Grain Structure, Crystallographic Texture, and Hardening Behavior of Dissimilar Friction Stir Welded AA5083-O and AA5754-H14 (original) (raw)
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Key Engineering Materials, 2021
The welding between two different grades of aluminum alloy, specifically AA5083 and AA6061-T6, is very difficult to obtain optimal results when using conventional welding methods such as TIG/MIG welding. Therefore, a solid-state joining technique is highly recommended to overcome these problems, one of which is friction stir welding (FSW). The effect of rotation speed on microstructure, microhardness, and tensile properties of dissimilar Friction Stir welded AA5083 and AA6061-T6 aluminum alloys were investigated. Three different rotation speeds (910, 1500, and 2280 rpm) were used to weld the dissimilar alloys. The metallographic analysis of joints showed the presence of various zones such as BM (base material), HAZ (heat affected zone), TMAZ (thermo-mechanically affected zone), and NZ (nugget zone) were observed and analyzed by mean of optical and scanning electron microscope. The results showed that increasing the rotation speed from 900 to 2280 rpm made grain coarsening in NZ and ...
Nugget Formation and Mechanical Behaviour of Friction Stir Welds of Three Dissimilar Aluminum Alloys
Materials
The aim of this research was to investigate the influence of the properties of the base materials and welding speed on the morphology and mechanical behavior of the friction stir welds of three dissimilar aluminum alloys in a T-joint configuration. The base materials were the AA2017-T4, AA5083-H111, and AA6082-T6 alloys in 3 mm-thick sheets. The AA6082-T6 alloy was the stringer, and the other alloys were located either on the advancing or retreating sides of the skin. All the T-joint welds were produced with a constant tool rotation speed but with different welding speeds. The microstructures of the welds were analyzed using optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and the electron backscatter diffraction technique. The mechanical properties were assessed according to micro-hardness, tensile, and fatigue testing. Good quality welds of the three dissimilar aluminum alloys could be achieved with friction stir welding, but a high ratio betwe...
Characterisation of Friction Stir Welded (FSW) AA5083-H111
IASSA 2012 Book of Abstracts Aerospace Technology: in Africa and the World 17 & 18 September 2012 Centurion, South Africa, 2012
Friction Stir Welding (FSW) has become the most important evolving welding technology for the proposed integral aluminium structures for aerospace fuselage to avoid high cost, excessive weight. The fatigue performances of FSW parts are superior to riveting. FSW entails a nonconsumable rotating cylindrical tool, consisting of a shoulder and pin, being pushed in to induce heat to plasticise the material and then traversed along the abutting surfaces of the two plates to be welded. Several factors influence the resulting microstructure and mechanical characteristics, and tool transverse and rotational speed are the most significant. Characterization of selected pioneering FSW components is presented. AA5083-H111 was selected because of its superplasticity, formability, weldability, high strength and corrosion resistance. It has been the preferred material for manufacturing of pressure vessels for aircrafts and spaceships, and vehicle bodies’ structures. A CNC milling machine was converted to weld 3mm thick plates of 360mm by 120mm at combinations of different rotational (400, 500 and 630rpm) and welding speeds (50, 60 and 70mm/min) using a tapered probe and cylindrical shoulder at zero tilt angle. Tensile testing and bend testing were undertaken. The macrostructure and fractured surfaces were observed using an optical microscope and an SEM in secondary electron mode. Stress-strain relationships of the welds were different. Compared to the base material, FSW samples had lower strain-to-failure results, owing to strain localization in the weld. H1, welded at 400rpm and 50mm/s had the highest UTS, 99.3±0.2%, whereas H2, welded at 400rpm and 70mm/s had the highest yield strength, 97.7±0.3%. Welds performed at 400 rpm were generally flaw-free, while higher weld speeds produced welds with tunnels, due to the low forging pressure. In the macrostructure, the weld nugget could be easily distinguished from the TMAZ (Thermo- Mechanically Affected Zone) on the advancing side, because the grains were finer, being recrystallized and equiaxed. However, no distinct boundary existed on the retreating side. The joint-line remnant, which comprises amorphous clusters of alumina, was observed in the nugget, but had no effect on mechanical properties. There was an increase in hardness in the weld zone, towards the retreating side, due to grain refinement and better weld consolidation. Conversely, there was a decrease in hardness in the TMAZ. The weld nugget average hardness of all flaw-free samples was 79.8±4.6HV0.1, with no definite relationship between weld parameters and hardness profiles. Tensile specimens fractured in the TMAZ on the advancing side at 45° to the far-field stress, because of reduced micro-hardness, strain localization and as well as the presence of tunnels in the flawed samples. Generally, failure occurred in a brittle mode, but areas of local ductile shear and quasi-cleavage fracture were observed in the SEM. This research demonstrated that good weld efficiency was obtainable on FSW of AA5083-H111 with a CNC milling machine of sufficient welding power.
