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Micro- and Macro- Mechanical Properties of Pinless Friction Stir Welded Joints in AA5754 Aluminium Thin Sheets

Authors:
Michela Simoncini at Università Politecnica delle Marche
Michela Simoncini
D. Ciccarelli at Università Politecnica delle Marche
D. Ciccarelli
Forcellese Archimede at Università Politecnica delle Marche
Forcellese Archimede
M. Pieralisi at Università Politecnica delle Marche
M. Pieralisi
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Abstract

The effect of process parameters, tool configuration and geometry on FSW of thin sheets in AA5754 aluminium alloy was widely investigated. Tools in “pin” and “pinless” configurations were used. It was shown that the “pinless” tool allows the obtaining of mechanical properties higher than those of the “pin” one. An investigation was also carried out in order to evaluate the microstructure of the joints. Welds obtained with the “pin” tool exhibit a more pronounced grain refinement than the one observed using the “pinless” one even though the presence of cavities and less homogeneity strongly affect the mechanical properties of joints.
Available via license: CC BY-NC-ND 3.0
Content may be subject to copyright.
Procedia CIRP 18 ( 2014 ) 9 – 14
Available online at www.sciencedirect.com
2212-8271 © 2014 Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/3.0/).
Peer-review under responsibility of the International Scientifi c Committee of the “International Conference on Manufacture
of Lightweight Components – ManuLight 2014”
doi: 10.1016/j.procir.2014.06.099
ScienceDirect
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© 2014 Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/3.0/).
Peer-review under responsibility of the International Scientifi
c Committee of the “International Conference on Manufacture
of Lightweight Components – ManuLight 2014”
10 M. Simoncini et al. / Procedia CIRP 18 ( 2014 ) 9 – 14
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... In particular, surface preparation does not need to be performed prior to welding, and protective gas and additional weld metal are not required. Moreover, the approach exhibits a high welding performance and can achieve smooth welding surfaces [8,9].The problems of cracking, distortion, porosity, and strength reduction, which occur when joining Al alloys through melt welding, can be eliminated by using the FSW method [10][11][12][13][14]. In addition to Al alloys, Mg alloys, Ti alloys, Cu, steel, bronze, brass, polymer, and composite materials can also be successfully joined using the FSW method [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. ...
... It was noted that the tool tilt angle considerably influenced the mechanical properties of the weld in the FSW process. The mechanical properties of the joints prepared using the tool at an angle during the FSW process were superior to those of the joints prepared at a tool angle of 0° [5,13,14]. The strength of Specimen 9 (900/80/1), corresponding to a high speed and large feed rate, was considerably lower because a homogeneous mixture could not be achieved owing to a lack of sufficient heat input. ...
Effect of double-sided friction stir welding on the mechanical and microstructural characteristics of AA5754 aluminium alloy
Article
  • Sep 2021
AA5754Al alloy is widely used in industry. However, as in the case of all Al alloys, the 5xxx series Al alloys cannot be easily joined through fusion welding techniques. To address this problem, in this study, the effect of double-sided friction stir welding at various tool rotational speeds (450, 710, and 900 rpm), feeding rates (40, 50, and 80 mm × min ⁻¹ ), and tool tilt angles (0°, 1°, 2°) on the welding parameters and mechanical and microstructural characteristics of AA5754 Al alloy was determined. Tensile strength tests and microhardness tests were performed to examine the mechanical properties of the welded specimens. The microstructures of the welded zone were examined by obtaining optical microscopy and scanning electron microscopy images. The tensile test results indicated that the specimens exhibited the highest welding performance of 95.17 % at a tool rotational speed, feed rate, and tool tilt angle of 450 rpm, 50 mm × min ⁻¹ and 1°, respectively.
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... μFSW using a pinless tool is substantially different in comparison to welding with a pin tool because, with the pinless tool, the material flow mechanism and its mixing entirely depend upon the features created on the shoulder surface [58]. Although by now, the study related to the dissimilar μFSW using a pinless tool has been carried out only by Simoncini and Forcellese [43], there are several works related to similar μFSW that positively demonstrates the use of a pinless tool [59,60]. ...
