Microstructural and mechanical characterization of electron beam welded Al-alloy 7020 (original) (raw)
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Characterisation of electron beam welded aluminium alloys
Science and Technology of Welding and Joining, 1999
2024 and 6061, were butt welded by autogenous electron beam (EB) welding. The fusion welding of alloy 5005 is not Electron beam (EB) welding was performed on three expected to present any major difficulty. The formation of diVerent aluminium alloys, namely alloys 2024, 5005, porosity may be the only concern in the welding of this and 6061 (plate thickness 5 mm except alloy 5005 alloy. On the other hand, the base metal mechanical which was 3 mm in thickness), to establish the local properties may be degraded in autogenous welding of alloys microstructure-property relationships that would 2024 and 6061. Furthermore, alloys 2024 and 6061 are both satisfy the service requirements for an electron beam crack sensitive alloys, and thus are more difficult to fusion welded aluminium alloy component with weld zone weld.1-4 However, the high thermal gradient from the weld strength undermatching. Microstructural characterinto the base metal in the low heat input EB process isation of the weld metals was carried out by optical creates very limited metallurgical modifications, and crack and scanning electron microscopy. A very low level sensitivity is therefore reduced. Owing to the low heat input, of porosity was observed in all EB welds owing the heat affected zone (HAZ) produced in EB welding is to surface cleaning before welding and the vacuum very narrow,5 and thus the problems associated with the environment of the EB welding process. Extensive HAZ are limited. However, as a result of the very high microhardness measurements were also conducted in temperatures experienced in the fusion zone, the loss of the weld regions of the joints. Global tensile properties some elements, for example vaporisation of magnesium, and f racture toughness properties (in terms of crack occurs during EB welding. The loss of such strengthening tip opening displacement, CT OD) of the EB joints were elements may degrade the mechanical properties of the determined at room temperature. T he eVects of strength welds by affecting the weld pool chemistry;6,8 also, in this mismatch and local microstructure on fracture case the strength of the fusion zone cannot be restored to toughness of the EB joints are discussed. T he purthat of the base metal by post-weld heat treatment. Several pose of the present paper is to report the partial researchers6,8-15 have reported the loss of alloying elements results of the European Brite-Euram project ASPOW in the welding of aluminium alloys. A common way of (assessment of quality of power beam weld joints; partially restoring the mechanical properties of the weld BRPR-CT 95-0021), which has been undertaken region is by the use of adequate filler alloy during welding. predominantly by industrial companies to establish The loss of strength in the fusion zone will cause a strain a European f ramework for destructive and nonconcentration in addition to the geometrical strain condestructive testing and assessment criteria for laser and centration that occurs if such a weld is exposed to an electron beam welds of over 20 metallic materials. external loading. Confined plasticity development within the undermatched EB weld zone will therefore reduce the Dr Ç am, Mr Ventzke, Dr Dos Santos, and Dr Koçak plastic straining capacity of the weld joint under tensile are at the GKSS Research Center, Institute of loading, as well as increasing the constraint within the Materials Research, Max-Planck-Strasse, D-21502 weld zone.16 An increase in constraint owing to confined Geesthacht, Germany, and Mr Jennequin and Mr plasticity may cause a reduction in the fracture toughness Gonthier-Maurin are with CNIM, Zone Industrielle of the sandwiched fusion zone, compared to an 'all fusion de Bregaillon, BP 208, F-83507 L a Seyne-Sur-Mer zone' compact tensile (CT) specimen. Of course, such an Cedex, France. Manuscript
Experimental investigation of electron beam welding of AA1350 aluminum alloy
Aluminum's unique properties, e.g. light weight, high strength, and resistance to corrosion, make it an ideal material for use in conventional and novel applications. Aluminum has become increasingly used in the production of aerospace equipment, automobiles and trucks, packaging of food and beverages. However it suffers from poor joint strength when welded by conventional fusion welding. In this investigation an attempt has been made to improve the welded joint strength through using of electron beam welding (EBW). Due to special features of EBW, e.g. high energy density and accurately controllable beam size and location, in many cases it has proven to be an efficient method for joining difficult to weld materials. In this paper, the effects of EBW parameters on the ultimate tensile strength (UTS) has been investigated, The experiments were based on one-variable-at-a-time (OVAT) method,
Materials Letters, 2020
The effect of electron beam welding process on the microstructural and mechanical characteristics of newly developed 3rd generation AW2099 heat treatable aluminium lithium (Al-Li) alloy was investigated. Non-dendritic equi-axed zone (EQZ) is formed at the heat affected zone (HAZ) – weld metal (WM) interface. This zone consists of fine equi-axed grains, while the eutectics based on α-aluminium + θ-Al2Cu are preferentially precipitated at the grain boundaries (GB). Increased content of iron, silicon and manganese was detected in some inter-dendrite sites. Furthermore, β-AlLi and γ-Al2Li3 compounds were recorded in the columnar dendritic zone (CDZ). Electron beam welding (EBW) resulted in dissolution of strengthening precipitates, thus the decrease in nano-indentation hardness in EQZ was observed in comparison to HAZ.
Journal of Materials Engineering and Performance, 2023
The variations of microstructure and mechanical properties of the joints with different welding heat input were investigated. As the heat input increased, excessive melting of TA15 alloy facilitated the formation of Ti-Cu compounds at the TA15 interface, increasing the brittleness of the TA15 interface. Moreover, high heat input also caused the HAZ softening by grain coarsening and deteriorated the performance of the joint. However, low heat input was adverse to the complete melting of Cu66V34 alloy and induced the formation of welding pores. It also weakened the strength of the joint. Under optimum welding parameters, (Ti,V) solid solution formed at the titanium interface, replacing Ti-Cu intermetallic compounds (IMCs). Therefore, the joint of sample 2 presented the highest strength (378MPa) and fractured along the HAZ of QCr0.8 alloy due to the HAZ softening resulting from grain coarsening.
