Tool Downscaling Effects on the Friction Stir Spot Welding Process and Properties of Current-Carrying Welded Aluminum–Copper Joints for E-Mobility Applications

According to the technical breakthrough towards E-Mobility, current-carrying dissimilar joints between aluminum and copper are gaining an increasing relevance for the automotive industry and thus, coming into focus of many research activities. The joining of dissimilar material in general is well known to be a challenging task. Furthermore, the current-carrying joining components in E-Drive consist of pure aluminum and copper materials with relatively thin sheet thickness, which are thermally and mechanically very sensitive, as well as highly heat and electrically conductive. This results in additional challenges for the joining process. Due to their properties, friction stir welding and especially fiction stir spot welding (FSSW) using pinless tools—i.e., as hybrid friction diffusion bonding process (HFDB) is more and more attractive for new application fields and particularly promising for aluminum–copper joining tasks in E-Mobility. However, the feasibility is restricted because of the relatively high process forces required during friction stir welding. Thus, to fulfill the high process and quality requirements in this above-mentioned application field, further research and process development towards process force reduction are necessary. This work deals with the application of the tool downscaling strategy as a mean of process force reduction in FSSW of thin aluminum and copper sheets for current-carrying applications in E-Mobility, where the components are very sensitive to high mechanical loads. The tool downscaling approach enables constant weld quality in similar process time of about 0.5 s despite reduced process forces and torques. By reducing the tool diameter from 10 mm to 6 mm, the process force could be reduced by 36% and the torque by over 50%. Furthermore, a similar heat propagation behavior in the component is observable. These results provide a good basis for the joining of E-Drive components with thermal and mechanical sensitive sheet materials using the pinless FSSW process.

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Microstructural and Mechanical Properties of Pure Aluminum, 5083 and 7075 Alloys Joined by Friction Stir Welding

Materials Testing ◽

10.3139/120.110323 ◽

2012 ◽

Vol 54 (4) ◽

pp. 240-245 ◽

Cited By ~ 2

Author(s):

Selim Sarper Yilmaz

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Pure Aluminum ◽

Friction Stir ◽

Aluminum 5083

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Shoulder Related Temperature Thresholds in FSSW of Aluminium Alloys

Materials ◽

10.3390/ma14164375 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4375

Author(s):

David G. Andrade ◽

Sree Sabari ◽

Carlos Leitão ◽

Dulce M. Rodrigues

Keyword(s):

Heat Generation ◽

Process Parameters ◽

Rotational Speed ◽

Aluminium Alloys ◽

Spot Welding ◽

Base Material ◽

Main Process ◽

Welding Temperature ◽

Friction Stir ◽

Tool Diameter

Friction Stir Spot Welding (FSSW) is assumed as an environment-friendly technique, suitable for the spot welding of several materials. Nevertheless, it is consensual that the temperature control during the process is not feasible, since the exact heat generation mechanisms are still unknown. In current work, the heat generation in FSSW of aluminium alloys, was assessed by producing bead-on-plate spot welds using pinless tools. Coated and uncoated tools, with varied diameters and rotational speeds, were tested. Heat treatable (AA2017, AA6082 and AA7075) and non-heat treatable (AA5083) aluminium alloys were welded to assess any possible influence of the base material properties on heat generation. A parametric analysis enabled to establish a relationship between the process parameters and the heat generation. It was found that for rotational speeds higher than 600 rpm, the main process parameter governing the heat generation is the tool diameter. For each tool diameter, a threshold in the welding temperature was identified, which is independent of the rotational speed and of the aluminium alloy being welded. It is demonstrated that, for aluminium alloys, the temperature in FSSW may be controlled using a suitable combination of rotational speed and tool dimensions. The temperature evolution with process parameters was modelled and the model predictions were found to fit satisfactorily the experimental results.

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Similar and dissimilar friction-stir welding of an PM aluminum-matrix hybrid nanocomposite and commercial pure aluminum: Microstructure and mechanical properties

Materials Science and Engineering A ◽

10.1016/j.msea.2016.04.078 ◽

2016 ◽

Vol 666 ◽

pp. 225-237 ◽

Cited By ~ 46

Author(s):

F. Khodabakhshi ◽

A. Simchi ◽

A.H. Kokabi ◽

A.P. Gerlich

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Pure Aluminum ◽

Aluminum Matrix ◽

Hybrid Nanocomposite ◽

Friction Stir ◽

Microstructure And Mechanical Properties ◽

Dissimilar Friction Stir Welding ◽

Commercial Pure Aluminum

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Stir zone material flow patterns during friction stir welding of heavy gauge AA5056 workpieces and stability of its mechanical properties

Metal Working and Material Science ◽

10.17212/1994-6309-2021-23.4-140-154 ◽

2021 ◽

Vol 23 (4) ◽

pp. 140-154

Author(s):

Tatiana Kalashnikova ◽

◽

Vladimir Beloborodov ◽

Kseniya Osipovich ◽

Andrey Vorontsov ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Friction Stir Welding ◽

