The aim of this work is to analyse the process of frictionstirwelding (FSW) of 3 mm thick aluminium plates made of high strength aluminiumalloy - 2024T3, as well as to assess the mechanical properties of the produced joints. FrictionStirWelding is a modern procedure which enables joining of similar and dissimilar materials in the solid state, by the combined action of heat and mechanical work. This paper presents an analysis of the experimental results obtained by testing the butt welded joints. Tensile strength of the produced joints is assessed, as well as the distribution of hardness, micro-and macrostructure through the joints (in the base material, nugget, heat affected zone and thermo-mechanically affected zone). Different combinations of the tool rotation speed and the welding speed are used, and the dependence of the properties of the joints on these parameters of welding technology is determined.
FrictionStirWelding (FSW) is a solid state welding process developed and patented by The Welding Institute (TWI) in 1991. It is emerged as a novel welding technique to be used in high strength alloys that were difficult to join with conventional welding techniques FrictionStirWelding (FSW) is a relatively new joining process that has exhibited many advantages over traditional arc welding processes, including greatly reducing distortion and eliminating solidification. The present work aims to determine the feasibility to weld two pieces of aluminum plate (100 x 50 x 6 mm) by frictionstirwelding process and study the effect on the mechanical properties of weldingjoints.
Welding is defined as a process of joining two or more materials at their respective contacting surfaces via the suitable application of heat and/or pressure (Groover, 2007). Aluminum welding is a crucial, mostly owing to its complexity and the presence of numerous defects at the joint, due to high chemical reactivity with oxygen, high thermal conductivity, and high hydrogen solubility at high temperature. All these factors can cause the presence of defects on the weld bead (Maggiolino and Schmid, 2008). Welding can be represented by three major methods; fusion welding, solid state welding, and adhesive bonding (Kalpakjian, 1997).
As the lightest materials among constructional alloys, Magnesium alloy are expected to be widely used in transportation and aerospace industries [1-3]. However, one of the main limitations for the application of magnesium alloy is its poor formability due to its intrinsic HCP crystal structure. To improve the ductility of magnesium alloys, there are extensive works on the development of fine grained magnesium alloys, which are produced through techniques such as spray forming, powder metallurgy, and severe plastic deformation techniques [4-5].FSWwhich was invented by the welding institute (TWI) of the UK in 1991  is a welding process in which a non-consumable welding tool is used to generate both the frictional heat and mechanical deformation simultaneously in order to make a solid state joint. Although FSW has been investigated extensively in the case of aluminum and magnesium alloys , but there are A few texture studies regarding FSW aluminum and magnesium alloys have been reported. Sato et al.[8, 9] have reported a detailed texture analysis of FSW welds. The study of the texture evolution is required to understand the anisotropic characteristics of welds and their influence on mechanical properties. In our work, we chose to work with the magnesium alloy AZ91. The main interest in magnesium alloys lies in the fact that they are the lightest metallic materials currently available (magnesium density is about 1.74 g/cm 3 ). The use of magnesium alloy as a structural material is beneficial in reducing the weight of a vehicle. Thus, magnesium alloys possess excellent specific properties and are being designed to replace steel and aluminum in many structural applications. In general, they have about the same corrosion resistance as mild steel in similar environments but are less corrosion resistant than aluminum alloys.  Moreover, magnesium alloys have limited strength
Frictionstirwelding is an emerging solid-state joining process which is used to join metals and alloys having low weld ability. The process has provided an improved way of satisfactorily joining aluminium alloys, especially the precipitation hardens able aluminium alloys like AA 7XXX series. The fusion welding of AA 7XXX series alloy is generally not preferred due to its highly sensitive to weld solidification cracking. FrictionStirWeldingparameters such as tool pin profile, rotational speed, welding speed, and axial force control the mechanical properties of the FS welded joints significantly. These works focused on the consequence of tool pin profile on the weldment tensile strength of the joints were calculated.
