Applied Mechanics and Materials Vols. 644-650

Abstract: In this paper, dynamic mechanical property tests under different tempreture and strain rate of high strength steel 18NiC250 are conducted by means of Hopkinson pressure bar technique. The results of tests show 18NiC250 steel is not only very sensitive on strain rate, but also sensitive to temperature. The rate relative constitutive model of this steel is obtained and well predicts dynamic mechanical property after yielded.

Abstract: To improve the wear properties of AZ91D magnesium alloys, a AlFeCuCoNiCrTi_1.5 high entropy alloy (HEA) coating was fabricated on AZ91D magnesium alloys by laser cladding using mixed powders of Al, Fe, Cu, Co, Ni, Cr, and Ti. The microstructure of the HEA coating was characterized by OM, SEM, and XRD. The wear resistance of the HEA coating was evaluated under dry sliding wear test condition at room temperature. The results show that the HEA coating mainly consists of a simple BCC solid solution phase. The HEA coating exhibits excellent wear resistance. The main wear mechanisms of the HEA coating and the AZ91D substrate were different, the former dominated by oxidative abrasive wear and the latter suffered from both adhesive and abrasive wear.

Abstract: The metallographic observation, thermo-simulation test and quantitative statistics were used to investigate the grain growth on different parts of the samples for Fe-40Ni-Ti alloy. The experiment results demonstrate that: near the center of the sample corresponding to the summit point of the temperature, the grain grows rapidly in 5s when the temperature reaches 1350°C, whose size is about 180μm; While the grain size of parent metal and HAZ (4mm to the welding line) remains nearly unchanged, whose size is about 80μm. The size of TiN particles in the welding line is fine than that of the parent metal obviously and the hinder to the grain boundaries can be observed. With the aid of Fe-40Ni-Ti alloy, the austenitic grain growth in the steel can be simulated.

Abstract: According to the arrangement of laminar cooling equipment in Desheng 1150mm hot strip mill, two-dimensional finite difference method has been used for coiling temperature online control model basing on the analysis of heat transfer characteristics, practical data are used to optimize water heat coefficient for self-learning as amended, this model are used to calculate the steel temperature change and distribution in the process of laminar cooling. Analysis of different cooling strategies on the cooling rate and organization of steel show that: In the same number of opened cooling tubes, the cooling capacity is not the same in the different strategies, the cooling to back direction is the strongest, followed by intermittent cooling, the cooling to front direction is the smallest. Cooling strategy was applied to the scene and simulated results match with the actual observation. The system has a wide range of cooling rate adjustment, the operation and control is well, which meet to the development and the requirements of new varieties.

Abstract: The tribological properties of TiN coating were studied at the speed of 40m/min-120m/min, under the load of 5N-15N at elevated temperatures between 200°C-600°C. It can be concluded that when the temperature is lower than 400°C, the coefficient of friction increased with temperature, but the value decreased because of the friction oxidation at 600°C.The wear mass loss of the coating increased with increasing of speeds and loads, and this proved the TiN coating was not adaptable to high temperature environment. The wear mechanisms of TiN coating at elevated temperature were abrasive wear, plastic deformation, oxidation wear and adhesion wear.

Abstract: EPC process, based on the casting structure, technical requirements, production volume, production conditions determines the casting solution, process planning. In this paper, the author from three aspects , the analysis of die casting process design principles, design principles and infiltration technology, makes a deeper understanding on the EPC process, and put forward some standards and requirements of the EPC process technology, which avoid the casting defects and waste caused by technical factors.

Abstract: The high-speed cutting is an advanced manufacturing technology with efficient, high quality and low consume, it is also the development direction of cutting. The concept and characteristic of high-speed cutting is discussed. The performance and application of the major tool materials (such as ceramic cutting tools, diamond tools, CBN tools, coated tools) for high-speed cutting is described. At last, the paper discusses the developing prospect and research direction for high-speed cutting tool materials.

Abstract: The carbon template was prepared by pyrolysis with different heating rate. The weight loss and anisotropic shrinkage of carbon template was calculated. The morphology and microstructure of carbon were characterized by scanning electron microscopy. The results suggest that the heating rate has evident effect on surface shape of carbon template, but little effect on weight loss and anisotropic shrinkage of carbon template.

Abstract: A method of molten salt replacement was used to prepare an Al coating on Mg-Li alloy at different temperatures. The thickness, microstructure, phase composition and corrosion electrochemical analysis of the coating treated at different temperatures were analyzed. The corrosion resistances of the specimens with and without optimal coating were comparatively evaluated. Results show that, the optimal treatment temperature is 350 °C, at which a thickness of 9.15 μm coating is formed. In the Al coatings, Al exists as the form of Mg₁₇Al₁₂ and AlLi. The corrosion resistance is much better than that of the specimen without coating.

Abstract: In this article, through the rapid development of badminton, detailed introduces the evolution process of badminton racket, through the use of the badminton racket composites badminton flying speed, also become more and more wonderful and exciting game.