Journal of Materials Science, 2012
Dissimilar friction stir welds of aluminum alloys AA5086 in annealed and AA6061 in T6 temper conditions were investigated in terms of residual stress, grain structure and precipitation distribution in different zones of the welded joints. Optical metallography and transmission electron microscopy were used to characterize microstructures of different zones of the welds. In addition, residual stress profile and local mechanical properties of different zones were evaluated employing X-ray diffraction method and digital image correlation technique. It was found that softening in the AA6061-T6 side occurs in regions with weld peak temperature higher than 300°C. The micro-hardness profile results and TEM investigations also showed that thermo-mechanical affected zone of AA6061 side with large plate-shaped b precipitates is the softest region of the joints in AA6061 side. Furthermore, residual stress distribution within the samples is not directly dependent on the local mechanical properties of different zones of the joints.
Materials & Design, 2009
In present work friction stir welds produced in 1 mm thick plates of AA 6016-T4 aluminium alloy, with two different tools, were analysed and compared concerning the microstructure and mechanical properties. For each tool, the welding parameters were optimized in order to achieve non-defective welds. Assuming a relation between the welding parameters and the energy input per unit of length of the weld [Seidel TU, Reynolds AP. Visualization of the material flow in AA2195 friction stir welds using a marker insert technique. Metall Mater Trans A 2001;32A:2879-84; Sato YS, Urata M, Kokawa H. Parameters controlling microstructure and hardness during friction stir welding of precipitation-hardenable aluminum alloy 6063. Metall Mater Trans A 2002;33(3):625-35; Lim S, Kim S, Lee CG, Kim S-J. Tensile behavior of friction-stri-welded Al 6061-T651. Metall Mater Trans A 2004;35(9):2829-35; Yang B, Yan J, Sutton MA, Reynolds AP. Banded microstructure in AA2024-T351 and AA2524-T351 aluminum friction stir welds: Part I. Metallurgical studies. Mater Sci Eng A 2004;364(1-2):55-65; Peel MJ, Steuwer A, Withers PJ, Dickerson T, Shi Q, Shercliff H. Dissimilar friction stir welds in AA5083-AA6082. Part I: process parameter effects on thermal history and weld properties. Metall Mater Trans A 2006;37:2183-193; Gerlich A, Su P, Yamamoto M, North TH. Effect of welding parameters on the strain rate and microstructure of friction stir spot welded 2024 aluminum alloy. J Mater Sci 2007;42(14):5589-601; Lombard H, Hattingh DG, Steuwer A, James MN. Optimising FSW process parameters to minimise defects and maximise fatigue life in 5083-H321 aluminum alloy. Eng Fract Mech 2008;75(3-4):341-54]
Influence of tool rotation and welding speed on the friction stir welding of AA 1100 and AA 6061-T6
AIP Conference Proceedings, 2018
Dissimilar welding of aluminum is an innovation used to increase the effectiveness and efficiency in making a product or component. It has been applied on the automotive industry, aerospace, and shipbuilding. Aluminum has low weldability in compared with steel material because of the oxide layer on the surface of aluminum. The welding problems of aluminum can be overcome by using a solid state welding such as friction stir welding (FSW). The objective of this study was to determine the strength of the welding joint and the microstructure of dissimilar welding joint with different series of aluminum. The tensile testing was performed with the weld directions of 0° and 45° to assess the formability, hardness testing, and microstructure of FSW. In this study, welding process was conducted to combine aluminum 1100 series (low strength aluminum) and aluminum 6061-T6 series (high strength aluminum) in the 2 mm thickness of aluminum sheet. The analysis was done by making comparison of the strength between dissimilar and similar aluminum series. The results showed that the dissimilar weld types, both in angle orientation of 0° and