Plunge, traverse, and extract phases of a Friction Stir Weld done in 2219-T87 aluminum. Mississippi State University March, 2012. FRICTION STIR WELDING OF ALUMINIUM CONTENTS Introduction Properties, which makes Aluminium different Advantages of FSW Process (FSW) Applications Disadvantages. Schematic diagram of FSW process. Friction stir welding is therefore both a deformation and a thermal process, even though there is no bulk fusion. Friction stir welding and processing R.S. Mab aCenter for Friction Stir Processing, Department of Materials Science and Engineering, University of. Friction stir welding of aluminium alloys. P L Threadgill. 1, A J Leonard. H R Shercliff. 3 and P J Withers*4. TWI, Granta Park, Great Abington CB2. AL, UK2. BP International, Compass Point, 7. 1 Friction Stir and Friction Stir Spot Welding - Lean, Mean and Green Authors: C. Ruehl* *Friction Stir Link, Inc. Rotary Linear Stir MTI is a Full-Service Solutions Provider specializes in: FRICTION STIR WELDING Introduction Welding using friction as the major resource No filler material involved Welds created by, a) Frictional heating b) Mechanical. Friction Stir Welding at TWI Stephan Kallee and Dave Nicholas Introduction In late 1991 a very novel and potentially world beating welding method was conceived. Kingston Rd, Staines, Middx TW1. DY, UK3. Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1. PZ, UK4. School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7. HS, UK*Corresponding author, email philip. The comprehensive body of knowledge that has built up with respect to the friction stir welding (FSW) of aluminium alloys since the technique was invented in 1. The basic principles of FSW are described, including thermal history and metal flow, before discussing how process parameters affect the weld microstructure and the likelihood of entraining defects. After introducing the characteristic macroscopic features, the microstructural development and related distribution of hardness are reviewed in some detail for the two classes of wrought aluminium alloy (non- heat- treatable and heat- treatable). Finally, the range of mechanical properties that can be achieved is discussed, including consideration of residual stress, fracture, fatigue and corrosion. It is demonstrated that FSW of aluminium is becoming an increasingly mature technology with numerous commercial applications. In spite of this, much remains to be learned about the process and opportunities for further research and development are identified. Keywords: Friction stir welding, Aluminium alloys, Microstructure evolution, Plastic flow, Residual stress, Mechanical properties, Thermomechanically affected zone. Introduction. Historical background and principles. Radically new joining processes do not come along very often: friction stir welding (FSW) was one such event, being invented by the TWI in 1. By the end of 2. 00. TWI had issued 2. FSW. The principal features are shown in Fig. The side of the weld for which the rotating tool moves in the same direction as the traversing direction, is commonly known as the 'advancing side'; the other side, where tool rotation opposes the traversing direction, is known as the 'retreating side'. Frictional heat is generated, principally due to the high normal pressure and shearing action of the shoulder. Friction stir welding can be thought of as a process of constrained extrusion under the action of the tool. The frictional heating causes a softened zone of material to form around the probe. As the tool is traversed along the joint line, material is swept around the tool probe between the retreating side of the tool (where the local motion due to rotation opposes the forward motion) and the surrounding undeformed material. The extruded material is deposited to form a solid phase joint behind the tool. The process is by definition asymmetrical, as most of the deformed material is extruded past the retreating side of the tool. The process generates very high strains and strain rates, both of which are substantially higher than found in other solid state metalworking processes (extrusion, rolling, forging, etc.). Fig. 1. Schematic diagram of FSW process. Friction stir welding is therefore both a deformation and a thermal process, even though there is no bulk fusion. The maximum temperature reached is a matter of some debate. FRICTION STIR WELDING - researchgate.net PPT. Presentation Summary : INTRODUCTION. FRICTION STIR WELDING. FSW is a solid state joining process in which the material.Thermocouple measurements during FSW of aluminium alloys suggest that, in general, the temperature stays below 5. There is evidence of incipient melting for some aluminium alloys (e. The workpiece flow stress will fall rapidly as the solidus is approached, so that heating of the nugget at the tool/workpiece interface limits the available heat generation by reducing the torque. In addition considerable work has focused on using FSW to join dissimilar aluminium alloys. A summary of the AWS designations for wrought Al alloy groups and AWS basic temper designations applicable to heat- treatable Al alloys is contained within Table 1. Since FSW is a solid state process, it can be used to join all common aluminium alloys, including the 2xxx, 7xxx and 8xxx series which are normally challenging or impractical to weld by fusion processes. A key distinction is between non- heat- treatable and heat- treatable alloy series. In work hardened alloys (e. In age hardened alloys, the weld will normally be heated well above the dissolution temperature of the initial precipitates, enabling