Microstructure and Mechanical Behavior of Friction-Stir-Welded 2017A-T451 Aluminum Alloy (original) (raw)
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Archive of Mechanical Engineering, 2014
Friction stir welding is a solid state innovative joining technique, widely being used for joining aluminium alloys in aerospace, marine automotive and many other applications of commercial importance. The welding parameters and tool pin profile play a major role in deciding the weld quality. In this paper, an attempt has been made to understand the influences of welding speed and pin profile of the tool on friction stir welded joints of AA6082-T6 alloy. Three different tool pin profiles (tapered cylindrical four flutes, triangular and hexagonal) have been used to fabricate the joints at different welding speeds in the range of 30 to 74 mm/min. Microhardness (HV) and tensile tests performed at room temperature were used to evaluate the mechanical properties of the joints. In order to analyse the microstructural evolution of the material, the weld’s cross-sections were observed optically and SEM observations were made of the fracture surfaces. From this investigation it is found that...
Tensile properties and fracture locations of friction-stir-welded joints of 2017-T351 aluminum alloy
Friction stir welding (FSW) is a new and promising welding process that can produce low-cost and high-quality joints of heat-treatable aluminum alloys because it does not need consumable filler materials and can eliminate some welding defects such as crack and porosity. In order to demonstrate the friction stir weldability of the 2017-T351 aluminum alloy and determine optimum welding parameters, the relations between welding parameters and tensile properties of the joints have been studied in this paper. The experimental results showed that the tensile properties and fracture locations of the joints are significantly affected by the welding process parameters. When the optimum revolutionary pitch is 0.07 mm/rev corresponding to the rotation speed of 1500 rpm and the welding speed of 100 mm/min, the maximum ultimate strength of the joints is equivalent to 82% that of the base material. Though the voids-free joints are fractured near or at the interface between the weld nugget and the thermo-mechanically affected zone (TMAZ) on the advancing side, the fracture occurs at the weld center when the void defects exist in the joints.
Fatigue & Fracture of Engineering Materials & Structures, 2011
The effects of advancing speed and rotational speed on the microstructure and the mechanical properties of friction stir welded 7075-T6 aluminium alloy sheets were studied. The fatigue strength of sound joints was measured and compared to tensile testing results. Macrographs and microhardness maps were carried out to reveal the microstructure transformations. Fractographic observations were made to identify the failure mechanisms. The effects of welding parameters on the fatigue strength are discussed in terms of welding pitch k (mm/rev) and heat input (J/mm). At a high welding pitch, crack initiation at the root of the circular grooves left by the tool on the weld surface is the most detrimental failure mechanism. As the size and the depth of the grooves are related to the welding pitch, the fatigue strength increases when the welding pitch is reduced. However, when the heat input is excessive, the failure is caused by sub-surface defects produced after abnormal stirring and/or by softening of the heat-affected zone. Lateral lips on the weld surface edges also have an effect on the fatigue strength for intermediate welding pitch values.
Procedia Structural Integrity, 2019
The present study is attributed towards better tensile and impact properties of friction stir welded joints between AA6061-T6 and AA2014-T6 alloys with minimum or no void formation. Two different tool pin profiles, threaded with three intermittent flat faces (TIF) and truncated square pyramidal shaped (TPZ) tool pins were selected. Dissimilar joining was carried out using different combinations of tool rotation (660, 900, 1200 rpm) and welding speeds (36, 63, 98 mm/min). Results revealed that for TIF tool pin, the maximum joint tensile strength was achieved at tool rotational speed of 1200 rpm with welding speed of 98 mm/min. On contrary, the maximum impact energy was recorded for joints prepared with TPZ tool pin at 900 rpm tool rotation and 63 mm/min welding speed. Detailed metallurgical characterization of different weld zones and fractographic studies were also performed and discussed.
