Analysis of dissimilar friction stir welding process for tensile properties of EN AW 2024 and EN AW 5083

The objective of the present study is to analyze the effect of dissimilar friction stir welding process parameters associated with the tool pin profile. Nine different welding experiments were conducted on EN AW 2024 and EN AW 5083 plates. Each of the welded joints was exposed to metallurgical and mechanical tests to determine the effect of the parameters on the welded joint's strength and characteristics. The welding responses or characteristics were analyzed using the statistical tools, grey relational analysis and analysis of variance. Thus, the contribution of each parameter to the process response (ultimate tensile strength and percentage of elongation) was analyzed, and an optimal welding condition was determined. The results of metallurgical analyses showed that the defective joints were mostly in the welded joints fabricated with a conical threaded pin, and the shape of the stir zone was affected by the pin profile and tool rotational speed. The metallurgical results were consistent with the tensile test results. Statistical analyses showed that the most effective parameter on the welded joint strength and elongation is tool rotational speed with 70.3 %. While the tool pin profile affects the stir zone shape, the strength and elongation are not affected. The effect of welding speed (5.6 %) is not significant on strength and elongation.     

Friction stir welding of dissimilar aluminum alloys AA2219 to AA5083 – Optimization of process parameters using Taguchi technique

The joining of dissimilar Al–Cu alloy AA2219-T87 and Al–Mg alloy AA5083-H321 plates was carried out using friction stir welding (FSW) technique and the process parameters were optimized using Taguchi L₁₆ orthogonal design of experiments. The rotational speed, transverse speed, tool geometry and ratio between tool shoulder diameter and pin diameter were the parameters taken into consideration. The optimum process parameters were determined with reference to tensile strength of the joint. The predicted optimal value of tensile strength was confirmed by conducting the confirmation run using optimum parameters. This study shows that defect free, high efficiency welded joints can be produced using a wide range of process parameters and recommends parameters for producing best joint tensile properties. Analysis of variance showed that the ratio between tool shoulder diameter and pin diameter is the most dominant factor in deciding the joint soundness while pin geometry and welding speed also played significant roles. Microstructural studies revealed that the material placed on the advancing side dominates the nugget region. Hardness studies revealed that the lowest hardness in the weldment occurred in the heat-affected zone on alloy of 5083 side, where tensile failures were observed to take place.     

Identification of the pin offset effect on the friction stir welding (FSW) via Taguchi – Grey relational analysis: A Case study for AA 7075 – AA 6013 alloys

The aim of this work is to present a case study relating to the dissimilar friction stir welding (FSW) ability of AA 7075‐T651 and AA 6013‐T6 by applying pin offset technique. An orthogonal array L18 was conducted to perform the overlapped weld seams using three different values of pin offset, welding speed and tool rotational speed along with two different pin profiles determine the impact of welding parameters on the tensile properties of friction stir welded joints. The nugget zone for each of overlapped weld seams exhibited a complex structure and also, the pin offset and profile also were found to have a great impact on the microstructural evolution of the nugget zone. The ultimate tensile strength, elongation at the rapture and bending strength of welded joints were measured in the ranges of 194–215 MPa, 1.79–3.34 % and 203–352 MPa. From the Taguchi based Grey relational analysis, the optimum welding condition was determined for the welded joint performed using a single fluted pin profile with the zero pin offset, tool rotational speed of 630 min^?1 and welding speed of 63 mm/min. Microstructural and macro‐structural observations revealed that welded joints exhibiting lower tensile strength are consistent of various types of defects (e. g. cracks, tunnels and cavities). The fracture location of welded joints was found to be on the heat affected zone and between the heat affected zone and AA 6013‐base metal. The tool and pin wear was not observed during the welding applications     

Establishing relationship between the base metal properties and friction stir welding process parameters of cast aluminium alloys