... Among the works that use the pinless tool which is in similar μFSW, Simoncini et al. [59] welded 1 mm thick AA5754-H111 using both "pinless" and "pin" tool configuration. They deduced that irrespective of the welding parameters and shoulder diameters, relatively higher strength and ductility of the joints were obtained by using a "pinless" tool configuration as a result of the homogeneous grain refinement obtained. ...
Challenges, process requisites/inputs, mechanics and weld performance of dissimilar micro-friction stir welding (dissimilar μFSW): A comprehensive review
Article
  • Aug 2021
  • J Manuf Process
Dissimilar micro-friction stir welding (dissimilar μFSW) can be a preferred choice for joining dissimilar materials having thickness ≤ 1000 μm. The technique's potential applications are in miniaturized components, where the inherent benefits of the process, such as low temperature, low distortion, and clean joining, are advantageous compared to fusion welding. However, the challenges associated with dissimilar μFSW hinder its full potential applications in the relevant industries. The challenges are particularly a combination of two different characteristics of the process (i) the complexities of simultaneously fulfilling the dissimilar materials' demands due to the vast differences in the two materials' mechanical and thermal properties and (ii) the problems due to reduced sheet thickness. In this regard, the present work is a comprehensive and timely review of the research works done on dissimilar μFSW targeted at easily acquainting the research community about the know-how and the state of the art of the process. The review is broadly divided into three crucial parts: the process inputs/requisites, process mechanics, and process performance. The details about the μFSW tool, process parameters, and relative sheet positioning are discussed under the heading process inputs/requisites. Concerning the process mechanics, the intermetallic compound formation, defect generation, and material mixing are discussed. The joints' resulting performance is shown by detailing the essential properties such as formability, residual stresses, fatigue, hardness, and tensile strength. Additionally, several future research directions are presented at the end of this critical review
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... Sample F2 exhibited an average tensile strength of 495.83 MPa. In contrast, the tensile strength attained through the TIG welded connection was comparatively diminished [65,66]. It can be clearly seen in Figure. ...
Mechanical and Corrosion Properties of Friction Stir Welded and Tungsten Inert Gas Welded Phosphor Bronze
Article
Full-text available
  • Dec 2023
This study investigated the mechanical and corrosion properties of Friction Stir Welded (FSW) and Tungsten Inert Gas (TIG) welded phosphor bronze (CuSn4) joints. Corrosion tests were conducted on the welded joints, and the percentage of weight loss due to corrosion was measured at different time intervals. Results revealed that the percentage of weight loss due to corrosion of the TIG joint increased with time, whereas the percentage of weight loss due to corrosion of the FSW welded joint remained constant. This could be attributed to recrystallisation that happened in the solid-state welding, which reduced corrosion in the FSW welded joint. In addition, tensile tests were conducted to evaluate the strength of the joints. FSW with a spindle speed of 1300 rpm, weld speed of 0.06mm/sec, plunge depth of 0.25mm, pin profile of pentagon, and flat shoulder profile was found to produce good results. TIG welding with a welding speed of 1.75mm/sec, a gas flow rate of 7.5 cm ³ /min and an amperage of 120A also produced good results. The tensile strength of FSW was found to be approximately 1.6 times higher than that of TIG welding.
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... Many studies confirmed that pinless FSSW could be as good as or better than traditional spot welds in terms of mechanical performance [41,43,47]. It is important to note that the purpose of the rotating anvil in this type is to reduce the axial force reaction on the welding frame, which can improve the mechanical properties [46,[48][49][50]. ...
Friction Stir Spot Welding (FSSW) Scope and Challenges
Chapter
  • Nov 2023
At the end of the last century, Friction stir welding (FSW) technology was invented as a distinct solid-state welding technology. The rapid development in the research aspect has led to a steady increase in its industrial applications. Friction stir spot welding (FSSW) is a particular case of FSW with no transverse speed during welding. The success of the FSSW technique is determined by the welding parameters such as axial load, dwell time, rotational speed, and plunge depth, besides the tool’s material and geometry. Recently, several studies tried to modify the conventional FSSW, such as refill, swing and swept, besides the pin-less techniques. Expanding the applications of FSSW depends mainly on finding a clear understanding of this technique, such as finding the optimal values for the tool design and the welding parameters in addition to the heat generated and the behavior of the metal flow affected by the resulting microstructure and mechanical properties. The joint welding efficiency and performance discreteness are the major challenges for the FSSW application. This chapter describes the FSSW fundamentals, advantages, and classification. It discusses the effects of input welding parameters on the quality of the resulting weld joint, whether in similar or dissimilar metals. Furthermore, this chapter focuses on the research trials to overcome the industrial application limitations.