Extensive work on the influence of pin geometry on me- chanical properties of 2014 aluminiumalloyfrictionstir welds has been carried out by Zhao et al. . Taper screw thread pin weld was reported to have the highest weld joint efficiency (75%) compared to the threaded cylindrical tool pin profile welds. The tools have all along been designed predominantly by the trial-and-error approach . Most of the previous investigations on the design of tool geometry were focused on optimizing the tool pin profile with respect to microstructure and mechanical properties. However, the study did not provide any clear guidelines for the optimal design of tool geometry. While the effect of different pin profiles has been studied, very little effort has been made to study the influence of tool pin profile on the generation of heat during welding. Several studies concerning the calculation of thermal loading during FSW process are available in literature. Some of these studies [20,21] are based on the critical assumption that the heat generated due to pin-material interaction is very low compared to that generated by the shoulder and hence may be neglected. The influence of tool pin profiles on FSW was hardly dis- cussed in the published literature.
The feasibility of replacing the riveting process with frictionstirwelding (FSW) technology in the assembly of fuselage skin-stiﬀener panels was the objective of several scientiﬁc papers in the last decades [1–6]. The potential of FSW to result in signiﬁcantly lower assembly times and manufacturing costs, yet higher productivity, cannot be overemphasized. However, commercial applications of this process require addressing issues such as strength analysis and design as well as optimizing the manufacturing process parameters for more reliable welds with minimum distor- tion [7, 8]. One of the many experimental strategies used to determine the process parameters as well as to optimize the process is deﬁned “by trial” and relies on the researcher’s technical and theoretical process knowledge . This strategy consists of a sequential procedure wherein the value of just one parameter among the set of parameters identiﬁed in the previous experiment is varied. This speciﬁc parameter is the one that mostly inﬂuences the process response while keeping ﬁxed the level of the other parameters . Such an approach has at least two disadvantages: it lacks objectivity in determining mathematical relations between process inputs and response variables and it also lacks eﬃciency and
In FSW process heat generated by friction between the surface of the plates and the contact surface of a special tool, composed of two main parts: shoulder and pin. Shoulder is responsible for the generation of heat and for containing the plasticized material in the weld zone, while pin mixes the material of the components to be welded, thus creating a joint. This allows for producing defect-free welds characterized by good mechanical and corrosion properties. The advantages of FSW are due to the fact that the process is carried out with the material to be welded in the solid state. Avoiding melting prevents the production of defects, due, for instance, to the presence of oxygen in the melting bath, and limits the negative effects of material metallurgical transformations and changes strictly connected with changes of phase. Finally, the reduced thermal flux, with respect to traditional fusion welding operations, results in a reduction in residual stress state in the joints and, consequently, in distortions in the final products .
The tensile properties and fracture locations of the welded joints are dependent on rotational speed of the tool and other process parameters like rotational speed, welding speed and axial force of the tool, tool tilt angle etc. The lower rotational speed results lower heat input and defects like crack and pinholes in frictionstir processed zone and resulted lower tensile values. On the other hand when the rotational speed increases (1400 rpm and 1500 rpm), the heat input also increases which results poor tensile properties due to rise in temperature, which increases grain growth, higher rotational speed also effects in the metallurgical change like re- precipitation, solubilisation and coarsening of strengthening precipitates at the weld zone area and lowering of dislocation density .
The present study documents various efforts for improving the mechanical properties of frictionstir welded joints of AA2198/AA2024 in both T8 and T3 heat treatment conditions. Five different pin profiles (tapered cylindrical, straight cylindrical, thread cylinder, cone and square) with three different shoulder profiles (flat, spiral, and fan) were investigated on simple AA2024 in order to determine the defect-free joints conditions with these tools. They were characterized by means of visual inspection, microstructure analysis, microhardness, and tensile tests. The tools which are able to produce bead on plate weld for AA2024, were selected for joining AA2024 and AA2198. Besides, the influences of traverse and rotational speeds and T8 post weld heat treatment (with and without pre-straining) on the joint mechanical properties have been assessed for the optimal tool. Furthermore, the effect of active cooling during welding to avoid high temperatures has been investigated by FEM simulation. The following points are the main conclusions of the study:
knowledge of the joining mechanism, and the metallurgical and mechanical transformations it induces in the base materials. Actually the effectiveness of the obtained joint is strongly dependent on several operating parameters. First of all, the geometric parameters of the tool, such as the height and the shape of the pin and the shoulder surface of the head, have a great influence on both the metal flow and the heat generation due to friction forces. Secondly, both the rotating speed and the feed rate have to be selected in order to improve “nugget integrity” that results in a proper microstructure and eventually in good strength, fatigue resistance and ductility of the joint. In FSW process heat generated by friction between the surface of the plates and the contact surface of a special tool, composed of two main parts: shoulder and pin. Shoulder is responsible for the generation of heat and for containing the plasticized material in the weld zone, while pin mixes the material of the components to be welded, thus creating a joint. This allows for producing defect-free welds characterized by good mechanical and corrosion properties. The advantages of FSW are due to the fact that the process is carried out with the material to be welded in the solid state. Avoiding melting prevents the production of defects, due, for instance, to the presence of oxygen in the melting bath, and limits the negative effects of material metallurgical transformations and changes strictly connected with changes of phase. Finally, the reduced thermal flux, with respect to traditional fusion welding operations, results in a reduction in residual stress state in the joints and, consequently, in distortions in the final products .
