5083铝合金在400℃的超塑性变形行为和硬化特征

为研究5083铝合金在500℃以下的超塑性,在400℃进行了恒应变速率拉伸试验,获得了应变硬化指数n及应变速率敏感性指数m,分析了应变速率.ε对伸长率δ,n和m值的影响。结果表明:在400℃时5083铝合金可获得的最大伸长率为278%,对应的.ε=0.000 26 s-1,n=0.122,m=0.274;n随应变速率增大而减小,δ和m随应变速率增大先增大后减小,其中δ受应变速率影响显著。     

Electrochemical noise applied to the study of the inhibition effect of CeCl3 on the corrosion behaviour of Al-Mg alloy AA5083 in seawater

Electrochemical noise measurements have been used to study the corrosion behaviour of aluminium alloy AA5083 in 3.5% NaCl solution with and without doping with CeCl₃ at 500 ppm. Information on the evolution of corrosion activity over a period of 4 days and on the corrosion mechanism itself has been obtained for the two systems. Experimental data obtained have been analysed using robust statistical parameters and wavelet transform; transient shapes were also studied. The various mathematical techniques applied to analyse the electrochemical noise data have been proposed recently. This paper thus not only characterises the corrosion systems studied but also illustrates the usefulness of these new methods.     

5083铝合金热压缩流变应力曲线修正与本构方程

在Gleeble-3800热模拟机上采用等温压缩实验研究5083铝合金在变形温度为523~723K、应变速率为0.01~10s-1、真应变为0~0.7条件下的高温流变应力行为。基于热传导对合金变形热效应的影响,对流变应力曲线进行了变形热修正。结果表明:热传导对变形过程中产生的温升影响不可忽略,其影响随着真应变的增加而更加显著;修正后的流变应力对峰值应力影响不大,但稳态流变应力软化趋势得到一定程度的减弱。建立了Zener-Hollomon参数的本构方程,可对5083铝合金在不同变形条件下的流变应力进行预测,温升修正后的流变应力值与本构方程的预测值吻合较好,平均相对误差仅为5.21%。     

Processing,characterization, room temperature mechanical properties and fracture behavior of hot extruded multi-scale B4C reinforced 5083 aluminum alloy based composites

Microstructural characteristics and mechanical behavior of hot extruded Al5083/B₄C nanocomposites were studied. Al5083 and Al5083/B₄C powders were milled for 50 h under argon atmosphere in attrition mill with rotational speed of 400 r/min. For increasing the elongation, milled powders were mixed with 30% and 50% unmilled aluminum powder (mass fraction) with mean particle size of >100 μm and <100 μm and then consolidated by hot pressing and hot extrusion with 9:1 extrusion ratio. Hot extruded samples were studied by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), tensile and hardness tests. The results showed that mechanical milling process and presence of B₄C particles increase the yield strength of Al5083 alloy from 130 to 566 MPa but strongly decrease elongation (from 11.3% to 0.49%). Adding <100 μm unmilled particles enhanced the ductility and reduced tensile strength and hardness, but using the >100 μm unmilled particles reduced the tensile strength and ductility at the same time. By increasing the content of unmilled particles failure mechanism changed from brittle to ductile.     

Simulation of micromechanical damage to obtain mechanical properties of bimodal Al using XFEM

In this paper, we focus on the stress–strain behavior prediction of the bimodal bulk Al5083 series which are comprised of Ultra-Fine Grains (UFG) separated by Coarse Grain (CG) regions. This material is selected due to the availability of the required data in the literature. The CGs in the UFG matrix effectively prevents microcracks from propagation, leading to enhance ductility and toughness while the strength remains high. In this work, initially the dependency of stress–strain behavior of the model on the CG distribution in constant volume fraction is investigated by extraction of RVEs from optical microscopy (OM) images of the real material. Then, XFEM is implemented for bimodal materials considering various fracture criteria for brittle and ductile phases in maximum traction and cohesive law. The solution convergence of such a problem with irregular geometry, plasticity and crack initiation–propagation without any defined pre-cracks demanded extreme effort that accomplished by refining and arranging meshes and adding damage stabilizations. As a result of the above procedures, the sensitivity of the modeling procedure to various RVEs is obtained, the crack initiation–propagation pattern in microscale is predicted and consequently, the global stress–strain behavior result is obtained. It is shown that the predicted results are in good agreement with the available experimental results.     

Nanostructural and electrochemical characteristics of cerium oxide thin films deposited on AA5083-H321 aluminum alloy substrates by dip immersion and sol-gel methods

In this paper nano sized cerium oxide coating were applied by sol-gel and conversion (dip immersion) method on AA5083-H321 aluminum alloy. Nanostructural and phase properties of nano sized cerium oxides were investigated by SEM, EDX and AFM studies. Potentiodynamic polarization and EIS tests have been used to study corrosion behavior of nano sized cerium oxide films in 3.5% NaCl. Results indicated that cerium oxide which obtained by sol-gel method performed better corrosion and pitting resistance compared with dip immersion method.     

基于最大m值法的商用5083铝合金材料性能测试

采用最大m值法在450、475、500℃下测试商用AA5083合金材料性能,并与恒速度、恒应变速率法拉伸试验结果进行了对比分析.结果表明:该商用AA5083铝合金塑性较差,在450、475、500℃下恒应变速率、恒速度拉伸,伸长率普遍小于100％,超塑性不明显.采用最大m值法测试材料性能,其在450、475、500℃下伸长率分别为105％、107％、154％,但超塑性依然不明显.随着变形程度增大与温度的升高,该商用铝合金原始的长条状组织不断开始断裂并趋于变短,最后变成等轴组织.     

Non-destructive inspection for weld joint of steel structure

Friction stir welding (FSW) succeeded in producing high quality dissimilar welds with AA5083 and A6N01 by evaluation of the microstructure and the root bend testing. A6N01 with a wide optimum range of welding condition should be placed on the retreating side to weld a sound joint between AA5083 and A6N01. The optimum welding condition of FSW for the dissimilar alloys between AA5083 and A6N01 was wider than that of AA5083. In the opposite orientation, A6N01 on the advancing side can hardly flow into AA5083 on the retreating side in front of the tool. As the pores on inappropriate welding conditions were observed, large pores on a lower tool rotation speed were different from small discontinuous pores on a higher tool rotation speed.     

Evaluation of Vitreous and Devitrifying Enamels as Hot Forming Lubricants for Aluminum AA5083 Alloy

The adhesion of aluminum to tool surfaces during the hot forming of sheet aluminum alloys presents challenging tribological problems. Graphite and boron nitride are commonly used as aluminum adhesion mitigating solid lubricants for hot forming processes, but lubricant breakdown in high-stress areas, such as corners and bends, remains an issue compromising the quality of the formed parts as well as the tool life. Low-melting temperature enamels may provide an affordable and easy to apply alternative. In this study, vitreous (amorphous glass) and devitrifying (two phase crystalline glass) layers were deposited on the surface of sheet aluminum samples with a sedimentation technique. Enamel lubrication was effective in preventing aluminum transfer to the steel counterface. Hence, the prospect exists for the use of these enamels as aluminum workpiece lubricants in hot forming operations. This article was presented at Materials Science & Technology 2007, Automotive and Ground Vehicles Symposium held September 16-20, 2007, in Detroit, MI.     

5083铝壳艇外加电流阴极保护系统研制

在考察5083铝合金在海水中的电化学性能的基础上,得出了它的阴极保护电位和保护电流密度。并开展了5083铝壳艇外加电流阴极保护的码头实船试验和挂片试验,为这一技术的实际应用奠定了基础。