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... One such microjoining process is microfriction stir welding (MFSW), which was developed in the welding institute by Wayne Tomas. It is an eco-friendly and solidstate welding process [1]. Solid-state welding is a process of joining two metals or alloys by producing friction between the tool and the base materials. ...
Microfriction Stir Welding of Aluminium Using ABB IRB 1410 Robot
Article
Full-text available
  • May 2023
Industry 4.0 industries are relying on automation processes using robots. Robots are multifunctional reprogrammable machines tuned to be used in any process with high accuracy and repeatability. The advent of intelligent technology allows better precision in the welding process. One such robotic welding process is the robot microfriction welding process which is slowly replacing conventional ones. Robot microfriction stir welding (RMFSW) process mainly relays on friction between the tool and material making it more suitable for joining metals in the industries such as automotive and aerospace applications. The robot-assisted MFSW process can provide better joints without human intervention. In this work, a shrinking flange has been designed and fabricated to grip the end effector with the robot. A microfriction stir welding tool was manufactured using EN24 and used to weld 1 mm thin aluminium 1100 sheets. Both the flange and MFSW tools were designed in SOLIDWORKS software. Taguchi L9 was designed with three factors such as motor speed, traverse speed, and plunging depth. The robot microfriction stirs welded samples had controlled bead width and depth of penetration. Mechanical results show an improvement in hardness after the welding process. TOPSIS optimization technique was carried out. The motor speed of 20,000 rpm, traverse speed of 2 mm/sec, and plunge depth of 0.7 mm were found to be the best-optimized parameters.
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... The Welding Institute (TWI, UK) invented FSW in 1991. In its early stages, FSW was intended for welding aluminum alloys [30][31][32][33][34][35][36][37]. Nonetheless, FSW proved its effectiveness in joining a wide variety of metals such as steel [38][39][40][41][42][43], magnesium [44][45][46][47][48], and titanium [49][50][51][52]. ...
A Comprehensive Technical Review of the Friction Stir Welding of Metal-to-Polymer Hybrid Structures
Article
Full-text available
  • Dec 2022
Metal–polymer hybrid structures are becoming desirable due to their wide range of applications in the automotive, aerospace, biomedical and construction industries. Properties such as a light weight, high specific strength, and design flexibility along with the low manufacturing costs of metal–polymer hybrid structures make them widely attractive in several applications. One of the main challenges that hinders the widespread utilization of metal–polymer hybrid structures is the challenging dissimilar joining of metals to polymers. Friction stir welding (FSW) shows a promising potential in overcoming most of the issues and limitations faced in the conventional joining methods of such structures. Several works in the literature have explored the FSW of different metal-to-polymer combinations. In some of the works, the joints are examined based on processing parameter optimization, microstructural characteristics, and mechanical performances. It is, therefore, important to summarize the findings of these works as a means of providing a reference to researchers to facilitate further research on the utilization of FSW in joining metals to polymers. Thus, this work aims to present a comprehensive technical review on the FSW technique for joining metals to polymers by reviewing the reported literature findings on the impact of materials, tools, process parameters, and defects on the strength and microstructure of the produced joints. In addition, this work reviews and presents the latest practices aiming to enhance the metal–polymer joint quality that have been reported in the literature.
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... Metals represent the widest used materials in the manufacturing industries as structural applications are concerned. They are typically transformed by exploiting deformation [1][2][3], material removal and, finally, metal assembly processes [4,5]. These methods, even though are highly established in the manufacturing industries, present some limitations, especially regarding the possibility of realizing very complex shapes. ...
