal microstructure after crystallization at 600°C. The damping effect of the composite is still caused by PZT and the damping value is generally lower than that of pure PZT, about 9.9%.

Abstract: Non-structural cracking of concrete is a serious problem and the underlying phenomena, namely, shrinkage and creep, need to be better understood. Much research has been devoted to this complex problem. However, despite major successes, the phenomenon of autogenous shrinkage is still far from being fully understood. The paper discusses the main aspects of concrete shrinkage, with a focus on autogenous shrinkage, which are especially important in low water/binder ratio concrete. These aspects include the theories of physical mechanism, prediction models and future research trends. Shrinkage of concrete due to moisture changes, which result in surface and capillary tension, was reviewed. The mechanisms often cannot be directly linked to the macroscopically observed dilatation/contraction. An overview of recent model developments is also presented.

Abstract: The growth behavior of the bainite obtained by short-time isothermal transformation at 200°C in the high carbon silicon-containing steel has been investigated. It is found that the bainite appears the plates consisting of single ferrite phase, and that both the lateral growth and longitudinal growth of bainite have weak ability to traverse the lattice-distortion strain fields and grain interface of austenite.

Abstract: The research use an impact test enginery, choose T10 steel samples, and do a low stress repeated impact collisions experiment. By comparing two kinds of different heat treatment of T10 steel, analyze and research its macro plastic deformation phenomena and plastic accumulation law in low stress repeated collision impact load, and observe its hardness change by hardness microscopicand and its metallographic structure by metallographic microscope to discuss its deformation causes.

Abstract: Heat transfer coefficient is one of the most important boundary conditions for quenching process simulation. It depends on many factors, such as material, size, surface conditions of a part, and so on. It is, therefore, difficult to evaluate the heat transfer coefficient accurately. T In the environment for large modules P20 and the actual heat transfer conditions, the off-line air-cooling heat transfer coefficient of C are simulated by using empirical equations.