Abstract: Metallic hafnium has good comprehensive performance that makes it the preferred material for control rods of nuclear reactors. The elemental composition, mechanical properties, the corrosion resistance and the physical characteristics of hafnium plate are researched during the development of control rod for reactors. It proved the manufacturing method of hafnium plate is appropriate, characteristic of materials meet the requirement of a control rod.
Abstract: A parting surface, gate form and location were confirmed by analyzing the structure and technological characteristics of a crisper cover, respectively. The insertion and splice mold structure were adopted, and a multiple point gate three-plate injection mold was designed. The mould structure and operation process were introduced. This designd had reference value for the injection mold design of other product.
Abstract: Currently, speed detection of travelling block system is carried out mainly by detection roller speed, which results in a larger error. Against this background, a method to test crown block pulley was put forward, and its rotation speed precision and also its reliability were analyzed. The method is effective in improving detection accuracy and avoiding errors arising from skidding on the basis of applying the principle that rotation speed ratio of different fixed blocks is a constant value, thus judging the occurring of slipping by examining rotation speed for different fixed pulley. This method provides a guarantee for accurately controlling travelling blocks operational speed and height.
Abstract: In this work, a study of fatigue crack propagation (FCP) behavior of friction stir welding (FSW) joints of 7075-T6 aluminum alloy was carried out. Fatigue crack growth rate curves were determined for cracks growing in different locations of the welding lines, including prefabricated crack through welding seam center, advancing side (AS), retreating side (RS), and vertical to welding seam. A computational simulation of fatigue crack propagation was conducted by AFGROW with different stress ratios R, and the effects of R on FCP rate were analyzed. Results showed that the FCP rate in RS of the Heat Affected Zone (HAZ) was the lowest and the highest was in the region vertical to the welding seam. In the low stress intensity factor range (△K) region, the FCP rate in Nugget Zone (NZ) was lower than that in AS of the HAZ, but in the high △K region, the situation was contrary. Reasons of the results were analyzed. Compared with the standard of International Institute of Welding (IIW), FCP rates in all regions were lower and it concluded nice fatigue properties of FSW 7075-T6. The simulation made in terms of crack propagation rate (da/dN) versus △K generally showed a good agreement with the measured values. The study of effects of different R on FCP rates based on AFGROW indicated that FCP rates increased with increasing R.
Abstract: The feasibility of using Tandem Gas Metal Arc Welding (T-GMAW) to produce full penetration butt welds in 5mm ship panel steel plates has been assessed and compared to the current Submerged Arc Welding (SAW) process. Experiments conducted show that the T-GMAW process is feasible and demonstrated a significant improvement over the SAW process in several areas including higher travel speed, a reduction in filler material, significantly lower post weld distortion, and a smaller Heat Affected Zone (HAZ), while maintaining similar microstructure and mechanical properties in the weld metal and HAZ.
Abstract: Welding thermal cycle of SMA490BW corrosion resistance steel with different heat inputs were simulated by using Gleeble-3500 thermo-mechanical simulator to investigate the microstructure and impact toughness of the heat-affected zone (HAZ). The results shows that the microstructure of the coarse-grain heat affected zone(CGHAZ) is mainly composed of lath bainites and the surpass critical coarse-grain heat affected zone(SCCGHAZ) consists mainly of granular bainites with a small content of ferrites. The grain size increased with the heat input increasing, Besides, the impact energy of the surpass critical coarse-grain heat affected zone(SCCGHAZ) is higher than that of the coarse-grain heat affected zone(CGHAZ), when the heat input energy is 15kJ/cm after twice thermal cycle, the impact energy is highest.
Abstract: The grade-controlled filling behavior of vacuum counter-pressure casting thin wall aluminum alloy was studied by numerical simulation and experimental investigation. According to the analysis of filling behavior under fixed pressure and the casting structure, the technology of the grade-controlled filling of vacuum counter-pressure casting thin wall aluminum alloy was suggested. The result shows that the filling velocity was controlled on grade, resulting in the smoothly and sequential filling behavior, and the decreasing of defects in castings.
Abstract: By the method of adding MNP (micron or nano particles) into general solder, the composite electronic solder can be prepared, due to its role of solution or dispersion strengthening, and can improve the thermostable fatigue and creep properties of solder joint, it is also usually named as RCS (reinforced composite solder).Based on researchful analysis of RCS, such as metal particles, particles for high hardness, particles for low expansion coefficient, rare-earth particles and low aggregated particle, and of their reinforced mechanism, the technical requirements of RCS is found, it is also analyzed problems and application prospects of RCS.
Abstract: Thin films of transparent conducting aluminum-doped zinc oxide (ZnO:Al) were grown by rf magnetron sputtering technique using a sintered ceramic target of ZnAl2O4. The microstructure and optoelectrical properties of the deposited films were characterized wiyh XRD, four-point probe and spectrophotometer. The results show that the polycrystalline ZnO:Al films consist of the hexagonal crystal structures with c-axis as the preferred growth orientation normal to the substrate, and that the substrate temperature significantly affects the crystal structures and optoelectrical properties of the thin films. The ZnO:Al films deposited at the substrate temperature of 670 K has the relatively well crystallinity, the largest crystal grain, the highest transmittance and the highest figure of merit.
Abstract: Cutting pick is a kind of widely-used consumptive mining tool, however its body is easy to break in the mining producing process, the problem that pick body easy to break could be solved by using the warm extrusion forming techniques under the premise of without raising the material level. This paper mainly focuses on the structural characteristics and material technological properties of 42CrMo high-strength steel cutting pick body, and adopts the power balance principle got the approximation of the deforming force, and derived the approximate calculation formula of warm extrusion force for cutting pick body; and analyzed the temperature field, equivalent stress, strain field and metal’s flowing rate field of warm extrusion forming by adopting numerical simulation method, and verified the result with the experiment. The result shows that the material organization grains of cutting pick produced by the new technique could be refined; the pressing direction of cutting picks’ shape outline forms forging streamlines, the quality is good. In a word, this new technique could completely meet the requirement of cutting pick.