Environmental impacts assessment of Bound Metal Deposition 3D printing process for stainless steel
Article
Full-text available
  • Jan 2022
3D Printing consists in the manufacturing of three-dimensional products by depositing material, usually layer by layer. Since material is added only where needed, these techniques have the potential to minimize waste production, leading to a reduction of cost, energy consumption and environmental impacts with respect to traditional production processes. Bound Metal Deposition (BMD) is a 3D printing extrusion-based process for metals in which the components are build through the deposition of a metal powder held together a polymer binder. After the printing phase, the binder is removed by means of a solvent and then the part is sintered in a furnace. In this study, the environmental impacts and the mechanical properties of 17-4 PH stainless steel 3D printed parts are evaluated by means of the Life Cycle Assessment methodology and tensile tests. Moreover, two different scenarios were considered to evaluate the effects of a heat treatment process on the mechanical properties and the environmental sustainability of 3D printed parts. Results show that the heat-treated components represent the best alternatives when high mechanical properties are required but, on the other hand, they present high environmental impacts.
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Experimental and numerical assessment of thermomechanical and morphological characteristics of pin and pinless micro friction stir welds
Article
  • Nov 2023
In the realm of micro-Friction Stir Welding (FSW), distinct challenges arise compared to conventional FSW, encompassing faster heat dissipation through the backing surface, and higher impact of hooks on joint performance due to the reduced effective sheet thickness. Given the limited variability in tool design in micro-FSW, this study delves into the influence of pinless tool in comparison to pin tool on hook formation, temperature evolution, and bonding mechanisms. By conducting a combination of experiments and numerical investigations on 0.5 mm lap FSW joints, the study unveils that pin tool, with an 11% higher peak temperature and 46% greater effective sheet thickness, achieved 4% increase in joint strength with 26% lesser axial force during traversing. Pin tool exhibited a 10–11% higher proportion of recrystallized grains, with 11.1% and 57.6% grain refinement in the weld centre and hook regions, respectively, primarily due to pin-assisted material stirring. In contrast, pinless tool exhibited a flat nugget with directional grain growth toward the weld bottom. The pin weld demonstrated nearly three times the maximum equivalent plastic strain compared to the pinless weld, confirming the intense movement of plasticized material in the vicinity of the pin and effective intermixing across the sheet-interface.
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New methodology of dynamical material response of dissimilar FSWed Al alloy joint under high strain rate laser shock loading
Article
Full-text available
  • Aug 2022
  • Mater Des
This paper presents an innovative methodology of material characterization under high strain rate (order of 107s-1) laser shock loading coupled with microstructural and mechanical material features. To that scope, experimental and simulation analyses have been conducted for Al alloys (AA7075-T6 and AA2017-T4) and dissimilar Friction Stir Welded (FSWed) AA7075-AA2017 joint, under shock pressure of 4.5 GPa (laser power density of 3.5 GW/cm2). In order to perform proper in-depth material model simulation of these alloys and dissimilar pairs, Johnson-Cook (J-C) material model has been coupled with Grüneisen equation of state using the non-linear explicit code LS-DYNA. For the first time, we provided a way to differentiate between material behaviour in the cross-section and the in-plane rolling and welding direction. What is more, we have provided the link between microstructural features and mechanical properties such as microhardness, residual stresses and the identified material parameters. By achieving this goal, the bigger difference between studied planes was confirmed for strain hardening modulus, strain hardening exponent and strain rate sensitivity parameters. Obtained results and proposed methodology indicate high potential to predict material properties and behaviour of dynamically stressed parts and at the same time can be used for optimization of LSP process.
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Heat Input and Temperature Distribution in Friction Stir Welding
Article
Full-text available
  • Oct 1998
  • J Mater Process Manuf Sci
In this paper the heat input and temperature distribution during friction stir welding is investigated. The temperatures at different positions in the specimen thickness direction and perpendicular to the pin tool travel direction were recorded during welding under various welding conditions. It was found that the highest temperature in the welding seam is less that 0.8T(m). For the conditions used in this work, the temperature does not change appreciably in the specimen thickness direction. The temperature distribution perpendicular to the weld is nearly isothermal under the pin tool shoulder. Furthermore, increasing welding pressure and pin tool rotational speed increases the peak welding temperature. Finally, it is shown that the shoulder of the pin tool plays a very important role in the welding process.
