Use of the gold markers method to predict the mechanisms of iron atmospheric corrosion

Iron corrosion under atmospheric conditions has been investigated by using the gold markers method. The corrosion experiments were performed in a climatic chamber with an accelerated treatment. The gold markers localization, carried out by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, revealed that the rust layer growth was essentially due to an internal development. Moreover, microRaman mappings allowed prediction of the mechanism of rust layer evolution during the ageing treatment. Finally these results were compared to samples corroded for several 100 years in order to extrapolate our observations to long term corrosion.     

难加工材料复合振动挤压攻丝工艺及设备研究

根据钛合金的性能,分析了钛合金攻丝的难加工性及挤压攻丝代替切削攻丝的可行性,并在此基础上研制了适应于难加工材料小螺纹攻丝的复合振动挤压攻丝机。新型振动攻丝机采用数控技术,实现了攻丝靠模通用化,具有周向和轴向振动功能,满足振动挤压攻丝新工艺的要求。     

KFC铜合金引线框架带材的连续挤压制造技术

针对目前KFC铜合金引线框架带材主要生产方法中存在的生产工艺流程长、设备投资大、产品成品率低和成本高等问题,提出KFC铜合金引线框架带材的连续挤压制造技术,并通过企业的生产运行,验证了该方法的技术可行性和工艺可行性,使企业的产品生产效率、质量和品种等多方面水平得到提高,尤其具有良好的节能减排优势.     

铝合金地铁车辆系统动力学特性仿真

地铁车辆系统要求具有良好的动力特性。运用多体系统动力学分析软件ADAMS/Rail建立了铝合金A型地铁动车系统动力学分析模型,进行了稳定性、平稳性和曲线通过能力仿真计算,依据相关标准比较全面地分析其动力学特性。结果表明,该车蛇行运动临界速度远大于车辆设计速度,并且其平稳性和曲线通过能力良好,可满足运行要求。     

中镍铬合金铸铁的激光熔覆修复研究

本文是利用转镜扫描技术得到的线光斑对中镍铬合金铸铁窄带激光熔覆,为了减少试验次数,并排除不必要的试验参数,用正交试验法对激光熔覆处理效果的最大影响因素(P、V、B或D)进行试验方案设计.最后对试验结果进行分析比较获得最佳工艺参数.     

金属型重力铸造条件下的铝合金铸件生产技术

为了可靠提高铝制铸件产品的性能和品质,基于金属型铸造热交换的特点,通过制定金属型铸造工艺规范、调整涂料配方等技术方案,控制金属型的预热及上下型的温差、浇注温度与开模时间等工艺参数,达到了提高金属型使用寿命和铸件品质的目的。     

铸造钢锭工艺的研究

使用电弧炉熔炼生产钢锭的过程中,通过对材料准备、熔炼工艺过程中的注意事项以及具体操作的描述,总结了一套成熟的工艺流程,应用此流程进行了多类钢种的钢锭生产,较高程度的满足锻造专业公司的生产,在我公司范围内形成了一个自给自足的生产链。     

Influence of Ni concentration and deposition potential on the characterization of thin electrodeposited Zn–Ni–Co coatings

The electrodeposition of Zn–Ni–Co alloys from sulphate electrolytes was studied on steel rod. In order to elucidate the characteristics of the layer formation, a complementary approach was used based on the combination of various electrochemical techniques. The cyclic voltammetry and galvanostatic techniques for electrodeposition, while potentiodynamic polarization resistance and anodic linear sweeping voltammetry techniques were used for corrosion study. Under the examined conditions, electrochemical and surface analysis indicate that the deposition has taken place with the formation of three structures have a composition corresponding to pure Zn, γ-Ni₅Zn₂₁ and pure Co phases. The influence of nickel concentration as well as the effect of potential on the surface appearance and the deposits composition was examined. Under these experimental conditions the electrodeposition of the alloys is of anomalous type. The results indicate that the addition of Ni to the Zn–Co alloy, Zn–Ni–Co alloy formed which is more corrosion resistance than Zn–Co alloy. Also, the amount of γ-phase increased and the amount of pure Zn decreased with the increase of nickel concentration in the bath. The corrosion resistance of the zinc–nickel–cobalt alloy had been improved with the more concentration of nickel. The Ni content in the deposition layer had been increased at high deposition potential, whereas, pure Zn deposition had been decreased.     

Numerical and experimental investigation of cold rotary forging of a 20CrMnTi alloy spur bevel gear

Due to the complex three-dimensional (3D) geometry and tooling design, mass production of precision spur bevel gears by machining or conventional forging technology is impeded by numerous stubborn barriers to date. Cold rotary forging, an innovative incremental metal forming process, has great potential to improve the current situation owing to its flexibility and low tool load requirement. In the present study, a sound 3D rigid-plastic finite element (FE) model of cold rotary forging of a 20CrMnTi alloy spur bevel gear is developed under the DEFORM-3D platform. To ensure the precision of the proposed FE model, a series of experiments are well performed for the identification of the mechanical properties of 20CrMnTi alloy and the realistic friction conditions prevailing at the die-workpiece interface. By utilising this FE model, the workpiece geometry is optimised with the intention of achieving a better filling of gear shape and a lower forming load requirement, and then the distribution of different field-variables such as flow velocity and effective strain are thoroughly investigated. For verification purposes, the cold rotary forging experiments of 20CrMnTi alloy spur bevel gears are subsequently conducted. Good agreement between the experimental results and the simulation ones is highlighted by comparing the gear shape after cold rotary forging and the axial forging force, which validates employed model.     

Gap-free fibre laser welding of Zn-coated steel on Al alloy for light-weight automotive applications

As a result of new policies related to global warming announced by the European Union, avoiding unnecessary energy waste and reducing environmental pollution levels are becoming a major issue in the automotive industry. Accordingly, the lap welding of Zn-coated steels process, which is commonly used for producing car doors, has been gradually developed to lap welding of Zn-coated steel to light materials, such as Al alloy, Mg alloy and composite materials, in order to effectively reduce the vehicle weight. In certain part of car manufacture, organic glues are used to temporally join the Zn-coated steels and Al alloys before permanent welding takes place. The stability of such temporary joining by glues needs improving. Laser “stitching” or low strength welding could be considered as an alternative. However, challenges exist in joining Zn-coated steel on Al alloy by laser welding, due to significant differences of material properties between the two welding materials. Porosity, spatter and intermetallic brittle phases are readily produced in the weld. In this study, the effects of welding speed, laser power, number of the welding passes and type of shielding gas in gap-free welding of Zn-coated steel on Al alloy were investigated using a 1 kW single mode continuous wave fibre laser. Results show that a weld with higher shear strengths in the laser stitching application and less intermetallic phases could be obtained when nitrogen gas was used as the shielding gas. The corrosion resistance and the surface finish of the weld could be improved in double pass welding, especially when argon gas was used as the shielding gas.