National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Friction Stir

Professor D.I. Pantelis

Director of Shipbuilding Technology Laboratory School of Naval Architecture and Marine Engineering National Technical University of Athens Greece

1 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Friction Welding Methods

The methods are :

 Rotational Friction Welding:

Direct Drive Friction Welding

Inertia Friction Welding

 Linear Friction Welding or Linear Vibration Welding

 Orbital Friction Welding

 Radial Friction Welding

2 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Direct Drive Friction Welding

• The workpieces to be welded are clamped rigidly in a fixed unit and a rotating chuck assembly • The rotating part is accelerated to a predetermined rotational speed • During the rotation the fixed workpiece is pushed against the rotating part • The rotation and the axial force continue for a predetermined duration (until the production of the appropriate heat input) • Then, the rotation stops quickly and at “zero speed” the axial force increases until the end of the process Applications: valves for internal combustion engines, blades of turbines, pressure vessels… 3 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Inertia Friction Welding

• The workpieces to be welded are clamped rigidly in a fixed unit and a rotating chuck assembly • The rotating spindle (including the one part and any required flywheels) is accelerated to a predetermined rotational speed, storing the energy required for welding • The spindle is, then, disconnected from the drive source and the flywheel begins. Simultaneously, the ram assembly moves the non rotating part axially to force both workpieces together at a predetermined calculated thrust load • While the parts are thrust together , the produced friction converts kinetic energy stored in the rotating spindle and flywheel assemblies into heat at the interface of the parts, and finally into mechanical work of the plasticized metals

4 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Linear vibration welding

[http://www.twi-global.com] • One workpiece moves against the other in a linear direction • The friction force between the two parts generates heat which plasticizes their interface • A static load acting on the moving part promotes flow of the plasticized material, hence generating the weld

This method is fast and is usually applied on pieces with uniform surface and sufficient width.

5 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[M. MAALEKIAN, E. KOZESCHNIK, H.P. BRANTNER, H. Orbital friction welding CERJAK (2008). Finite Element Modeling of Orbital Friction Welding of Eutectoid Bars. METALLURGICAL AND MATERIALS TRANSACTIONS A, VOLUME 39A, 844-852]

• The center of the one component moves relative to the other component around a two-dimensional curve to provide the rubbing action • The two workpieces are rotated around their longitudinal axes in the same direction with the same angular speed • The two longitudinal axes are parallel with a small distance offset a. • When the motion of the components has stopped and, before the application of friction pressure, the parts are correctly aligned to form a weld.

It is used for fabrication and repair.

Its applications include butt welding and non-circular components, such as turbine blades. 6 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Radial friction welding [http://www.twi-global.com]

• Involves rotation and radial compression of a solid bevelled ring into a V-preparation provided by the pipe ends • A mandrel is located in the bore, at the weld location, to prevent collapse of the pipe ends and penetration of upset metal formed during the weld sequence. • The ring, made from a compatible material, is more sharply bevelled than the pipes to promote metal flow from the base of the weld reparation.

Applications:  Pipe welding  Wear resistant surfacing of shafts

7 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Friction stir welding

8 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Dawes C, Thomas W (1996). Friction stir process welds Principle of operation aluminum alloys. Weld. J., 75(3), 41-45]

Friction stir welding (FSW) is an innovative solid-state joining process which was invented and patented by “”, in 1991.

During FSW, a welding tool, which consists of a shoulder and a specially designed pin, is plunged into the plates to be welded, while rotating and advancing at a welding speed along the joint line until the plates have been butted together.

 The parts are clamped rigidly onto a backing bar in a manner that prevents the plates from being forced apart.  The length of the pin is slightly less than the weld depth required and the tool shoulder is in full contact with the work surface. 9 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis Process parameters

 Welding speed (mm/min)

 Rotational speed (RPM)

 Axial force (kN)

 Geometry and design of the welding tool

 Tool tilt angle

 Location of each material (AS, RS) when welding of dissimilar alloys is applied 10 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis FSW machines I-STIR VM of MTS

11 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [R. Nandan, T. DebRoy, H.K.D.H. Bhadeshia, Recent advances in friction-stir welding – Process, Welding Tools weldment structure and properties, Progress in Materials Science 53 (2008) 980–1023]

The welding tool comprises one of the most important parameters of the process, because it has a great effect on the material flow. The tool’s geometric characteristics and design significantly affect the properties of the weld.