mand for lightweight equipment, these alloys have been increasingly used. In many applica- tions, superior properties of both aluminium alloys and titanium alloys, such as high strength, low weight and low cost are needed. Because of many differences between these two metals, such as differences in crystal lattice, melting temperature, thermal conductivity, and coeffi- cient of linear expansion, it is very difficult to achieve a defect-free joint between these two alloys [3-4]. The 7075 aluminiumalloy, in which zinc is the main alloying element, is a pre- cipitation hardened alloy. It is one of the strongest aluminium alloys which is used in many spatial structures and places that require high strength-to-weight ratio [5-6]. Titanium and its alloys have high specific strength and good corrosion resistance and because of these two de- sirable properties, they have been widely used in the aerospace industry. Nowadays, due to the increasing application of titanium alloys, the joining of aluminium alloys to titanium al- loys has to be considered carefully. The use of conventional fusion welding of titanium leads to the formation of brittleness, distortion and high residual stresses. Therefore, solid state join- ing processes are more appropriate to avoid problems caused by melting and freezing [7-8]. Frictionstirwelding is widely used for heat treatable and non-heat treatable aluminium alloys, such as 2xxx, 3xxx, 5xxx, and 7xxx series. Some attempts have been made to study frictionstirwelding on similar and dissimilar alloys, such as the alloy series AA 2024 / 5754 , 5086 , AA6061 [11-13], AA7075 [14-15], and AA6061 / 7075  , as well as on alu- minium die casting alloys and aluminium foams [17-22].
AluminiumAlloy AA7075 (Al–Zn–Mg–Cu) is one of the strongest aluminium alloys in industrial use today. Its high strength to weight ratio, together with its natural aging characteristics, makes it attractive for a number of aircraft structural applications . The alloy derives its strength from precipitation of Mg2Zn2 and Al2CuMg phases. A major problem with this alloy is that it is not fusion weldable. It is extremely sensitive to weld solidification cracking as well as heat-affected zone (HAZ) liquation cracking due to the presence of copper. Frictionstirwelding (FSW) is a solid state welding technique invented in 1991 by the welding institute (TWI). This process is effective for welding of various aluminium, magnesium and copper alloys . In FSW process a non- consumable rotating tool consisting of two parts, pin and shoulder, moves along the weld line. The joining is accomplished as a result of the localized frictional heat and plastic deformation associated with the movement of material from the front to the back of the rotating pin. It has been reported that the nature of the weldments materials as well as the FSW parameters such as tool rotational and traverse speeds, tool geometry, and joint design have a significant influence on the weld quality and consequently the determination of the optimum FSW conditions is very important [3-5]. Several investigations were carried out to study the effect of FSW parameters on the microstructural and mechanical characteristics of aluminium alloys. For instance, Shifting et al.  studied the effects of weldingparameters (pin rotation speed, welding speed and welding pressure) on the quality and mechanical properties of the 01420 Al–Li frictionstir welded joints. They found that the heat input for forming the defect free joints reduces with the increase of the welding speed or the decrease of the rotation speed. The heat input had little influence on the transverse tensile strength of the joints. Cavaliered et al.  studied the effect of weldingparameters on mechanical and microstructural properties of AA6056 joints produced by FSW at several tool rotating (500, 800 and 1000 r.p.m) and traverse (40, 56 and 80 mm/min) speeds. The results showed that the material ductility reaches the highest values for 40 and 56 mm/min welding traverse speed and the lowest rotating speed (500 r.p.m), decreasing strongly as increasing the rotating speed and the welding speed. Moreover, the highest tensile strength is reached in correspondence of the higher rotating speeds (800 and 1000 r.p.m) for the highest welding speed (80 mm/min).