dissolution, reprecipitation and overaging to occur. Friction stir welded aluminium alloys can therefore contain microstructures covering the entire spectrum of normal tempers. Table 1 AWS designations for wrought Al alloy groups and basic temper designations applicable to heat- treatable Al alloys. The designation is followed by a time indicating the natural aging period, e. W 1 h. 5xxx. Magnesium: increases strength through solid solution strengthening and improves work hardening ability. TThermally aged: T1: cooled and naturally aged. T2: cooled, cold worked and naturally aged. T3: solution heat treated, cold worked and naturally aged. T4: solution heat treated and naturally aged. T5: cooled and artificially aged. T6: solution heat treated and artificially aged. T7: solution heat treated and overaged or stabilised. T8: solution heat treated, cold worked and artificially aged. T9: solution heat treated, artificially aged and cold worked. Magnesium- silicon. Recently there have been excellent general reviews of FSW covering a wide range of materials by Mishra and Ma. A recent ASM speciality handbook also covers FSW and friction stir processing. It is therefore considered timely to correct this omission. The present review draws on a wide selection of published data to summarise current understanding of the complex relationship between welding parameters, microstructure and properties for FSW of many aluminium alloys. Process modelling of FSW has evolved in parallel with empirical process development, and provides physical insight into all of these relationships. Since FSW modelling has been reviewed elsewhere. This leads to higher joint completion rates for FSW, even though the welding speeds may be lower. The latter depends very much on the specific equipment used, and comparisons are difficult. For example, the absence of a filler wire means that the process cannot easily be used for making fillet welds. Similarly, the fully mechanised nature of the process prevents its use for applications where access or complex weld shape is best suited to a manual process. The presence of a hole at the end of the weld from which the probe was withdrawn is often quoted as a disadvantage. In practice, this has seldom been a significant problem, as there are many possible solutions, which have been considered elsewhere. Although the process may reduce the strength of aluminium alloys, this can be compensated for if necessary by appropriate design of the joint, for example by locally increasing the thickness, but in most cases no changes are made. Process economics are generally considered favourable, but specific published data are lacking. However, it is known that the process drastically reduces weld preparation costs, skilled welder requirements and repair rates. Efficient power consumption is dependent on matching the size of machine being used to the size of weld being made, although this is not always a practical option. Fig. 2. Workpiece is held by two hydraulic clamps (one is obscured) between which welding head passes from right to left; head has just completed furthermost of three FSWs shown; b) typical welding head as it is removed from the plate; c) 2. Triflute MX tool - it is possible to use this tool with zero tilt angle; d) a 5. Triflat tool designed specifically for welding thicker sections. Applications. Commercial applications have been reported across many industries, and some selected examples are shown below which illustrate the widening appeal of the process. This list is representative rather than exhaustive, and it should be emphasised that new applications are appearing all the time. It should be noted that FSW does not restrict the operating temperature range of aluminium alloys, with applications ranging from cryogenic temperatures (e. Most FSWs used in production are butt welds, although lap welds and friction stir spot welds are also being applied with increasing frequency. Marine. It is believed that the first commercial application of FSW was the joining of 6xxx series alloy extrusions for use in fish freezing plants for fishing vessels. Friction stir welding has been used extensively in the aluminium superstructures of cruise ships such as the 'Seven Seas Navigator' which contain many kilometres of friction stir welds, mostly in 6xxx grade extrusions. The world's largest aluminium vessel, the Japanese fast ferry 'Ogasawara', launched in 2. FSW in its superstructure. The process has also been adopted for the large fuel tank for the Space Shuttle. The first aircraft to make extensive use of FSW in its airframe, the Eclipse 5. The needs of the automotive sector have driven the development of robotic FSW, to cope with the complex shapes and high volume/low cost culture of this market. These include tailoring microstructures for subsequent deep drawing and superplastic forming operations, and the ability to refine locally the microstructure of castings (for example, around stress concentrations, where a superior wrought microstructure would be preferable). Friction stir processing is not considered further in the present review. Friction stir welding process. Flow mechanisms and tool design. The metal flow and heat generation in the softened material around the tool are fundamental to the friction stir process. Material deformation generates and redistributes heat, producing the temperature field in the weld. But since the material flow stress is temperature and strain rate sensitive, the distribution of heat is itself governed by the deformation and temperature fields.
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