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The influence of the ratio of “rotational speed/traverse speed” (ω/v) on mechanical properties of AZ31 friction stir welds
Article
Full-text available
  • Dec 2006
  • INT J MACH TOOL MANU
The influence of different parameters such as welding pressure, rotational speed, and traverse speed on the weld properties has been evaluated earlier but there are some important parameters yet to be thoroughly investigated. In this study, an effort has been made to determine the influence of different ratios of rotational speed/traverse speed on mechanical properties of different zones of friction stir welded AZ31 magnesium alloy. Mechanical properties of different zones were determined by a shear punch test. It was found out that increasing the aforementioned ratio leads to a slight decrease in yield and ultimate strength of the stir zone and the transitional zone. It was also observed that increasing rotational/traverse speed ratio increases the weld nugget size and decreases the incomplete root penetration.
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Mechanical properties and microstructure of joints in AZ31 thin sheets obtained by friction stir welding using "pin" and "pinless" tool configurations
Article
  • Feb 2012
  • MATER DESIGN
The effect of process parameters, tool geometry and size on friction stir welding of thin sheets in AZ31 magnesium alloy was widely investigated. In particular, two properly designed tools, with different values of the shoulder diameter, were used; each of them was manufactured both in the "pin" and "pinless" tool configurations. It was shown that at the lowest shoulder diameter investigated (8 mm), the pin tool configuration leads to the obtaining of ultimate tensile strength and ductility values higher than those provided by the "pinless" one. By increasing the shoulder diameter (19 mm), a strong beneficial effect on both ductility and strength of the joint is obtained even though the welding performed using the "pin" tool configuration is critically affected by the process parameters. An investigation has been also carried out in order to evaluate the micro-hardness and microstructure covering all regions of the welded joints. A different metal flow can be clearly observed depending on the presence/absence of pin. Finally, a more homogeneous microstructure is obtained using the "pinless" tool configuration.
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Friction Stir Welding of Al Alloy Thin Plate by Rotational Tool without Pin
Article
  • Dec 2011
  • J MATER SCI TECHNOL
For friction stir welding (FSW), a new idea is put forward in this paper to weld the thin plate of AI alloy by using the rotational tool without pin. The experiments of FSW are carried out by using the tools with inner-concave-flute shoulder, concentric-circles -flute shoulder and three-spiral-flute shoulder, respectively. The experimental results show that the grain size in weld nugget zone attained by the tool with three-spiral-flute shoulder is nearly the same while the grain sizes decrease with the decrease of welding velocity. The displacement of material flow in the heat-mechanical affected zone by the tool with three-spiral-flute shoulder is much larger than that by the tool with inner-concave-flute shoulder or concentric-circles-flute shoulder. The above-mentioned results are verified by numerical simulation. For the tool with three-spiral-flute shoulder, the tensile strength of FSW joint increases with the decrease of welding velocity while the value of tensile strength attained by the welding velocity of 20 mm/min and the rotation speed of 1800 r/min is about 398 MPa, which is 80% more than that of parent mental tensile strength. Those verify that the tool with three-spiral-flute shoulder can be used to join the thin plate of AI alloy.
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Precipitation microstructures in an AA6056 aluminium alloy after friction stir welding: Characterisation and modelling
Article
  • Nov 2008
  • MAT SCI ENG A-STRUCT
The effect of friction stir welding on the microstructure and local properties of the AA6056 alloy has been investigated for both T4 and T78 initial states. A particular attention was devoted to the relationship between the fine hardening precipitation within the affected zones and local hardness. In the heat-affected zones of the T4 weld an extensive heterogeneous precipitation is occurring on dislocations and dispersoids whereas the heat-affected zones of the T78 weld are characterised by the coarsening and dissolution of initial hardening precipitates and by heterogeneous precipitation on dispersoids. Modelling tools dedicated to the weld behaviour understanding have been developed: a physically based model for precipitation and hardening has been coupled to a model for thermal cycles. This model describes correctly both the microstructural evolution through the FSW joint and its consequence on hardness variations.