12 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

BOBBIN TOOLS

 Tools consisting of 2 shoulders  Invented by the TWI  The forces on the machine and the clamping arrangement are small  Extremely small deformations due to uniform heat input

[M. Papadopoulos, S. Tavares, M. Pacchione, S. Pantelakis. Mechanical behaviour of AA 2024 friction stir overlap welds, International Journal of Structural Integrity, Vol. 4 No. 1, 2013 pp. 108-120.]

13 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [K. Kumar, S.V. Kailas, The role of friction stir welding tool on material Material Flow flow and weld formation, Materials Science and Engineering A 485 (2008) 367–374 The material flow during FSW is separated in two kinds of flow:

. Material flow due to pin: layer by layer . Material flow due to shoulder: material from retreating side(RS) is transferred through the shoulder surface at the top of the advancing side (AS).

pin-driven flow

layer by layer

shoulder-driven flow

by bulk 14 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [William J. Arbegast, Friction Stir Material Flow Welding and Processing: Introduction, MET 492-Special Topics, South Dakota School of Mines and Technology, 2005]

AS RS

 A part of the material is transferred from RS to AS (red arrows)  A volume of material from the upper part of AS and down from the left area of the flow arm is deposited to the right part of the zone (at AS) and to the middle of the weld nugget (white arrows)  Another volume of material of the extrusion zone at RS is shifted downwards and to the rear (yellow arrows)  The down part of the weld nugget is composed of the vortex zone (blue arrows) 15 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Mishra R. S. and Mahoney M. W., Friction Stir Welding and Processing, ASM International, Materials Park, Ohio, 2007] Zones:  Pre-heat  Initial deformation  Extrusion  Forging  Cool down

. The heat produced from the rotating motion of the tool preheats the area in front of the tool . The rotational motion of the tool creates the initial deformation zone. . In this zone, the metal is forced upward into the shoulder and then downward into the extrusion zone. . In the extrusion zone the metal front is moved around the pin tool to the exiting wake of the weld in the cavity being vacated by the pin as it moves forward. . The back part of the shoulder passes over the metal that exits from the extrusion zone and forges it, ensuring the welding. . Then, the metal cools down.

16 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis Characteristic microstructural zones

The solid-state nature of the FSW process, combined with its unusual welding tool, results in a highly characteristic microstructure. The major zones concerning the microstructure are as follows:

The stir zone or weld nugget

The thermo-mechanically affected zone (TMAZ)

The heat-affected zone (HAZ)

17 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Y.G. Kima, H. Fujii, T. Tsumura, T. Defects of FSW Komazaki, K. Nakata, Three defect types in friction stir welding of aluminum die casting , Materials Science and  Tunnel defect Engineering A 415 (2006) 250–254]

Due to insufficient heat input

 Groove like defect

18 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Caizhi Zhou, Xinqi Yang, Guohong Luan, Effect of oxide array on the property of friction stir welds, Scripta Materialia 54 (2006) 1515–  Κissing bond and lazy S 1520] Created by the fragmentation and distribution of the protective film of Al

alloys (Al2O3) into the WN

[Saad Ahmed Khodir, Toshiya Shibayanagi, Friction stir welding of dissimilar AA2024 and AA7075 aluminum alloys, Materials Science and Kissing Engineering B 148 (2008) 82–87] bond Created after dissimilar welding and is characterized by a heterogeneous microstructure

19 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[Y.G. Kima, H. Fujii, T. Tsumura, T. Komazaki, K. Nakata, Three defect types in friction stir welding of aluminum die casting alloy, Materials Science and  Defect due to abnormal stirring Engineering A 415 (2006) 250–254]

It is owed to the non-uniform in thickness thermal distribution encountered at high rotational and welding speeds.

