Key Engineering Materials Vol. 584

Abstract: In the present work, effect of adding small amount of Y on the microstructure, physical and mechanical properties of Sn3.0Ag0.5Cu solder has been investigated. The purpose is to understand if the heavy rare earth Y has similar effect as light rare earth Ce or La on improving properties of SnAgCu lead-free solder. The results indicated that adding small amount of Y can evidently improve the wettability, mechanical strength and creep rupture life of the Sn3.0Ag0.5Cu solder alloy. It is pointed out that proper Y content in the Sn3.0Ag0.5Cu solder alloy should be in a range of 0.05~0.25wt%. Moreover, It is felt that the increase in mechanical strength may be related to the refining of IMCs of the solder due to the addition of small amount of Y.

Abstract: The ergonomic design of forest fire helmet is closely related to its safety performance. In order to improve the performance of forest fire helmet, three representative forest fire helmets are evaluated from the shape, material, safety, comfort and other aspects and analyzed according to the firemens usage condition. Some suggestions for helmet design, such as using suspension system, installing height adjuster, using adjustable goggles with peripheral knobs and decomposition using helmets, goggles and masks, are proposed, which provide a referential technical guidance for the design of forest fire helmets in the future.

Abstract: In this study, we firstly developed a numerical electrochemical micro-machining (EMM) setup. Furthermore, the effects of five vital process parameters, applied voltage, electrolyte type, electrode shape and diameter, electrode feed rate on micro-seams machining accuracy and process stability were evaluated. The experimental results show that: Wire electrodes machining accuracy is higher than that of sheet electrode. With the wire electrodes diameter decreased from 0.2mm to 0.06mm, micro-seam width is reduced by 36.55%. With the wire electrode feed rate increased from 0.2mm/min to 0.6mmm/min, micro-seam width is reduced by 44.2%. Sheet electrodes machining stability is better than that of wire electrode. The number of machining stability of sheet electrode is 25% higher than that of wire electrode in the condition of 8V applied voltage.

Abstract: The method to measure the cutting speed when high speed milling nickel alloy Inconel 718 based on semi-artificial thermocouple. The cutting parameters, tool wear and so on the cutting temperature were analyzed. The tests showed that the temperature was gradually increased with the increase of cutting speed. The cutting speed must be more than 600m/min, when the ceramic tools would perform better cutting performance in the high-speed milling nickel-based superalloy. In order to achieve more efficient machining, milling speed can be increased to more than 1000m/min. The impact amount of Radial depth of cut and feed per tooth were relatively small.

Abstract: This subject is proposed via authentic market investigation, based on the sharp increase of household garbage in urban cities and urgent demand for environmental amelioration in recent years. Taking horizontal refuse compactor as an example, this paper optimizes the configuration of key components of refuse compactors, by employing Finite Element Analysis (FEA) method, aiming to select the most appropriate components to equip compactors, whose operation efficiency can be markedly enhanced. The statics analysis for each key component is individually conducted by applying ABAQUS, the FEA simulation software, to test the reliability of this new structure.

Abstract: The cover is one of the key components of carding machine and its structural parameters play an important role for the carding quality and yield. In this paper, the force of the designed cover is analyzed when the cover into the carding zone, to obtain the stress and strain distribution of the cover in the whole carding process, based on the finite element analysis software ANSYS Workbench. The research not only examines the stiffness and strength properties of the cover, but also provides a theoretical guidance for the future structure design and parameter optimization.

Abstract: Ti-6Al-4V alloy was hydrogenated at 800°C by thermohydrogen treatment technology. Sliding friction and wear tests were carried out in a special device assembled on CA6140 turning lathe to investigate the friction and wear mechanism between hydrogenated titanium alloys and WC-Co cemented carbide. The morphological analyses of the worn surface were made by scanning electron microscope (SEM) and the diffusion and chemical reaction behavior of elements were analyzed by X-ray energy dispersive spectrometer (EDS). It was found that the main wear mechanisms of the unhydrogenated alloys were abrasion and adhesion and surface fatigue, while the main wear mechanisms of the hydrogenated alloys were abrasion and adhesion. The main wear mechanisms of the cemented carbide were all serious adhesion and spalling, and the specific wear forms were closed related to hydrogen contents. There are all not the chemical reaction wear and element diffusion wear in the friction region of whether the unhydrogenated alloys or the hydrogenated alloys or cemented carbide.

Abstract: Large cylindrical shell is a large diameter and thick wall tube part working in high temperature and high pressure environment. It is made of 2.25Cr-1Mo-0.25V high strength steel, whose machinability is special. The characteristics of cutting temperature and cutting force are researched in the cutting process by analyzing the machinability of 2.25Cr-1Mo-0.25V steel in this paper. And the main tool failure modes are analyzed in the cutting process, combining with empirical approach to compare tool failure modes under cutting different steels. The high efficiency cutting measures are proposed in tool optimization design finally, in order to provide a reference for high efficiency machining of large cylindrical materials.

Abstract: Speed control is the core problem of cutting machine design, the past has been the experience of adjusting the cutting speed, the lack of theoretical basis, randomness. In view of this, according to the basic requirements of cutting efficiency maximization, deduces the removal rate and feed speed, time equation, solving the cutting efficiency problem exists in the design of machine, and established when the removal rate is constant, relation curves of shear rate and time. Use of the method of cutting machine design, can improve the accuracy and scientific design, has higher application value.