In this experimental work, an extensive investigation had been carried out on Al Alloy (AA6061) grade aluminum alloy plates. This material is taken under investigation due its popularity in aircraft. The material of weld tool used High Carbon Steel. The tool material is used high carbon steel due to its low wear rate. Hence an attempt has been made to study the effect of influence of tool shape on the mechanical properties (tensile strength) of (AA6061) in single and double sided frictionstir welds in this project. In this work the speed of tool rotation were taken as 3080 rpm, transverse speed as 30mm/min. and tool tilt angle was taken as 2 0 . In both single and double pass, the highest tensile strength of the joints was obtained by using the square pin profile tool. The square pin profiles tool is best and tensile strength significantly decreases for, cylindrical, triangular and threaded pin profile tool due to defect formation. In double sided weld, the joints fabricated by cylindrical pin profiled tool showing almost matching tensile properties to that of square pin tool profile
Abstract: Aluminum alloy Al 2024-T3 were successfully joined using frictionstir spot jwelding joining (FSSW). Satisfactory joint strengths were obtained at different weldingparameters (tool rotational speed, tool plunge depth, dwell time) and tool pin profile (straight cylindrical, triangular and tapered cylindrical). Resulting joints were welded with welded zone. The different tools significantly influenced the evolution on the stir zone in the welds. Lap-shear tests were carried out to find the weld strength. Weld cross section appearance observations were also done. The macrostructure shows that the weldingparameters have a determinant effect on the weld strength (x: the nugget thickness, y: the thickness of the upper sheet and SZ: stir zone). The main fracture mode was pull out fracture modes in the tensile shear test of joints. The results of tensile shear tests showed that the tensile-shear load increased with increasing rotational speed in the shoulder penetration depth of 0.2 mm. Failure joints were obrerved in the weld high shoulder penetration depth and insufficient tool rotation.
The frictionstirwelding (FSW) process is a solid-state joining process and the joining temperature is lower than that used in the fusion welding processes. Therefore, for dissimilar metal welding, FSW is considered to oﬀer several advantages over fusion welding. The present work investigated the weldability of duralumin and titanium alloys using frictionstirwelding. The aluminum plates used in this work were 2024- T3 and 7075-T651, and the titanium plates used were pure titanium and Ti-6Al-4V. The average tensile strength of the Ti/2024 FSW joints was 311 MPa, and the tensile strength of the Ti/2024 joint was higher than that of the Ti/7075 FSW joint when the joining conditions were the same. A mixed region of Ti alloy and Al alloy was observed at the joint interface, and the joints mainly fractured at this region, where there was an intermetallic compound layer. In this region, a TiAl 3 intermetallic compound was detected by XRD. Therefore, it can be understood that this
process. In particular, it can be used to join high-strength aerospace aluminum and other metallic alloys that are hard to weld by conventional fusion welding. It was performed on 4mm thickness Al6061 and Al5083 dissimilar Aluminum alloys. Aluminum alloy light weight, softer, tendency to bend easily, cost effective in terms of energy requirements so aluminum alloy has selected in this FSW technique. In this welding when two metals are joined with the help of heat generated by rubbing metals against each other. The frictionstirwelding is mostly used for joining aluminum alloys. The main defects occurring in this welding are holes, material flow rate. These defects are mainly caused due to improper selection of weldingparameters. In this project the mechanical properties of FSW dissimilar aluminum alloy Al5083 and Al6061 has tested with the help of universal testing machine, hardness testing by Vickers hardness at various zones of the welded joints. In this experimental the testing of mechanical properties based on the input parameters such as rotational speed, welding speed and offset angle with proper weldingparameters. Finally, the experimental results will be compared with microstructures are analyzed by optical microscope.