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Effect of the welding parameters and tool configuration on micro- and macro-mechanical properties of similar and dissimilar FSWed joints in AA5754 and AZ31 thin sheets
Article
  • Apr 2012
  • MATER DESIGN
The effect of welding parameters and tool configuration on the surface appearance, mechanical and microstructural properties of similar and dissimilar FSWed joints in AA5754 and AZ31 thin sheets was widely investigated. Two different tool configurations, with and without the pin, were used. As far as the similar friction stir welded joints in AZ31 and in AA5754 alloys are concerned, it was shown that the “pinless” tool leads to the obtaining of higher values of the tensile strength and ductility as compared to the “pin” one. On the contrary, by considering the dissimilar friction stir welding between AZ31 and AA5754 thin sheets, the welding process becomes very critical as the “pinless” tool is used. Sound dissimilar joints were obtained using the “pin” tool configuration, even though the effect of the material position with respect to the welding tool is a very important factor to be considered. A marked improvement in the surface appearance and mechanical properties was obtained by placing aluminium alloy in the advancing side and magnesium alloy in the retreating one. An investigation has been also carried out in order to evaluate the microstructural properties of similar and dissimilar welded joints.
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Influence of friction stir welding parameters on the microstructural and mechanical properties of AA 6016-T4 thin welds
Article
  • Oct 2008
  • MATER DESIGN
a b s t r a c t 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 proper-ties. 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 con-trolling 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], the welds produced were classified as ''hot" and ''cold welds". The results obtained showed that the ''hot" welds, obtained with the maximum tool rotational speed and the minimum traverse speed, have improved mechanical properties relative to the ''cold" welds that were in undermatch condition relative to the base material. The differences in mechanical properties between the two types of welds are explained based in TEM microstructural anal-ysis. Despite the undermatched characteristics of the ''cold" welds relative to the base material, formabil-ity tests demonstrated that these welds improve the drawing performance of the welded sheets.
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Influence of friction stir welding parameters on grain size and formability in 5083 aluminum alloy
Article
  • May 2007
  • MAT SCI ENG A-STRUCT
Friction stir welding (FSW) has received a great deal of attention as a new solid-state welding technique. In the present study, the relationship between the microstructure of stir zone and the mechanical property of FS-welded 5083 aluminum alloy was investigated. The microstructures of the stir zones consisted of fine equiaxed grains at various FSW conditions in FS-welded 5083 Al alloy. However, the grain size of the stir zone decreased with the decrease in friction heat flow during FSW. The ductility in FS-welded 5083 Al alloy increased with the decrease in friction heat flow. It was indicated that the formability in FS-welded 5083 Al alloy was improved by the refinement of grain size of the stir zone.
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Friction Stir Welding and Processing II
Article
  • Sep 2005
  • MAT SCI ENG R
Friction stir welding (FSW) is a relatively new solid-state joining process. This joining technique is energy efficient, environment friendly, and versatile. In particular, it can be used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding. FSW is considered to be the most significant development in metal joining in a decade. Recently, friction stir processing (FSP) was developed for microstructural modification of metallic materials. In this review article, the current state of understanding and development of the FSW and FSP are addressed. Particular emphasis has been given to: (a) mechanisms responsible for the formation of welds and microstructural refinement, and (b) effects of FSW/FSP parameters on resultant microstructure and final mechanical properties. While the bulk of the information is related to aluminum alloys, important results are now available for other metals and alloys. At this stage, the technology diffusion has significantly outpaced the fundamental understanding of microstructural evolution and microstructure–property relationships. # 2005 Elsevier B.V. All rights reserved.
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On the thermo-mechanical loads and the resultant residual stresses in friction stir processing operations
Article
  • Dec 2008
  • CIRP ANN-MANUF TECHN
In friction stir welding and processing both a thermal flux and a mechanical action are exerted on the material determining metallurgical evolutions, changes in the mechanical behaviour and a complex residual stress state. In the paper, the metallurgical changes are examined through numerical simulation and experiments to highlight and distinguish the effects of thermal and mechanical loadings. A particular focus is made on the residual stresses generated during the stir processing of AA7075-T6 aluminium blanks. The predictions of FE model are validated by experimental measurements. Lastly, this paper presents an in-process quenching of the processed blanks for improved mechanical properties and microstructure.
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