Elevated Temperatures ◽

Thin Sheet ◽

Stir Zone ◽

Clear Correlation ◽

Material Structure ◽

Friction Stir ◽

Significant Difference

Introduction. Friction stir welding and processing are almost identical processes of severe plastic deformation at elevated temperatures. These technologies differ mainly in the purpose of its use: the formation of a hardened surface layer or producing a welded joint. However, it is known that both during welding and during processing of heavy gauge workpieces temperature gradients occur. As a result, the conditions of adhesive interaction, material plastic flow, and the formation of the stir zone change as compared to thin-sheet workpieces with fundamentally different heat dissipation rates. In this connection, the purpose of the work is to determine the regularities of the structure formation and stability of the mechanical properties in different directions in the material of 35-mm-thick aluminum-magnesium alloy samples produced by friction stir welding/processing. Research Methodology. The technique and modes of friction stir welding and processing of AA5056 alloy workpieces with a thickness of 35 mm are described. Data on the equipment used for mechanical tests and structural research are given. Results and discussion. The data obtained show the excess mechanical properties of the processing zone material over the base metal ones in all studied directions. Material structure heterogeneities after friction stir welding/processing of heavy gauge workpieces have no determining effect on the stir zone properties. At the same time, there is no clear correlation between the tensile strength values and the load application direction, nor is there any significant difference in mechanical properties depending on the location of the samples inside the stir zone. The average ultimate tensile strength values in the vertical, transverse, and longitudinal directions are 302, 295 and 303 MPa, respectively, with the yield strength values of 155, 153 and 152 MPa, and the relative elongation of 27.2, 27.5, 28.7 %.

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Axial Force Reduction in Friction Stir Welding of AA6061-T6 at Right Angle

Volume 2B: Advanced Manufacturing ◽

10.1115/imece2014-39649 ◽

2014 ◽

Cited By ~ 1

Author(s):

Yousef Imani ◽

Michel Guillot

Keyword(s):

Friction Stir Welding ◽

Solid State ◽

Axial Force ◽

Tool Design ◽

Industrial Robots ◽

Welding Parameters ◽

Minor Effect ◽

Friction Stir ◽

Force Reduction ◽

Solid State Joining

Invented in 1991, friction stir welding (FSW) is a new solid state joining technique. This process has many advantages over fusion welding techniques including absence of filler material, shielding gas, fumes and intensive light, solid state joining, better microstructure, better strength and fatigue life, and etc. The difficulty with FSW is in the high forces involved especially in axial direction which requires use of robust fixturing and very stiff FSW machines. Reduction of FSW force would simplify implementation of the process on less stiff CNC machines and industrial robots. In this paper axial welding force reduction is investigated by use of tool design and welding parameters in FSW of 3.07 mm thick AA6061-T6 sheets at right angle. Attempt is made to reduce the required axial force while having acceptable ultimate tensile strength (UTS). It is found that shoulder working diameter and shoulder angle are the most important parameters in the axial force determination yet pin angle has minor effect. According to the developed artificial neural network (ANN) model, proper selection of shoulder diameter and angle can lead to approximately 40% force reduction with acceptable UTS. Regions of tool design and welding parameters are found which result in reduced axial force along with acceptable UTS.

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Friction Stir Spot Welding: A Review on Joint Macro- and Microstructure, Property, and Process Modelling

Advances in Materials Science and Engineering ◽

10.1155/2014/697170 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 26

Author(s):

X. W. Yang ◽

T. Fu ◽

W. Y. Li

Keyword(s):

Mechanical Properties ◽

Friction Stir Welding ◽

Numerical Simulations ◽

Resistance Spot Welding ◽

Spot Welding ◽

Single Point ◽

Industrial Applications ◽

Friction Stir Spot Welding ◽

Microstructural Characteristics ◽

Friction Stir

Friction stir spot welding (FSSW) is a very useful variant of the conventional friction stir welding (FSW), which shows great potential to be a replacement of single-point joining processes like resistance spot welding and riveting. There have been many reports and some industrial applications about FSSW. Based on the open literatures, the process features and variants, macro- and microstructural characteristics, and mechanical properties of the resultant joints and numerical simulations of the FSSW process were summarized. In addition, some applications of FSSW in aerospace, aviation, and automobile industries were also reviewed. Finally, the current problems and issues that existed in FSSW were indicated.

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Analysis of tool wear and deformation in friction stir welding of unequal thickness dissimilar Al alloys

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420720971769 ◽

2020 ◽

pp. 146442072097176

Author(s):

Tanveer Majeed ◽

Yashwant Mehta ◽

Arshad Noor Siddiquee

Keyword(s):

Friction Stir Welding ◽

Tool Wear ◽

Tilt Angle ◽

Dissimilar Materials ◽

Welding Temperature ◽

Friction Stir ◽

Tool Shoulder ◽

Process Forces ◽

Wide Range ◽

Lower Tool

Friction stir welding between plates of unequal thickness, which are made from similar or dissimilar materials, finds wide range of applications in the aerospace and automotive sectors. Friction stir welding of plates made from dissimilar materials having unequal thicknesses is challenging. One of the major challenges is the control of rapid tool degradation which occurs during welding. This work reports a maiden study on tool degradation of high thickness ratio unequal thickness dissimilar material joints made between 6.3 mm thick AA2024-T3 and 2.5 mm thick AA7475-T7 plates. The degradation of friction stir welding tool made of T4 tool steel having tapered cylindrical pin and scrolled shoulder was analyzed. The geometry of tool (before and after welding) was compared; the degradation was categorized, characterized, and analyzed in the light of measured welding temperature, process forces, and process parameters. It was found that the pin undergoes significant degradation in the form of wear and deformation compared to the tool shoulder. The experimental results demonstrated that lower flow stresses caused by higher process temperature leads to lower tool wear and deformation, and vice versa. In addition to temperature and process forces, the surface tilt angle was found to significantly affect the pin deformation. The higher surface tilt angle caused an increase in tool wear and deformation.

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