Materials Transactions, 2007
Dissimilar aluminum alloys such as 2024-T3 and 7075-T6 plates 3 mm thickness were friction stir butt welded. The welding was carried out at a constant welding speed of 100 mm/min and rotation speeds of 400, 800, 1200, 1600 and 2000 min -1 . Effects of rotation speeds and fixed location of two alloys on microstructures especially the homogeneity of elemental distribution in the stir zone (SZ), hardness distributions, and tensile properties of the joints were investigated. The homogeneity of constituents of the two alloys in the SZ was analyzed by a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscopy (EDS). At the lowest rotation speed of 400 min -1 there was no mixing of two alloys in the SZ and a border between them was observed regardless of the fixed location. Increase of rotation speed more than 400 min -1 brought about a mixed structure likewise onion ring with periodic change of equiaxed grain size and heterogeneous distribution of alloying ...
2013
Friction-stir welding (FSW), a solid-state innovative joining technique, is being widely used for joining aluminium alloys for the aerospace, marine, automotive industries and many other applications of commercial importance. FSW trials were carried out using a vertical machining centre (VMC) on an AA6061 alloy. The main objective of the present work was to evaluate the weld-processing parameters of FSW for the AA6061-T6 alloy and to determine the properties of the obtained joints with respect to the welding speed. The experiments were conducted by varying the welding speed between 55–70 mm/min and the rotating speed was fixed at 1700 r/min. The tensile properties, microstructure, microhardness, fractography and corrosion resistance of the FSW joints were investigated in this study. The result showed that there was a variation in the grain size in each weld zone depending upon the material and the process parameters of FSW in a joint. The coarsest grain size was observed in the heat...
Defect formation during dissimilar aluminium friction stir welded T-joints
Mechanics & Industry
AA8011 remains one of the largest used aluminium alloys due to excellent ductility, corrosion resistance and sufficient strength in H14 conditions. The 5754, due to high strength and corrosion resistance finds key applications in marine, process industry, automobile and nuclear applications. A T-joint combination of the two alloys (when stronger forming is stiffeners) results in significant weight savings. The T-joint between 8011 and 5754 (with the latter forming the stringer) is highly prone to defect formation due to the stronger material being placed away from the heat source. In this paper, friction stir welding of AA5754 and AA8011 aluminium alloys in T-lap configuration is performed. Effects of processing parameters namely tool transverse speed, rotational speed and shoulder diameter on the weld properties are studied with the help of micro-hardness, macrostructure and microstructure analysis. Analysis of defects such as tunnel and kissing bond, and mechanism of defect format...
Al-Nahrain Journal for Engineering Sciences, 2017
Friction stir spot welding (FSSW) is a modern solid-state joining process able to weld similar and dissimilar overlap joints in different classes of materials and is widely being considered for automotive industry. In this work, the mechanical behavior ) i.e. tensile shear tests, Microhardness(, and microstructure of friction stir spot welded joints were studied for AA6061-T6 aluminum alloy sheets with thickness of 1.6 mm. Series of FSSW experiments were conducted using vertical CNC milling machine type "C-tek". FSSW is carried out at different pin profiles (cylindrical, taper, and triangular) and tool rotational typically speeds, i.e. 800, 1000, 1200 and 1400 rpm. Based on the welding experiments conducted in this study, the results show that sheets welded by triangular pin tool have highest tensile shear load, of 3.2 kN, followed by welds with cylindrical pin, while welds made using taper pin has the tensile shear load 2.1 kN at optimum speed of 1200 rpm. Also the pin sh...
Advances in Materials Science and Engineering, 2013
2A12-T4 aluminum alloy was friction stir spot welded, and the microstructural characteristics and mechanical properties of the joints were investigated. A softened microstructural region existed in the joint, and it consisted of stir zone (SZ), thermal mechanically affected zone (TMAZ), and heat affected zone (HAZ). The minimum hardness was located in TMAZ, and the average hardness value in SZ can be improved by appropriately increasing welding heat input. The area of complete bonding region at the interface increased with increasing welding heat input because more interface metals were mixed. In a certain range of FSSW parameters, the tensile shear failure load of the joint increased with increasing rotation speed, but it decreased with increasing plunge rate or decreasing shoulder plunging depth. Two kinds of failure modes, that is, shear fracture mode and tensile-shear mixed fracture mode, can be observed in the tensile shear tests, and the joint that failed in the tensile-shear ...