Friction stir welding of aluminium casting alloys

The results of testing friction stir welding quality in relation to EN AC-43200 (AK9) and EN AC-45000 (AK64) aluminium casting alloys are presented. The test joints were made with the use of a welding machine constructed on the basis of numerically controlled milling machines. The assessment of the joint quality was made based on visual inspection, mechanical testing, weldment structure analysis and hardness tests. The purpose of the investigation was to discover the possibility of friction stir welding of casting alloys and the influence of welding conditions on joint properties and structure. The test results show good weldability of aluminium casting alloys by the FSW method. Sound welds can be obtained in a relatively wide range of welding parameters while the weld strength is satisfactory. In order to obtain the highest quality joints, the workpieces must be pressed onto the other, while the welding process cannot run with excessively high speed. The best mechanical properties of the joints were achieved when the friction process was conducted at a rotational speed of the mixing tool of 900 rpm.     

铝合金激光焊接的工艺特性及其发展现状

概述了铝合金激光焊接的工艺特性及难点,指出了铝合金激光焊接技术的研究现状及发展方向。     

铝合金电阻点焊研究现状及工业应用

铝合金作为一种新型节能材料,被广泛应用在航空航天、汽车工业等领域,其特点是低密度、高比强度、导热导电性能优异、抗腐蚀性强等.阐明了铝合金电阻点焊存在的难点,并进行了相关的原理性解释,归纳总结了国内外关于铝合金电阻点焊的相关研究现状,探讨未来铝合金的电阻点焊研究方向与研究重点,并列举了铝合金的电阻点焊在汽车工业与其他产业中的应用.     

两种铝合金的点焊组织模拟与试验分析

AA754和AA6082是两种具有不同强化机制的铝合金材料,在电阻点焊加热过程中,两种铝合金材料的组织会发生不同类型的转变.通过采用不同的计算模型,使用有限元软件对两种铝合金点焊后不同焊接组织的分布进行了模拟和预测.通过焊接试验研究,对两种铝合金的点焊组织的形态和分布进行了观察.结果表明,所采用的两种计算模型可以有效的预测和反映出两种铝合金点焊组织变化过程中的一些现象.仿真结果和试验结果都显示出两种铝合金的点焊组织有着明显不同的特征.     

Rational selection of semi‐finished products made from aluminium and magnesium alloys for welded structures

The results of investigation of the effect of various defects of welded joints on the fatigue resistance of welded joints are presented and used to normalize the defects taking strength characteristics into account.     

Optimization of the main parameters of resistance butt welding of large pressed profiles made of aluminium alloys

The main parameters of the conditions of resistance butt welding (RBW), influencing the stability of the melting process and the quality of the welded joints, are examined. Criteria for optimization of the RBW conditions are selected. The stability of the optimized conditions of RBW of large pressed profiles of aluminium alloys is analysed.     

Resistance spot welding aluminium to magnesium using nanoparticle reinforced eutectic forming interlayers

Successful joining of dissimilar metals such as Al and Mg can provide significant advantages to the automotive industry in the fabrication of vehicle bodies and other important components. This study explores dissimilar joining of Al–Mg using a resistance spot welding process to produce microstructurally sound lap joints and evaluates the impact of interlayer composition on microstructural evolution and the formation of intermetallic compounds within the weld nugget. The results indicated that mechanically sound joints can be produced, with fine equiaxed and columnar dendrites within the weld nugget. The presence of intermetallic compounds was also confirmed by the variation in the microhardness values recorded across the weld zone.     

Methods for reducing weld porosity in argon-shielded arc welding of aluminium alloys

Cause analysis of porosity in aluminium argon-arc welded joints is carried out, particularly that of aluminium–lithium alloy 1424. Feasible production methods of reducing the quantity of voids in the joints are considered.     