C. Influence of process parameters on FSW of AL6063 In the study, R.Muthu Vaidyanathan, MahboobPatel, N.SivaRaman, D.Tedwors investigate about Optimum parameters to joining AA6063 butt joints. Rotatory speed, transverse speed, and axial force are the key factors considered for study. The material AA6063 was cut in size of 150x 100x 5 mm. The plates were positioned in a butt joint configuration of 100 mm long; the width is 150 mm and the FSW process is performed in a normal direction to the plates. They use rotational speeds 1000 rpm, 1500 rpm traverse speeds 0.5 mm/s and 1 mm/s axial loads 4000N, 6000N. A group of 4 samples were ready to determine the mechanical properties using an EDM wire cutting machine. Here, by using the Analysis of variance (ANOVA) they find out the factor is most effect the tensile strength and hardness. From the Analysis of Varience technique they concluded that welding speed was the key input parameter with the greatest statistical effect on mechanical properties such as tensile strength, deformation, and hardness. A max nominal Ultimate stress (101Mpa) shown by tool with optimal process parameters of tool rotatory speed, 1000 rpm; axial force, 6000N and transverse speed of 1mm / sec. Axial force and rotatory speeds are the powerful parameters for equivalent stress induced in the tool followed By velocity of rotation. It is found that for all samples the percentage of deformation is lower, showing that the amount of heat liberated in the process is lower.
A study was made of weldability of 4mm-thick Aluminiumalloy 5083 plates using frictionstirwelding. The plan of experiments was prepared based on abilities of universal milling machine. The weldingparameters in FrictionStirWelding (FSW) play a principle role in quality of the weld. The tool rotational speeds of 900r/min, 1120r/min, 1400r/min and 1800r/min, the welding speed of at 40mm/min were taken. The butt-joint types of aluminium plates were welded and then mechanical and thermal properties were to be analyzed. The microstructures of various regions were observed and analyzed by means of optical and scanning electron microscope. The tensile properties and micro-hardness were evaluated for the welded joint. The speeds are 900rpm, 1120 rpm, 1400rpm and 1800rpm. The temperatures taken for thermal analysis were also varying with the tool rotational speeds respectively. The effects of different tool pin profiles on the frictionstirwelding will also be considered for analysis. Different tool pin profiles are circular, tapered circular. As the joining process in frictionstirwelding is done below the melting point of base metal, it can be considered as the most significant development in metal joining world. It is essential to measure the amount of temperature distribution during frictionstirwelding as it had direct influence over the mechanical properties of the weld zone and heat affected zone. However, it is difficult to measure temperature in the weld zone due to the plastic deformation produced non- consumable rotating tool. In this research proposal, development in the analysis of heat generation and temperature distribution are addressed.
industries for various applications like bridge decks, ship panels, aerospace, and transportation components due to their light weight and low distortion . AA5086 is representative of non-heat-treatable 5xxx series of aluminium alloys having high formability and moderate strength. It has applications in marine, automotive, and aerospace industries in fabrication of light struc- tural components, where strength to weight ratio is a major concern and has to be as much as possible . Colligan investigated the relevance of FSW to oshore and marine industries and suggested it as a cost-diminishing and defect-free joining method as compared to conventional joining methods . Taban and Kaluc showed the superiority of FSW to the conventional joining methods in fabrication of AA5086 aluminiumalloyjoints . Inuence of rotational and welding speeds on microstructural and mechanical properties of AA5086 joints was studied by Aval and Loureiro and a sensible correlation between the studied parameters was found . Jamalian et al. suggested the appropriate combination of weldingparameters to get sound and defect-free AA 5086 aluminiumalloyjoints produced using FSW . Amini and Gharavi experimentally set up the proportional relation be- tween corrosion current density in heat aected zone and welding speed of tool in FSW of AA5086 alu- minium alloy . The microstructural and mechanical properties of AA5086 joints are dierent from those of the base material as explained by the numerous studies reported in the literature; on the other hand, corrosion behavior of the joints has received rare attention.