ADI风镐缸体铸件生产工艺改进

针对风镐缸体铸件存在的缺陷,分析了原铸造工艺及产生缺陷的原因,找出ADI风镐缸体铸件铸造过程中的难点,提出了改进工艺方案,并通过加强熔炼及热处理的操作规范性,减少了铸件缺陷的产生,提高了产品的质量和合格率,降低了生产成本.     

Electrical-discharge wire cutting of ADI and its effect on impact energies

This study built up a set of machining data for electrical-discharge wire cutting (EDWC) of austempered ductile iron (ADI). The treated ADIs with the optimum toughness and the superior strength and hardness were very difficult to machine by the traditional technique. The EDWC process was used to cut the specimens of ADI and the remelted layer and the heat affected zone of the cut surfaces were measured and observed. Optimum cutting conditions were suggested for ADIs with different nodular counts and/or with varying matrix structures. Experimental results showed that if ADIs are cut by EDWC, then the formation of microvoids due to the decarburization and vaporization of graphite nodules at the remelted layer greatly deteriorate the quality of the machined surface. A severe bubbling was observed during cutting. This bubbling in the pool of dielectric fluid markedly lowered the cutting feedrate of EDWC. A model was proposed to correlate the cutting feedrate with the thickness of the workpiece, the time of the discharge spark, the feedrate override of the table, nodule counts of irons and the per cent retained austenite of ADIs.     

Analysis of mechanical properties and its associated fracture surfaces in dual‐phase austempered ductile iron

This work aims at evaluating the fracture surfaces of tensile samples taken from a new kind of ductile iron referred to as ‘dual‐phase Austempered Ductile Iron (ADI)’, a material composed of ausferrite (regular ADI microstructure) and free (or allotriomorphic) ferrite. The tensile fracture surface characteristics and tensile properties of eight dual‐phase ADI microstructures, containing different relative quantities of ferrite and ausferrite, were studied in an alloyed ductile cast iron. Additionally, samples with fully ferritic and fully ausferritic (ADI) matrices were produced to be used as reference. Ferritic–pearlitic ductile irons (DI) were evaluated as well. For dual‐phase ADI microstructures, when the amount of ausferrite increases, tensile strength, yield stress and hardness do so too. Interesting combinations of strength and elongation until failure were found. The mechanisms of fracture that characterise DI under static uniaxial loading at room temperature are nucleation, growth and coalescence of microvoids. The fracture surface of fully ferritic DI exhibited an irregular topography with dimples and large deformation of the nodular cavities, characteristic of ductile fracture. Microstructures with small percentages of ausferrite (less than 20%) yielded better mechanical properties in relation to fully ferritic matrices. These microstructures presented regions of quasi‐cleavage fracture around last‐to‐freeze zones, related to the presence of ausferrite in those areas. As the amount of ausferrite increased, a decrease in nodular cavities deformation and a flatter fracture surface topography were noticed, which were ascribed to a higher amount of quasi‐cleavage zones. By means of a special thermal cycle, microstructures with pearlitic matrices containing a continuous and well‐defined net of allotriomorphic ferrite, located at the grain boundaries of recrystallised austenite, were obtained. The results of the mechanical tests leading to these microstructures revealed a significant enhancement of mechanical properties with respect to completely pearlitic matrices. The topographies of the fracture surfaces revealed a flat aspect and slightly or undeformed nodular cavities, as a result of high amount of pearlite. Still isolated dimple patterns associated to ferritic regions were observed.     

等温淬火球墨铸铁在汽车底盘悬架类零件上的应用

对某车型上底盘悬架类零件进行轻量化设计,由铸钢件改用等温淬火球墨铸铁件.通过对原材料、铸造和热处理等工艺过程的严格控制,力学性能稳定达到了ASTM A897/A897M-06 Grade 1050-750-7要求,并实现了小批量生产.从试制及装车路试情况来看,满足了所设计的性能要求,零件重量减少了39.6%,并在后续改进中,进一步增加等温淬火球墨铸铁件数量,整车的等温淬火球墨铸铁件重量达到了550.4 kg.     

ADI在我国铁路系统的应用及前景

详细介绍了ADI斜楔和衬套的主要技术指标及其在铁路车辆系统上的应用现状;同时介绍了内燃机车ADI气缸套和衬套的研发内容、所达到的技术水平、以及应用情况,并具体分析了内燃机车使用ADI气缸套和衬套所带来的巨大经济效益和社会效益.     

成立ADI工程公司的建议

分析了中国ADI产业化所遇到的困难,建议成立包括教育中心、推广中心、产业串联中心、应用工程研究中心、技术研发中心、规范与产品认证中心、国内外交流中心、国内外交易中心在内的中国ADI工程公司,以便更好地发挥全国ADI技术委员会的职能作用,推进中国ADI事业健康快速地发展.     

AUSTEMPERING OF A SILICON MANGANESE CAST STEEL

The influence of austempering on the microstructure and mechanical properties of an alloyed cast steel containing high silicon (3.00%) and high manganese (2.00%) was studied. The influence of microstructure on the plain strain fracture toughness of this new steel was also examined. The test results show that by using a suitable austempering process, i.e., by austenitizing at 1010°C (1850°F) for 2 hr and then subsequently austempering at 316°C (600°F) for 6 hr, it is possible to produce more than 80% austenite in the matrix of the material. Such a large percentage of austenite in the matrix made the steel almost nonmagnetic. Austempering resulted in a significant improvement in mechanical properties as well as fracture toughness of the material. The potential applications of this steel are in naval structural components, aircraft, and automotive components.     

二维ADI多域伪谱时域算法

针对时域有限差分算法和传统的伪谱时域算法稳定性不足的问题,提出了一种将ADI技术与多区域伪谱时域算法相结合的ADI-MPSTD算法,并采用紧凑矩阵形式对其进行清晰的描述．此算法不仅具有多区域伪谱时域算法分析任意曲边形体问题的精确性和灵活性,而且稳定性和效率也相应地提高．ADI-MPSTD的数值结果与传统的算法的结果相比,证明了该算法的高精度和良好的稳定性．     

Implicit methods for fluid dynamics

This paper represents the contributions to the development of implicit procedures for solving the equations of fluid dynamics made by Briley and McDonald (1975)[1], Beam and Warming (1976, 1978) [2] and [3] and Lombard et al. (1983) [4]. The contributions of Briley and McDonald and Beam and Warming are well known, but Lombard has not been fully recognized for his innovative contributions to flux vector splitting and use of the DDADI (Diagonally Dominate Alternating Direction Implicit) algorithm. Their contributions are presented herein.Fully implicit algorithms are applied to two complex flow problems of current interest, (1) hypersonic non-equilibrium flow about a blunt nosed body and (2) flow within an MFD (magneto-fluid dynamics) accelerator. These two applications would be exceeding costly without the use of fully implicit methods.     

奥贝球墨铸铁的接触疲劳与耐磨性能

结合起重机车辆的工况进行了奥贝球铁机械性能、接触疲劳性能和耐磨性能的试验表明,应用奥贝球铁代替ZG50SiMn制造起重机车轮是可行的.