铝及铝合金焊接方法的概述与选择原则

阐述了铝及其合金的五个方面焊接性特点和相应技术难点,介绍了常见铝及其合金焊接的工艺方法、原理、特点及应用情况。为了使生产一线的技术人员了解有关高效铝及其合金的焊接技术,重点介绍MIG焊的技术特点、控制模式以及目前国内外热度关注的先进焊接工艺方法及特点。根据每种焊接工艺方法的技术难度、设备投资、质量保证、人员素质、劳动者强度、产品要求等特点,提出焊接方法的选择原则。     

Friction stir welding of aluminium lap joint by tool without probe

A friction stir welding process, with a rotating tool without a probe, was employed and applied to a lap joint of aluminium plate. The thickness of the aluminium plates was 0.5 mm. New tool shapes were developed. The tops of the tool were dome shaped. In this process, the rotating tool was plunged into the aluminium plate. The tool-rotating axis was vertical to the specimen surface, and then moved in the welding direction at a speed of 20 mm/s. Tool rotation speed was 18,000 rpm.

At tool plunge depths of 0.1 mm or over, it was possible to weld the two plates. At tool plunge depth of 0.1 mm, its joint was fractured at the weld interface. At tool plunge depth of 0.2 mm or over, the joints were fractured at the stir zone of the upper plate or the heat affected zone of the lower plate. Based on observation of the hardness profiles and the thickness change of the weld area, controlling factors of the joint strength are discussed.     

Metallurgical and technological porosity of aluminium alloys in arc welding

Repair welding experience for profound cutting at expensive part restoration of the primary large-tonnage cones shafted and fabricated from both low-carbon steel 45L and hard-to-weld steels 34XM1A is described.     

Evaluation of heat input during friction stir welding of aluminium alloys

Heat input is one of the key parameters governing the quality and service properties of friction stir welds. By using a calorimetric technique, the heat inputs generated during the friction stir welding of the aluminium alloys, 1100 and 5083, were measured over a wide range of welding parameters. An empirical equation to estimate the heat input using the welding parameters was established based on a multiple regression analysis of the results. The effect of the heat input on the final grain size of the stir zone was also investigated by the electron backscatter diffraction method. The quantitative relationships between the input variables, heat inputs, and final grain sizes in the stir zone were derived.     

Laser pressure welding of aluminium and galvannealed steel

Dissimilar metal joints of galvannealed steel and commercially available pure aluminium (A1050) sheets were produced by changing the laser power and the roller pressure by the laser pressure welding method. In this method, the YAG laser beam was irradiated into a flare groove made by these dissimilar metal sheets. In addition, the laser beam was scanned at various frequencies and patterns through the fθ lens using two-dimensional scanning mirrors. Then the sheets were pressed by the pressure rolls to be joined. The compound layers in the weld interface were observed by optical microscope, and the layer thicknesses were measured. The thicknesses were in the range of 7–20 μm. The mechanical properties of welded joints were evaluated by the tensile shear test and the peel test. In the tensile shear test, the strengths of the joints produced under the most welding conditions were so high that the fracture occurred through the base aluminium sheet. In the peel test of the specimens subjected to the laser beam of 1200–1400 W power under the roller pressure of 2.94 kN, the specimen fracture took place in the base aluminium sheet. Even if the compound layer was thick, high joint strength was obtained. In order to know the reason for such high strength of joints with thick compound layers and the joining mechanism, the compound layer was observed by the HR-TEM. The TEM observation results revealed that the main phase in the compound layer was the solid solution of Al + Zn. Moreover, the intermetallic compound was identified as FeAl, Fe₂Al₅, Fe₄Al₁₃, and Fe₂Al₅Zn_0.4 phase by electron diffraction. The Fe₃Zn₁₀ (Γ phase) of Fe–Zn intermetallic compound was confirmed on a Fe base material. It is assumed that the joining areas were heated in a range of 782°C more than 665°C, a melting point of Al, by laser irradiation because the δ_lk phase aspect was not confirmed. Because the surfaces of A1050 and Zn plated layer were melted thinly, the layer was over 10 μm thicker. The reason for the production of high strength joints with the relatively thick intermetallic compound layer was attributed to the formation of (Al + Zn) phase with finely dispersed intermetallic compounds.     