In friction stir welding (FSW), the material under the rotating action of non-consumable tool has to be stirred properly to get defect free welds in turn it will improve the strength of the welded joints. The welding conditions and parameters are differing based on the mechanical properties of base materials such as tensile strength, ductility and hardness which control the plastic deformation during friction stir welding. The FSW process parameters such as tool rotation speed, welding speed and axial force, etc. play a major role in deciding the weld quality. FSW Joints of cast aluminium alloys A319, A356, and A413 were made by varying the FSW process parameters and the optimum values were obtained. In this investigation, empirical relationships are established and they can be effectively used to predict the optimum FSW process parameters to fabricate defect free joints with high tensile strength from the known base metal properties of cast aluminium alloys.     

Predicting tensile strength,hardness and corrosion rate of friction stir welded AA6061-T6 aluminium alloy joints

AA6061-T₆ aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio and good corrosion resistance. The friction stir welding (FSW) process and tool parameters play major role in deciding the joint characteristics. In this research, the tensile strength and hardness along with the corrosion rate of friction-stir-butt welded joints of AA6061-T₆ aluminium alloy were investigated. The relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder diameter, pin diameter and tool hardness) and the responses (tensile strength, hardness and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified and reported here.     

Effect of tool rotational speed and pin profile on microstructure and tensile strength of dissimilar friction stir welded AA5083-H111 and AA6351-T6 aluminum alloys

The relatively new welding process friction stir welding (FSW) was applied in this research work to join 6 mm thick dissimilar aluminum alloys AA5083-H111 and AA6351-T6. The effect of tool rotational speed and pin profile on the microstructure and tensile strength of the joints were studied. Dissimilar joints were made using three different tool rotational speeds of 600 rpm, 950 rpm and 1300 rpm and five different tool pin profiles of straight square (SS), straight hexagon (SH), straight octagon (SO), tapered square (TS), and tapered octagon (TO). Three different regions namely unmixed region, mechanically mixed region and mixed flow region were observed in the weld zone. The tool rotational speed and pin profile considerably influenced the microstructure and tensile strength of the joints. The joint which was fabricated using tool rotational speed of 950 rpm and straight square pin profile yielded highest tensile strength of 273 MPa. The two process parameters affected the joint strength due to variations in material flow behavior, loss of cold work in the HAZ of AA5083 side, dissolution and over aging of precipitates of AA6351 side and formation of macroscopic defects in the weld zone.     

Effect of friction stir welding on the microstructure and mechanical properties of AA 6063-T6 aluminum alloy

In this study, AA 6063-T6 alloy plates were joined via friction stir welding using three different pin geometries (i. e., helical threaded, pentagonal and triangular) under various process parameters of tool rotational speed and welding speed. The microstructures and mechanical properties of the various welded joints were investigated. Macro-structural observations revealed that kissing bonds occurred in the welded joints due to fractured oxide layers. X-ray diffraction analysis indicated that the stir zones of the welded joints exhibited phases of Al₈Fe₂Si, Al₅FeSi, and Mg₂Si. In the welded joints, processed using a helical threaded pin, no tunnel-type defect was detected to occur; specimens were fractured outside of the joint region during tensile tests, indicating that the kissing bonds formed in the stir zones did not cause any deterioration in tensile strength or ductility. The welded joints processed using a helical threaded, pentagonal and triangular pin at 500 min⁻¹ tool rotational speed and 80 mm min⁻¹ welding speed exhibited a ductile deformation behavior along with a tensile strength in the range of 153 MPa to 155 MPa.     

Eccentric-weave FSW between Cu and AA 6061-T6 with reinforced Graphene nanoparticles

This study deals with the retrofication of micro- and macrostructural defects in joining aluminum and copper alloy using eccentric weave friction stir welding. In addition, graphene nanoparticles were added to strengthen the weldments. Welding experiments were conducted with two types of stir tool as (normal and offset pin) in linear and eccentric weave pattern. Results from this study reveal the possibility of tool tribology on eccentric stirring with tool pin offset producing a very minimal wear of 5?µm in comparison to other patterns of weld; defects on microscopic and macroscopic view of the weldments prove the existence of fragmental cracks in eccentric welding, and mechanical properties viz. yield strength of 187?MPa, ultimate tensile strength of 217?MPa, and elongation of 10% were found for the eccentric weave welded joints. This reveals the achievement of robust welded joints in the aluminum and copper alloys by eccentric weave welding with pin offset.     