of 45° had fracture location on the HAZ area of 1100 aluminum series. The highest results of tensile strength were 78.07 MPa and 75.26 MPa for weld angle orientation of 0° and 45°, respectively. Weld angle orientation had significant effect to the strain where value of the welding direction of 0° was 10.99% and of 45° was 13.8%. Hardness test in the weld zone generated diverse values because the material stirring was not homogenous, whereas the similar welding was more stable in the welding area. Microstructure investigation on the dissimilar aluminum welding found a hook defects in the weld nugget. In the HAZ area, the grain size of 6061-T6 increased while of 1100 material decreased. It might be affected by the temperature and the aluminum characteristic. Meanwhile, in weld nugget, the grain size increased due to the stirring tool joint and heating during the welding process.
Science and Technology of Welding and Joining, 2011
The aim of this investigation is to study the effect of geometric tool parameters on mechanical and microstructural behaviours during dissimilar friction stir welding of 5 mm thick plates of AA 5086-O and AA 6061-T6. Three tool geometries were used, including a tool with a concave shoulder and a conical probe with three grooves, flat shoulder and threadless cylindrical probe, and a tool with a flat shoulder and a threaded cylindrical probe. It was found that the tool with a concave shoulder and a conical probe with three grooves produces higher heat input and temperatures that provides more homogeneous stir zones than the other tools. In addition, the grain sizes of the stir zone in the AA 6061 side of all the welds are finer than those produced in the AA 5086 side, and decreasing the weld pitch, i.e. a ratio of welding to rotational speed, results in coarser grain structures in the stir zone.
Metals
Friction stir welding of aluminum alloys has been progressively used in different industries on the ground of higher welding quality in comparison to fusion welding. In this article, friction stir welding of 6061-T6 aluminum alloy with 9.6 mm thickness was carried out by using three different welding speeds (63, 89 and 110 mm/min). The effect of welding speed on macro-and microstructure, micro hardness, tensile properties and kissing bond was investigated. Results show that the Low Hardness Zone was moved toward the weld center by increasing the welding speed. The average micro hardness in the weld nugget zone increased from 60.1 to 67.6 HV with the raise of welding speed from 63 to 110 mm/min. Thermo Mechanical Affected Zone was clearly revealed using Electron backscatter diffraction (EBSD). The kissing bond was studied by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) mapping. It was proven that the damaging effect of kissing bond was linked to location of this discontinuity, although the growth of kissing bond was linked to higher welding speed. The maximum value of Ultimate Tensile Strength (UTS) (159 MPa) was obtained at 110 mm/min, whereas the Yield Strength (YS) in the sample at 89 and 110 mm/min welding speed exhibit the same trend with 137 MPa and 134 MPa respectively.
Acta Materialia, 2003
Welding seam (WS) of a 2205DSS/Q235 laser-beam welded (LBW) joint consisted of a martensitic phase and a small amount of residual austenite. The microstructure of the heat-affected zone (HAZ) of the 2205DSS side was ferrite-dominated. The HAZ of the Q235 side consisted of a coarse-grained zone (near the WS) and a fine-grained zone which was a result of the thermal cycling. The WS had the was highest hardness, and the hardness value of the HAZ was slightly higher than that of the respective base metal. The strength of these welding joints was approximately 460 MPa. The residual stress was investigated using a finite element method, hole-drilling method, and X-ray diffraction analysis. The results revealed two high stress regions on either side of the WS. The residual stress of the WS was relieved substantially because of the martensitic transformation at 400°C.