Ultrasonic welding of heat-treatable aluminium alloy A6061 sheet

In this study, the authors applied the ultrasonic welding method to weld A6061 heat treatable aluminium alloy and investigated the effects of clamping load and welding time on the properties of the weld. In addition, in order to improve the strength of the joint, the effectiveness of the ethanol droplet on the faying surface was examined. The following results were obtained.

The joint strength increased with clamping load and welding time. The fracture of the joint produced under the welding conditions of 1176 N clamping load and 1.5 s welding time occurred in the base metal. The ethanol droplet on the faying surface successfully produced the joint with a strength equivalent to that of the base metal under the welding conditions of smaller clamping load and shorter welding time than the case without ethanol droplet. The softening around the welded area that was performed with the ethanol droplet was smaller than that in the welded area produced by other methods such as TIG and friction stir welding. The fracture surface of the joint welded with the ethanol droplet was remarkably irregular and rough. A dimple pattern was observed over a wide area, indicating that the welded area was significantly expanded. The ethanol droplet made the temperature of the weld area higher than that without ethanol, resulting in improved joint strength with an increase of the plastic deformation at the interface.     

Friction welding of T-joints in sheet structures of aluminium alloys

A special tool is developed for the friction welding of T-joints which produces T-sections with smooth contact between the surfaces of the web and the flange.     

Welding of aluminium alloy by using filler-added laser-arc hybrid welding process

Laser-arc hybrid welding is considered to be an efficient, practical welding process because its deposited metal from welding wire can increase gap-bridging ability and prevent welding defects such as undercutting or underfilling. The deposition rate from welding wire, however, cannot be adjusted independently on the welding current under the stable welding conditions because it is necessary to maintain a constant arc voltage. Although the combination of a higher deposition rate and a lower welding current is sometimes needed, for example during the welding of a thin sheet, a high deposition rate generally accompanies with a high welding current in the conventional laser-arc hybrid welding. In order to solve the above-mentioned problems, the authors have proposed a novel method, a filler-added laser-arc hybrid welding (FLA welding) process, to increase a deposition rate without increasing the welding current itself in the welding of aluminium alloy. As a result, gap-bridging ability can be increased in the welding of both thin and thick plates. In this paper, the welding of aluminium alloy butt joints by using FLA welding process is discussed.     

5A02铝合金C O2激光焊接头组织和力学性能分析

对2mm厚的5A02铝合金进行C02激光焊接试验研究.分析激光焊缝成形和接头微观组织形态,测定了接头上表面和焊缝厚度方向上的维氏硬度,并对接头进行横向和纵向拉伸试验,用扫描电镜观察分析拉伸断口形貌.结果表明,激光功率和焊接速度合理匹配能够获得成形良好、无缺陷的焊缝,焊缝中部为等轴细晶,熔合线附近是柱状晶组织.焊缝各区域...     

Material flow and void defect formation in friction stir welding of aluminium alloys

An ingenious experimental programme by combining artificially thickened oxide layer as marker material and ‘stop-action’ welding were used to study the material flow and defect formation in friction stir welding of aluminium alloys. The results showed that material flow around the pin on the advancing side (AS) was severer than that on the retreating side (RS) and the fastest velocity of material flow in the middle stir zone (SZ) was 43.9?mm?s^?1. Moreover, the material under the RS shoulder included extruded metal only and the material under the AS shoulder included extruded and rotated metal. Lastly, instantaneous void occurrence and insufficient inflow material were reasons for the preferential formation of void defects in the top SZ on the AS.     

Effect of backing runs on the properties of welded joints in aluminium–lithium alloys

The effect of the parameters backing runs and the composition of filler material on the properties of a welded joint and the heat-affected zone is investigated. It is shown that the porosity of the weld metal in the areas with backing runs depends strongly on the welding conditions, and when using Sv-1557 wire, the strength and plasticity are higher than those of the Sv-AMg6 wire.     

Welding aluminium alloys with nanobeam electrodes

Investigations were carried out to develop a technology for manufacturing and application in welding aluminium alloys ‘beam’ electrodes containing as modification agents nanopowders of high-strength refractory chemical compounds. Consequently, the grain growth of the structure of the welded joint is prevented and the mechanical properties of the welded components are improved.