Mikrostrukturelle,mechanische und korrosive Eigenschaften reibrührgeschweißter Stumpfnähte in Aluminiumlegierungen

Microstructural, mechanical and corrosive properties of friction stir welded aluminium joints Friction stir welding (FSW) is a novel solid state welding process. It allows joining of high strength aluminum alloys, generally considered as difficult-to-weld with conventional technologies, without loss in joint strength. Results of investigations on selfmade FSW butt joints of the aluminum alloys 2024-T3 and 6013-T4 are presented. First, the microstructure of the weld seam and heat affected zone is characterised metallographically and by hardness measurements. By tensile, fatigue endurance (SN) and fatigue crack propagation tests it is demonstrated, that especially the FSW-joints of 2024–T3 sustain high mechanical loadings. Investigations on the corrosion properties reveal a certain sensitivity of the 2024-T3 joints to intergranular and exfoliation corrosion.     

Influence of friction stir welding process and tool parameters on strength properties of AA7075-T6 aluminium alloy joints

The aircraft aluminium alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an alternative improved way of satisfactorily producing aluminium joints, in a faster and reliable manner. In this present work, the influence of process and tool parameters on tensile strength properties of AA7075-T₆ joints produced by friction stir welding was analysed. Square butt joints were fabricated by varying process parameters and tool parameters. Strength properties of the joints were evaluated and correlated with the microstructure, microhardness of weld nugget. From this investigation it is found that the joint fabricated at a tool rotational speed of 1400 rpm, welding speed of 60 mm/min, axial force of 8 kN, using the tool with 15 mm shoulder diameter, 5 mm pin diameter, 45 HRc tool hardness yielded higher strength properties compared to other joints.     

Warm and room temperature deformation of friction stir welded thin aluminium sheets

Friction stir welding is a welding solid state process of large potential advantages for aerospace and automotive industries dealing with light alloys. The metal to be welded is not melted and this avoids welding defects such as cracks and porosity. Moreover, there is no significant deterioration in mechanical properties due to phase transformations in the joint and low-cost and high-quality joints can be produced even from heat-treatable aluminium alloys, notably difficult to weld. In this study, very thin rolled sheets (0.8 mm in thickness) of 2024T3 and 6082T6 were friction stir welded, parallel to the rolling directions, obtaining similar joints (2024T3–2024T3 and 6082T6–6082T6) and dissimilar joints (6082T6–2024T3). Tensile tests at temperatures and strain rates of 170–230 °C and 10⁻³–10⁻⁵ s⁻¹ respectively were performed on the thin joints. The flow stress decreased with increasing temperature and decreasing strain rate. The ductility was quite independent from temperature and strain rate. The tensile stress–strain curves of the thin dissimilar joints placed at an intermediate level between the high strength 2024T3–2024T3 and low strength 6082T6–6082T6 flow curves. The fracture occurred in the middle of the stir zone for all the investigated joints and was of ductile type. Microhardness profiles were slightly modified by straining.     

Material flow and mechanical behaviour of dissimilar AA2024-T3 and AA7075-T6 aluminium alloys friction stir welds

The scope of this investigation is to evaluate the effect of joining parameters on the mechanical properties, microstructural features and material flow of dissimilar aluminium alloys (3 mm-thick AA2024-T3 and AA7075-T6 sheets) joints produced by friction stir welding. Mechanical performance has been investigated in terms of hardness and tensile testing. Material flow using the stop action technique has also been investigated in order to understand the main features of the mixing process. No onion ring formation has been observed; the boundary between both base materials at the stir zone is clearly delineated, i.e., no material mixing is observed. A non-stable rotational flow inside the threads has been identified due to the formation of a cavity on the rear of the pin. Microstructural observation has revealed the development of a recrystallised fine-grained stir zone, with two different grain sizes resulting from the two different base materials.     

