A study of fusion zone microstructures of arc-welded joints made from dissimilar aluminum alloys

Arc welding has proven itself to be an economically affordable and efficient method for the joining of a wide variety of aluminum alloy structures that find extensive use in the industries of ground transportation and building construction. Welded joints, having a “T” configuration, in dissimilar aluminum alloys were produced using the semiautomatic arc welding process. In this study, a combination of a non-heat-treatable aluminum-magnesium alloy and a heat-treatable aluminum-magnesium-silicon alloy was successfully welded. Optical microscopy was used to characterize the fusion zone microstructures of the fillet-welded T joints. The intrinsic microstructural features and the development and presence of defects are highlighted.     

5083铝合金铸锭均匀化处理对铸锭和板材组织与性能的影响

系统研究了5083合金铸锭均匀化处理和不均匀化热处理对铸锭、成品板材组织和性能的影响。通过高温瞬时试验、剥落腐蚀试验、扫描电镜及力学性能试验,对经均匀化和不经均匀化的5083铝合金铸锭的轧制制品进行对比分析。     

固溶热处理对5083F铝合金耐腐蚀性能的影响

用5083F铝合金制造的船舶在海洋环境中以高速或高流速等状态运行时会受到少量腐蚀,适当的热处理可改善其耐腐蚀性能。通过硬度、转折电位、不同时效时间下的阴极极化电流密度及慢应变速率试验找到了防止腐蚀的最佳热处理条件,即在420℃下加热样品30 min,然后在水中冷却;最佳时效条件是样品在180℃下时效240 min。在海水中的慢应变速率试验(SSRT)显示,最佳条件下热处理略降低了试样的强度,但增加了伸长率和断裂时间,热处理提高了其抗腐蚀性能。     

Study and evaluation of abrasive water jet cutting performance on AA5083-H32 aluminum alloy by varying the jet impingement angles with different abrasive mesh sizes

This article describes the experimental investigation of abrasive water jet (AWJ) cutting on AA5083-H32 aluminum alloy. In this study, the influence of varying the jet impingement angles and abrasive mesh sizes with different water jet pressures, on the output parameters for the AWJ cutting of the aluminum alloy, was analyzed. The experimental results found that the output parameters, namely, the depth of penetration, top kerf width, kerf taper ratio, surface roughness, and abrasive contaminations, were strongly influenced by the combined effect of oblique jet impingement angles and abrasive mesh sizes on AWJ. Also, it is noticed that oblique jet impingement angles have more influence on the output cutting responses than the normal jet impingement angle, and consequently, each abrasive mesh size has an influence on the different output responses for the AWJ cutting of AA5083-H32. Scanning electron microscope and microhardness tester were used to examine the different cutting regions of the kerf wall surfaces. The Energy-dispersive X-ray spectroscopy analysis was used to confirm the amount of silicon particles embedded in the AWJ cut surfaces. The adequacy checking of the experimental data for the AWJ cutting performance models has been analyzed through the residual plots using the statistical software.     

Role of intermetallic phases in localized corrosion of AA5083

The presence of intermetallic inclusions very often plays a crucial role for the susceptibility of different aluminium alloys to localized corrosion attack. The intimate details of localized corrosion of 5083 aluminium alloy have been studied in the present work. Local techniques such as scanning Kelvin probe force microscopy, in situ atomic force microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy were used to investigate the mechanisms and the kinetics of localized corrosion attack. The importance of iron-rich and Mg₂Si intermetallic phases in the initiation of corrosion processes is demonstrated in the paper.The Mg₂Si phase has a potential lower relatively to the matrix. Moreover, the high reactivity of magnesium leads to the dissolution and consequently to the fast dealloying of these intermetallics. However, hydroxide (Mg(OH)₂ and SiO₂·nH₂O) deposits formed during corrosion act as an additional diffusion barrier hindering the deep propagation of pits.The iron containing intermetallics have the potential higher with respect to the aluminum matrix playing the role of effective cathodic centers for oxygen reduction causing anodic polarization and pitting in the surrounding alloy matrix. Dealloying of such intermetallics with subsequent iron enrichment was also revealed. Pitting initiation seems to be statistical and independent of the composition of Fe-rich intermetallics. However, the active growth of the pits prevents initiation of localized corrosion attack in nearby sites. A new pit can start to grow only when a neighbor one becomes passivated.     

超塑性差温拉深与整形复合工艺数值模拟与试验

采用热一力耦合数值模拟与试验结合,研究超塑性差温拉深与整形复合工艺.计算大拉深比支架件初始毛坯;建立AA5083材料随温度变化的粘塑性本构关系,经子程序将其植入MARC软件模拟;依据模拟结果,制造2套模具并成形了合格零件.超塑性差温拉深的凹模温度为525℃,即此材料最佳超塑性温度,凸模内部通水冷却;整形过程温度亦为525℃.结果表明,成形支架厚度分布均匀,与模拟结果吻合良好.     

5083的激光传导焊接

研究了利用高能量的二氧化碳和YAG激光器作为于激光传导焊接2mm～3mm板厚的AA5083。结果表明,焊接2mm～3mm板厚的AA5083时产生的粗大的焊接区并充分渗透。通过观察,在这个过程中渗透深度最初开始增加并达到最大值,然后随着斑点大小的增加而逐渐减小。     

Digital modelling of the galvanic corrosion behaviour of a self–piercing riveted AZ31 ‐ AA5083 hybrid joint

This study focuses on the corrosion phenomena occurring between aluminium AA5083 and AZ31 magnesium sheets, joined with a coated steel self‐piercing rivet, by punch rivet technology. These assemblies were studied by immersion tests and scanning vibrating electrode technique (SVET) in sodium chloride solutions, in order to evaluate the effects of joint geometry on corrosion resistance. The observed results were also used for validation of transient finite element method (FEM) simulations. A fully coupled continuum model was used to compute the evolution of electrochemically and chemically induced corrosion attack, formation of corrosion products and their influence on the overall system kinetics. Additionally, X‐ray diffraction (XRD) analysis of the corrosion products provided evidence for the formation of layered double hydroxides (LDH), which is in accordance with the model outputs. The current study targets the optimization of joint setup for corrosion resistance. The suitability of corrosion simulation for the AZ31‐AA5083‐Almac ternary galvanic system is shown alongside. The developed modelling approach represents a step forward in terms of digital service‐life assessment of multi‐material joints.     

Silane based field level surface treatment methods for aluminium,titanium and steel bonding

Grit blast silane and AC-130 sol–gel treatments were tested to assess their performance in aluminium, titanium and stainless steel structural epoxy bonding. Static single lap shear and static double lap shear specimens were tested as dry and wet at room temperature. Wedge tests were performed in a hot and wet exposure and in hot fresh water and salt water immersions. Acceptable field level methods were found for unclad and clad 7075 aluminium bonding without primers. With titanium and stainless steel, the use of a BR 6747-1 primer was found to be necessary for durable adhesion. In a case study, AC-130 sol–gel without a primer on naval grade 5083 aluminium provided good results also when immersed in Baltic Sea water.