Advanced Materials Research Vols. 139-141

Abstract: The flow stress of hot deformation about 0Cr13Mn stainless steel was experimentally studied by A Gleeble1500 thermo-mechanical simulator. The effects of deformed temperature, strain rate and strain to flow stress were analyzed. The prediction of RBF neural network with correlation between the flow stress and the chemical composition, deformed temperature, strain rate and strain, etc was established. Simulation data of the flow stress by RBF network with relationship between input and output for 0Cr13Mn stainless steel were stable. Accuracy of the prediction by RBF Neural network was higher than the regression precision by the multiple non-linear regression numerical models. Through a combination of the prediction by RBF neural network and numerical regression model of flow stress, the developing method of BPF neural network on-line calculation based on measured data of flow stress will be feasible under the condition of ensuring the accuracy of the premise.

Abstract: Grinding is one of the important machining processes for the WC-Co carbide product. Different grinding strategies will have different impact on the work piece material. This study focuses on the WC-Co carbide grinding process, and the effect of grinding condition on the WC-Co carbide microstructure, figures out the relationship between different grinding strategies and material microstructure which relate to the WC-Co carbide tool failure. A specific microstructure analysis with Scanning Electric Microscope (SEM) will be presented based on a series of grinding experiments. The residual stress that generated in the grinding process will also be discussed based on the X-Ray Diffraction (XRD) measurements. It has been found that micro cracks are generated at certain grinding conditions with certain level. The residual stress which generated in the grinding process can be calculated by the d-spacing shift, and the comparison results show micro-cracks level is corresponding with the peaks shift in XRD test.

Abstract: Two kinds of ceramic additives have been developed that one is the serpentine particles and another is a blend of serpentine particles and catalyst. The tribological properties of the addition of different additives are investigated through a series of friction and wear experiments. Wear surface and the composition of the tribofilm were examined by SEM, EDS and XPS. In case of single serpentine additive, tribo-film can be formed gradually on the worn metal surface. The friction coefficient is about 0.11. The tribofilm mainly consists of Mg and Si elements transferred from the additive. This can compensates part of wear mass loss, avoids the direct contact of the two rubbing surfaces, and thus effectively improves the anti-wear characteristics. In case of the blend oil additive, the tribo-film formed obviously on the worn surface in the initial stage and no obvious film at end of the test. However, the friction coefficient can lower even to 0.007~0.008 compared with the above experiment. The worn surface becomes very smooth. Chemical analysis shows that there is a very thin film of carbon concentration with thickness of 30~50nm on the worn surface. Existence of the very thin carbon-concentrated film and mirror-like surface generates super low friction coefficient.

Abstract: The Semi-Solid Processing technology is an innovation manufacturing process. The filling capacity of the semi-solid metal has very important effects on the properties and qualities of the work pieces. Lots of heat factors have effects on the filling capacity of semi-solid metal. The filling capacity of semi-solid AZ91D magnesium alloy has been studied by means of fluidity test. The results indicate that the filling length increases with the increasing of the temperature and the filling capacity of semi-solid magnesium alloy with shearing is better than that of without shearing. The lower temperature, the more obvious the effect of shearing on the filling capacity is. However, if the temperature is very low, the flow of the slurry is poor and the effect of shearing on filling capacity decreases. The microstructures of semi-solid magnesium alloy after shearing is spherical and homogeneous.

Abstract: Damage distribution and evolution of the HRR field are characterized by means of a two-scalar damage variable approach under the consideration of isotropic damage. This theory is based on the definition of thermodynamic conjugate forces and the postulation that the plastic damage surface corresponds to the initiation of plastic damage. An asymptotic solution is applied for the non-linear plastic damage evolution equations. It is shown that both the damage variables may be expressed as a function of the accumulated amount of overall damage respectively in exponential and tangential types, which determine the damage characteristics in different areas. It is also revealed that the damage evolution coefficient plays an important role to determine the distributions of the damage variables, effective Young’s modulus and Poisson’s ratio. The obtained largest damage variable, which characterizes the deterioration of the material, and the lowest effective Young’s modulus around the crack tip locate at and respectively for Mode I and II problems.

Abstract: As technology develops, digital image processing technology has become a new method for studying particle property and a necessary means for particle analysis. This method helps researchers to gain deeper understanding of microstructure and property of powder particles. In the paper, samples are composed with two kinds of cement powders: cement clinker and slag powder, which have different characteristics and shapes. The paper analyzed the characteristics of different ingredient and mixing evenness degree of cement sample by using the technology of SEM backscattered electron image and the theoretical calculation model. On the basis of experimental analysis, a new method was proposed to quantitatively analyze evenness degree for the cement mixture basing on image processing, which adopts the advanced microscopic analysis technology. This new method is tested by experiments, and results prove that this method is effective and is superior to other methods.

Abstract: Precipitation characteristics of second phase in low-carbon steel produced by FTSR technology have been researched by TEM and EDS in this article. And preliminary research of precipitation conditions of second phase particles in thermodynamics and dynamics have been took. The results indicate that: there’re second phase particles precipitated dispersively in hot rolled low-carbon steels by FTSR technology. These particles mainly contain particles of Al2O3, MnS and AlN, and the precipitate size is about tens to hundreds of nano. Thermodynamical analysis declares that most of the Al2O3 and all of the MnS, AlN particles are precipitated in solid state. That’s why the precipitation process is slowed down by the diffusion velocity of the elements in solid, and thinner particles are precipitated while the material is in solid state than in liquid state. Different from the traditional plate rolling production of Al-killed steel, the precipitation of AlN particles are mainly controlled by the continuous casting process in thin slab casting and rolling process, but almost no precipitation of AlN particles in the rolling process.

Abstract: At the ambient temperature, in the 0.2 M NaHSO3 and 0.6 M NaCl solution, by gravimetric test, potentiodynamic polarization curve test and electrochemical impedance spectra (EIS), the electrochemical behavior of 5083/6082 friction stir welding dissimilar weld and two parent materials were comparatively investigated. The results indicated: at the given processing parameters, the anti-corrosion ability of the dissimilar weld was superior to those of the 6082 and 5083 parent materials.

Abstract: Wood cell images are observed by the In-Situ SEM plays a very important role in wood structure. Because of the nature of cell image, automatic segmentation for wood cell image becomes one difficult question. According to the characteristics of image of anatomical structure of wood based on image processing theory, the theory and method of binarization algorithm for image of anatomical structure of wood is presented. The machine vision detecting of edge tracing of wood cell is processed to the binarized wood image. Use this method to dissected Yunnan ormosia and Manchurian ash image of anatomical structure of wood cell, this study provides the theory base for feature abstraction and pattern recognization for the further study on image of anatomical structure of wood

Abstract: Adhesive is an important part of ceramic-metal composite armor. In order to obtain excellent ballistic performance, some adhesive with a variety of content of nano-SiO2 was prepared, and mechanical properties and ballistic test were conducted. The results show that the pores in adhesive decrease the strength of the adhesive, and the fracture happens along with the pores. To add nano-SiO2 in adhesive can decrease the porosity and the scale of the pores. In the ballistic performance, the adhesive enhance the acoustic impedance, the greater acoustic impedance can increase the energy of transmission wave and decrease the energy of reflection wave, leading to that the ceramic is destroyed slightly. The targets with adhesive added in 20% nano-SiO2 express the best anti-bullet properties. There are so many big blocks left in targets and the height of back convex is only 2.36mm.