Friction stir welding of dissimilar metal joints

Friction stir welding is a solid‐state welding technology, which is suitable for joining dissimilar metals such as aluminium and copper. Because the solidus temperature is typically not exceeded, the formation of intermetallic phases can be reduced when compared to fusion welding processes. In friction stir welding, the intermetallic layer thickness, which determines the seam properties, is influenced by the welding temperature and is formed in correspondence with the Arrhenius law. It is typically in the range of a few hundred nanometers thick. In turn, the process temperature is determined by the process parameters, primarily the rotational speed and the feed rate of the machine tool. In this study, a temperature‐controlled friction stir welding process has been applied to lap joints of aluminium and copper. Welding experiments with various welding speeds and probe lengths were performed in order to assess the effect of the temperature‐time profile near the welding interface. The joints were investigated by tensile shear tests as well as optical microscopy and scanning electron microscopy.     

5083铝合金搅拌摩擦焊接头的显微组织与力学性能

对8 mm厚5083-H321铝合金板进行了搅拌摩擦焊接试验,研究了焊接工艺参数对搅拌摩擦焊接头显微组织和力学性能的影响。结果表明:该搅拌摩擦焊接头焊核区显微组织为细小的等轴晶组织,热机影响区为拉伸弯曲变形组织,热影响区非常窄,其晶粒尺寸与母材相当;综合接头表面形貌和拉伸性能得到较佳的搅拌摩擦焊接工艺参数为使用搅拌针为三棱形带螺纹、轴肩为内扣型的搅拌头,主轴转速为300 r·min^-1,焊接速率为120 mm·min^-1;在该工艺条件下接头表面成形良好,抗拉强度可达到母材的94.5%。     

Effect of friction stir welding process parameters on the tensile strength of dissimilar aluminum alloy AA2024-T3 and AA7075-T6 joints

This work investigates the influence of friction stir welding parameters on the mechanical properties of the dissimilar joint between AA2024-T3 and AA7075-T6. Experiments are conducted consistent with the three-level face-centered composite design. Response surface methodology is used to develop the regression model for predicting the tensile strength of the joints. The analysis of variance technique is used to access the adequacy of the developed model. The model is used to study the effect of key operating process parameters namely, tool rotation speed, welding speed and shoulder diameter on the tensile strength of the joints. The results indicate that friction stir welding of aluminum alloys at a tool rotation speed of 1050 min⁻¹, welding speed of 40 mm/min and a shoulder diameter of 17.5 mm would produce defect less joint with high tensile strength.     

Fortschritte beim Rührreibschweißen von Aluminium,Magnesium und Stahl

Progresses on the friction stir welding of aluminium, magnesium and steel Friction Stir Welding (FSW) represents an innovative welding process for joining light metal, especially, aluminium and its alloys. Friction Stir Welding offers an attractive alternative to conventional fusion welding processes because of the excellent properties (particularly ductility), reproducibility, robustness, and surface finish obtained with the process. Within the scope of this work the Friction Stir Welding‐Process with its possible joint configurations is explained. The focus of this work concentrates on weldability studies concerning cladded aluminium alloys, aluminium cast alloys, aluminium tailored welded blanks both from similar and dissimilar joints produced in aluminium, magnesium and steel. The mechanical properties of the welded samples will be discussed.     

