超声波功率对铸锭内的气孔及组织细化的影响

研究了超声波功率对铝合金铸锭内气孔的影响,同时也考察了超声波功率对铝合金铸锭组织细化的影响,分析了超声波对铝合金铸锭内气孔影响的原因。研究结果表明,超声波在金属熔体内产生的空化效应可分为亚空化效应阶段和发展-发达阶段,只有在发展-发达阶段才具有良好的除气效果。     

智能温度控制仪在铝电解铸造保温炉上的应用

简要介绍了KX-C智能温控仪的性能、特点;结合铝电解铸造保温炉的控制要求,阐述了KX-C智能温控仪对保温炉的恒温控制过程。应用表明,该仪器由于具有控制准确、动作灵敏、接线简单、无需校准、成本较低、可靠性高、无需维护等优点,可很好满足实际生产的要求。     

5 T有芯感应熔铝电炉熔炼铸造铝合金的实践

采用额定容量5t工频有芯感应熔铝炉，用电解铝液直接熔炼铸造铝合金，可提高劳动生产率、减,3-环境污染；生产的合金的化学成分均匀，同一熔次合金的主要化学成分硅的级差只有0．07个百分点，产品质量稳定；能源消耗低，交流电单耗为365kWh／t，比同类炉子低221kWh／t；2台5t有芯感应炉可实现年产1000t以上。     

3种高强铝合金的低温拉伸力学性能研究

利用拉伸测试、扫描电镜与透射电镜等手段,研究了2519-T87、2219-T81以及7039-T6三种铝合金板材的拉伸力学性能.结果表明,当变形温度由室温293 K降至77 K时,3种合金的屈服强度与抗拉强度均有所提高,其中抗拉强度分别提高23.1%、12.0%及6.2%.同时3种合金的伸长率随着温度降低有所提高.由于低温变形过程中平面滑移受抑制,加工硬化指数增加,变形均匀性增强,导致材料的强度增加,塑性有所提高.     

预拉伸对Al-Cu-Mg-Ag合金室温性能的影响

研究了时效前的预拉伸对高Cu/Mg比值的Al-Cu-Mg-Ag合金室温力学性能的影响.结果表明,预拉伸引起的位错促进θ′相的析出,同时位错在低温时效时不利于Ω相的析出,而高温时效则能够消除位错带来的不利影响.     

In-situ weld-alloying plasma arc welding of SiCp/Al MMC

Plasma arc welding was used to join SiCp/ml composite with titanium as alloying filler material. Microstructure of the weld was characterized by an optical microscope. The results show that the harmful needle-like phase Al4C3 is completely eliminated in the weld of SiCp/Al metal matrix composite（MMC） by in-situ weld-alloying/plasma arc welding with titanium as the alloying element. The wetting property between reinforced phase and Al matrix is improved, a stable weld puddle is gotten and a novel composite-material welded joint reinforced by TiN, AlN and TiC is produced. And the tensile-strength and malleability of the welded joints are improved effectively because of the use of titanium.     

铝板带轧制过程中的工艺润滑及影响因素

铝板带轧制工艺润滑不仅可以减摩降磨、节能降耗,而且可以改善轧后产品表面质量。在分析铝板带轧制工艺润滑机制的基础上,讨论轧制过程中润滑效果的影响因素,对铝板带轧制润滑工艺和润滑剂的改进有参考意义。     

两种空调用铝合金箔的性能对比研究

对8011和1100两种合金铸轧卷生产的空调箔,从化学成分、组织、性能等方面进行对比分析,进而从技术、经济方面确认铸轧8011合金坯料适宜生产高性能的空调箔。     

Preparation of ceramic coatings on inner surface of steel tubes using a combined technique of hot-dipping and plasma electrolytic oxidation

A new method for inner surface modification of steel tubes, named a combined technique of hot-dipping and plasma electrolytic oxidation (PEO) was proposed and demonstrated in this paper. In this work, metallurgically bonded ceramic coatings on inner surface of steel tubes were obtained using this method. In the combined process, aluminum coatings on steel were firstly prepared by the hot-dip process and then metallurgically bonded ceramic coatings were obtained on the aluminum coatings by PEO. The element distribution, phase composition and morphology of the aluminide layer and the ceramic coatings were characterized by SEM/EDX and XRD. The corrosion resistance of the ceramic coatings were also studied. The results show that, after hot-dip treatment, the coating layers consist of two layers, where Al, Fe_xAl _(1−x) were detected from external topcoat to the aluminide/steel substrate. Then after PEO process, uniform Al₂O₃ ceramic coatings have been deposited on inner surface of steel tubes. The ceramic coatings are mainly composed of -Al₂O₃ and γ-Al₂O₃ phase. The compound coatings show favorable corrosion resistance property. The investigations indicate that the combination of hot-dipping and plasma electrolytic oxidation proves a promising technique for inner surface modification of steel tubes for protective purposes.     

Influence of the Workpiece Stiffness on the Electromagnetic Sheet Metal Forming Process into Dies

Electromagnetic sheet metal forming is a high speed forming process using pulsed magnetic fields to form metals with high electrical conductivity such as aluminum. Thereby, workpiece velocities of more than 300 m/s are achievable, which can cause difficulties when forming into a die. The kinetic energy, which is related to the workpiece velocity, must be dissipated in a short time slot when the workpiece hits the die; otherwise undesired effects, for example rebound can occur. One possibility to handle this shortcoming is to locally increase the stiffness of the workpiece. A modal analysis is carried out in order to determine the stiffness of specific regions of the workpiece so that an estimation concerning the feasibility of the desired geometry is possible in advance without doing cost and time consuming experiments. Thereby, the desired geometry of the workpiece will be fractionized in significant sectors. This approach has to define the internal force variables acting on the cutting edge, which are required to constrain the numerical model. Finally, a method will be developed with the objective of calculating the stiffness of each sector. The numerical results will be verified by experiments. This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati, OH, October 15-19, 2006.