Advanced Materials Research Vols. 1120-1121

Abstract: This article studies optimization design of Vibratory stress relief (VSR) technology parameter for large welded components. The test is carried through a large welded truss. It first analysis key factor of the influence on VSR technology effect. And then by modal analysis, we’ve got the natural frequency and natural modes of the specimen , The optimization design is based on residual stress distribution and natural modes of component for VSR process parameters. Test pieces are treated by vibration. before and after vibration, residual stress of the specimens is measured by the method of blind hole.The results showed that vibration mode is a key factor in determining the effect of VSR. Stress distribution is more complex for large welded components.As accordance by selecting a few of vibration modes, for VSR main technical parameters design, it can get enough vibration displacement in the areas and directions of component with residual stress. Thus we can have a good effects to relief welding residual stress.Three major parameters (Excitation frequency, excitation point, support points) are related with vibration mode. They are decided by selecting vibration mode. Excitation force is decided based excitation frequency as well as the size of the exciter eccentric , to get the right excitation force by adjusting the size of the exciter eccentric under the condition of the selected excitation frequency.

Abstract: This paper applied the micro-arc oxidation technology to TIG weld joint based on titanium alloy. The optical microscope, SEM, XRD and polarization curve were used to analyze the joints metallographic phase, the coating morphology, the phase composition and corrosion resistance. Research results showed that the grain was grew gradually coarser from base metal to joint. The joint surface obtained a uniform morphology after micro-arc oxidation. The joint and base metal was made up of α-Ti and their coatings are mainly composed by rutile-TiO₂. The surface morphology and phase composition are similar after micro-arc oxidation. Polarization curve tests demonstrated that the corrosion potential performance of the coating was enhanced by micro-arc oxidation.

Abstract: Calculation technique in order to reconstruct the 3D temperature field and predict the microstructure and mechanical properties of the weld metal in hybrid laser-arc welding is developed. The technique is based on the solution of the direct 3D temperature problem by a function-analytical method, the numerical solution of the inverse problem for the unknown parameters of a volume heat source, the employment of the known models for prediction of the microstructure and mechanical properties. The proposed calculation technique makes it possible to reduce considerably the total time for data input and solution. It is demonstrated with an example of butt hybrid laser-arc welding.

Abstract: Over the years, with the increasing development of engineering materials, the emergence of new composites, fiber metal laminated, biomaterials, metal alloys etc., and with demand for products less expensive, less polluting and more efficient, the manufacturing engineering also needs to develop to be able to process these new materials. Materials and tool geometries, intelligent mechanisms, modular machines, also follow this setting. To that end, this work comes to raise the main parameters that influence in the hole quality surface of finished product. Were used two polymeric materials, ultra high molecular weight polyethylene (UHMW-PE) and polytetrafluoroethylene (PTFE), two feed rates, three rotations and three tool geometries, allowing to identify which of these parameters have greater influence on the thrust force and the characteristics of the finished product and dimensional deviation.

Abstract: Considering the rotary hearth furnaces (RHF) direct reduction process, using bamboo char, charcoal and straw fiber as reducing agents added into the carbon containing pellets, the experimental study on the impact of reduction effect has been conducted from metallization rate, compressive strength and volumetric shrinkage. Test results showed that biomass reducing agents can replace traditional reducing agents used in the RHF direct reduction process. Compared with traditional reducing agents, biomass has less of effect on metallization rate, but different biomass reducing agents have large impact on strength and volumetric shrinkage of pellets. The compressive strength of pellet with straw fiber is relatively higher, and the compressive strength of pellets with charcoal or bamboo charcoal is low, for reaching the production requirement, which will be improved at higher temperature (1300°C). Using bamboo charcoal as reducing agent will lead to the swell of pellets in the beginning stage, and this situation will make the volumetric shrinkage at high temperature lower, finally, all of these will affect the strength of pellets and the heat-transfer between different material layers, thus it should be used accompanying with other reducing agent.

Abstract: Electron beam welding technology is a mature special welding technology. The advantage of electron beam welding like these: high power density, high ratio of depth-to-width, high-quality welds. Electron beam welding equipment has been independently developed by tracking and bringing in. Electron beam welding technology has a wide range of applications in the aerospace, automotive, medical and other branches of industry, the field of applications is also expanding with the improved welding equipment. According to the demand of research and market, Electron beam welding technology will move toward the direction of universal, integrated, information-oriented in the future.

Abstract: This paper briefly introduces the fabrication of SMT template and laser cutting technique,analyzes the factors that influence the SMT template fabrication and the laser cutting quality. Then it studies the improvement measures and methods through practical applications.

Abstract: Wheat milling process involves multiple grinding procedures, the wheat powder particles size in different grinding procedure are difference. In order to study the influence of particle size of wheat powder on roller wear performance in different grinding procedure, abrasion experiments were carried out by MLS-225 three-body abrasive wear tester, while different sizes were chosen as abrasive, alloy white iron which frequently used as roller metal materials was chosen as wear sample, wear weight loss and surface microstructure were chosen as the main evaluation indicators. The results showed that the weight loss of samples were showed a linear relationship with wheat the size of wheat powder. The main wear behavior was mainly mechanical polishing while particle sizes was smaller one. For the larger size, wear was made by multiple plastic deformation and low cycle fatigue wear mechanism.

Abstract: Carbon black suspension is investigated using a squeezing test, which compresses a disk of paste between two parallel plates, one of which is moving at a constant speed. From this test, the two-phase nature of carbon black suspension can be evidenced. Liquid migration is observed at low compression speed. This test is also a good tool for constructing a two-phase model for paste flow modeling. The concentrated suspension is composed of a powder of activated carbon black and a Newtonian liquid phase.

Abstract: In this research, a heat pipe with grooves was experimentally analyzed for the application in thermal management of electronic packaging. The heat pipe was produced by a copper tube with an outer diameter of 9.45 mm, length of 205 mm, and capillary structure composed by axial grooves with average diameter of 220 μm. The grooves were manufactured using wire electrical discharge machining (wire-EDM). The working fluid used was de-ionized water. The condenser was cooled by air forced convection and the evaporator was heated using an electrical resistor. This heat pipe was tested horizontally to increasing heat loads varying from 5 to 15 W. The experimental results showed that the heat pipe worked successfully.