Microstructures and mechanical properties of friction stir welded dissimilar copper/brass joints

In this study, an experimental investigation has been carried out on microstructure and mechanical properties of friction stir welded copper/brass dissimilar joints. Effect of axial tool force to welding quality has been investigated under obtained optimal tool rotation rate and tool traverse speed conditions. The tool for the dissimilar copper/brass friction stir welding manufactured from X155CrMoV12–1 cold work tool steel with material number of 1.2379. The friction stir welding quality was investigated by welding surface inspections, microstructural studies, micro hardness measurements and tensile tests. The experimental studies have shown that constant axial tool force during pre‐heating and during welding process are very important. As a result, by using 2.5–3 kN of axial tool force during pre‐heating and 5.5 kN of axial tool force during welding process, copper/brass dissimilar joints with well appearance and higher mechanical strength can be obtained.     

Effect of pin offset on the mechanical properties of friction stir welded AA 6013 aluminum alloy plates

In this study, AA 6013 aluminum plates were butt‐welded with friction stir welding via pin offset technique. Macrostructural observations revealed that kissing bonds, originated from the broken oxide layers, were found to occur in the welded joints. The fracture location of welded joints after tensile tests was found to be outside the joint area, revealing that kissing bonds which were formed in the stir zone exhibited no detrimental effect on the mechanical properties of joints. Microstructural observations revealed that phases belonging to Mg₂Si, Al₄Cu₂Mg₈Si₇ and Al(MnFe)Si were observed in the x‐ray diffraction pattern of friction stir welded joints. The highest tensile strength with a value of 206 MPa was achieved with the process parameters of 1.5 mm pin offset towards the advancing side and 500 min^?1 tool rotational speed, leading the ratio of tensile strength of joint to ultimate tensile strength of base metal, also known as joint efficiency, to reach 74 %.     

Effects of Tilt Angle on the Properties of Dissimilar Friction Stir Welding Copper to Aluminum

In the present investigation, dissimilar materials such as electrolytic tough pitch copper, and aluminum 6061-T651 were welded by friction stir welding technology. Effects of tool tilt angle on the mechanical and metallurgical properties were studied experimentally for dissimilar material systems. In the present study, the tool tilt angle was varied from 0° to 4° with an interval of 1°, while the other parameters such as rotational speed, welding speed, tool pin offset, and workpiece material position were kept constant. Macrostructure analysis, tensile test, macro hardness measurement, scanning electron microscopy, and energy dispersive x-ray spectrographic tests were performed to evaluate the weld properties of dissimilar copper–aluminum joints. The results revealed that a defect free dissimilar copper–aluminum friction stir welding was achieved by tilt angles 2°, 3°, and 4°. The maximum tensile strength was reported to be 117 MPa and the macro hardness was reported to be 181 VH (in the nugget zone) at a tilt angle of 4°. The macro hardness was increased as the tilt angle increases from 0° to 4°. In addition to this, the thermo-mechanically affected zone (at the copper side) was found to be the weakest zone for a dissimilar copper–aluminum friction stir welding system.     

Artgleiche und artverschiedene reibrührgeschweißte Verbindungen aus AA2124+25 % SiC und AA2024

Similar and dissimilar friction stir welded joints made from AA2124+25 % SiC and AA2024 An aluminium matrix composite (AMC) consisting of an AA2124 matrix reinforced by 25 vol.% SiC particles was used to produce similar AMC+AMC and dissimilar AMC+2024‐T3 joints by friction stir welding. When the particle reinforced composite was located on the retreating side, material mixing was less intense for dissimilar joints. Nevertheless, a higher strength has been determined for this arrangement due to a hook‐like interlocking of both materials. Tensile test and S‐N fatigue behaviour is shown to be compromised by alignment of the reinforcement particles perpendicular to loading direction already in the particle reinforced base material. Welding residual stresses were determined through the cut‐compliance method in terms of stress intensities acting at the crack tip. The underlying residual stress distribution in the un‐cracked structure was calculated by the weight function method. Longitudinal tensile residual stresses were found to be higher in the monolithic material as compared to the particle reinforced composite. This held true both for similar and within dissimilar joints. Growth behaviour of cracks crossing the joint line was described and correlated with residual stresses for similar joints.