Effect of Electron Beam Welding on Microstructure and Mechanical Properties of Ti-6Al-4V Alloy
Several trials were conducted to join two 7 mm thick, mill annealed Ti-6Al-4V alloy plates, by electron beam welding (EBW). Different values of the processing parameters, such as, accelerating voltage, beam current and welding speed, were selected with the objective of obtaining full depth penetration in the weld. The weldments were characterized for their mechanical properties, microstructure and phase composition. While the microstructure of the base metal consisted of slightly elongated α phase and transformed β phase, the microstructure of the fusion zone consisted of dispersed acicular martensite α' phase. The microstructure of the HAZ consisted of two distinct regions, viz., fine grain and coarse grain zone regions. The results indicated that microhardness in the fusion zone was higher than that in the base metal. The UTS and YS of the weld metal were higher than that of the weld joint and base metal. However, the % elongation is lower due to the formation of the acicular martensite α' phase in the weld metal.
Electron beam welding (EBW) technique was used to perform dissimilar joining of plain carbon steel to Fe-7%Al alloy under three different weld conditions such as with beam oscillation, without beam oscillation and at higher welding speed. The effect of weld parameters on the microstructure and mechanical properties of dissimilar joints was studied using optical microscopy, SEM, EBSD, hardness, tensile and erichsen cup tests. Microstructure results show that the application of beam oscillation resulted in uniform and homogeneous microstructure compared to without beam oscillations and higher welding speed. Further, it was observed that weld microstructure changes from equiaxed to columnar grains depending on the weld speed. High weld speed results in columnar grain structure in the weld joint. Erichsen cup test results show that the application of beam oscillation results in excellent formability as compared to high weld speed. Tensile test results show no significant difference in strength properties in all three weld conditions, but the ductility was found to be highest for joints obtained with the application of weld beam oscillation as compared to without beam oscillation and high weld speed. This study shows that the application of beam oscillations plays an important role in improving the weld quality and performance of EBW dissimilar steel to Fe-Al joints.
Welding of Ti6Al4V and Al6082-T6 Alloys by a Scanning Electron Beam
Metals
This work presents the results of an investigation into the influence of beam offset on the structure and mechanical properties of electron-beam-welded joints between Ti6Al4V and Al6082-T6 alloys. The experimental procedure involved the use of specific technological conditions: an accelerating voltage of 60 kV, an electron beam current of 35 mA, a specimen motion speed of 10 mm/s, and a beam offset of 0.5 mm towards both alloys, as well as welding without an offset. The phase composition of the joints was analyzed using X-ray diffraction (XRD). The microstructure and chemical composition of the seams were studied by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results obtained for the structure of the joints show that the beam offset has a significant influence on the structure. The microhardness was studied by means of the Vickers method. The results for the microstructure showed that the welding procedure without offset and with an offset ...
2006
The effect of processing parameters on mechanical and microstructural properties of aluminium alloy 6082-T6 Friction stir-welded (FSW) joints were investigated in the present study. Different welded specimens were produced by employing variable rotating speeds and welding speeds. Tensile strength of the produced joints was tested at room temperature and the correlation with process parameter was assessed. Microstructures of various zones of FSW welds are presented and analyzed by means of optical microscopy and microhardness measurements. Several studies have been conducted to investigate the properties and microstructural changes in Friction Stir Welds in the aluminium alloy 6082-T6 in function of varying process parameters. The experimental results indicated that the process parameters have a significant effect on weld macrostructure and mechanical properties of joints.
Vacuum, 2009
The use of different procedures for electron beam welding of 17 mm thick Ti-6Al-4V plate and the difficulties found in this process are analysed. When this alloy was welded autogeneously the presence of significant amounts of a martensite was observed, recommending looking for another solution. In the early trials a V joint design was used but distortions and defects were detected in the welds when multipass procedures were considered. Consequently, for the remaining weldments K or I joint configurations were selected. Initially, Ti-6Al-4V wire was preferred in order to match mechanical properties with base material but no significant improvement was found leading to consideration of using a less alloyed filler metal. Different commercially pure titanium filler metals have been employed to optimise the performance of the fusion zone of electron beam weldments. In a second paper [1] the influence of the welding procedure on the mechanical properties of the various joints will be discussed.
Materials Science Forum, 2000
Reduced Activation Ferritic-Martensitic steels (RAFM) are chosen as the candidate material for structural components in fusion reactors. Gas Tungsten Arc (GTA) welding is one of the candidate process for fabricating the structural components made of RAFM steel. A variant of GTA welding process called as Activated Tungsten Inert Gas (A-TIG) welding has been reported to overcome the limitations of GTA welding and enhance creep rupture life in F-M steels. In the present work, 10 mm thick RAFM steel is welded by conventional TIG and A-TIG welding processes and the effect of welding techniques on the microstructure and mechanical properties are compared. Post Weld Heat Treatment (PWHT) conditions are optimized in A-TIG weld joint to get improvement in impact toughness values. TEM investigation on weld metals revealed that the martensite lath and prior austenitic grain boundaries are decorated with M 23 C 6 precipitates and the lath size was in the range of 0.3-0.4 μm. Very fine MX precipitates are seen in intra martensite laths and very fine sub grain formation was observed after tempering treatment. Hardness and strength properties are higher for A-TIG weld joint while ductility is similar for both the weld joints. An impact toughness of 155 J was obtained in the A-TIG weld joint on full size sample.