20 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[Y.G. Kima, H. Fujii, T. Tsumura, T. Komazaki, K. Nakata, Three defect types in friction stir welding of aluminum die casting alloy, Materials Science and Engineering A 415 (2006) 250–254]  Flash

Created by excessive heat input. Its presence results to reduced thickness of the weld nugget area.

21 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Advantages

 It is a fully automated method - Robotic welding.

 Applicability in all welding positions.

 No special preparation of the workpieces is required (e.g. bevel).

 Excellent mechanical properties of the welds (tensile, fatigue and bending).

 Small deformations, even for long welds.

22 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

 Ability for welding materials whose is low when using conventional welding techniques (AA 2XXX, AA 7XXX and dissimilar materials).

 No consumables - no filler or gas shield is required for aluminum.

 Lower setup costs and less training.

 Energy efficient.

 Environmentally friendly and safer than conventional techniques, due to the absence of toxic fumes.

23 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis Disadvantages and limitations of FSW

 Exit hole left when tool is withdrawn.

 Large down forces are required, hence, heavy-duty clamping is necessitated to hold the plates together.

 Lower welding speed than some conventional welding techniques.

 Very expensive equipment.

 Low wear resistance of tool when welding high strength alloys.

24 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

The main materials which have been welded using FSW are:

A) Al alloys

B)

C) Ti alloys

D) Cu alloys

25 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis Α) FSW of Al alloys  FSW was firstly applied to Al alloys.  Nowadays, most of the problems regarding FSW of Al alloys (for thicknesses up to 14mm with one pass) have been resolved.  Conventional steel tools can weld about 1000m of Al alloys.

• 1ΧΧΧ Excellent mechanical FSW properties which are Non thermally treated • 5ΧΧΧ usually higher than those of the parent material • 2ΧΧΧ  Condition O:

FSW Improvement of mechanical • 6ΧΧΧ Thermally treated properties in the weld area due to precipitation mechanisms • 7ΧΧΧ  Condition T : Improved mechanical Degradation of mechanical properties compared to the properties in the weld nugget and conventional welding mainly in the HAZ, due to methods dissolution of the precipitates 26

SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [PhD thesis in progress, N. Daniolos, STL-NTUA] Dynamic re-crystallized/ Example of microstructure of FSWed 5083-H111 recovery area

Parent WN Material

ΗΑΖ TMAZ

27 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[PhD thesis in progress, N. Daniolos, STL-NTUA]

Example of microhardness distribution  5083 in H111 condition

28 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[PhD thesis in progress, N. Daniolos, STL-NTUA]

Example of microhardness distribution  6082 in T6 condition

29 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Mishra R. S. and Mahoney M. W., Friction Stir Welding and Processing, ASM International, Materials Park, Ohio, 2007] Mechanical properties of FSWed ΑΑ6063-Τ5

30 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [R. Nandan, T. DebRoy, H.K.D.H. Bhadeshia, Recent advances in friction-stir welding – Process, weldment structure and properties, Progress in Materials Science 53 (2008) 980–1023] Β) FSW of steels FSW of steels presents many difficulties due to the following:

 The tool material must have adequate wear and thermal resistance.

 The vast majority of steels demands a large number of experiments, in order to optimize the welding conditions for each application.

 The effects of phase transformations during FSW have not been studied in a sufficient depth, yet.

 There are many other techniques that can weld steels satisfactorily and reliably.

 Ongoing research is carried out to overcome various difficulties.

31 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Mishra R. S. and Mahoney M. W., Friction Stir Welding and Processing, ASM International, Materials for welding tools Materials Park, Ohio, 2007]

 Refractory materials Weld: . Tools of W and W+Re  Low carbon steels  C-Mn steels Problems : short lifetime, fragmented  Austenitic stainless steels particles from the tool are  Ferritic stainless steels distributed in the WN.

 Wear resistant materials Tested for FSW in: . Tools of boron and silicon nitride  Low carbon steels  C-Mn steels  High strength steels Problems: Short lifetime which is continuously  HSLA improved:  Steels for high strength tubes 1-4m for 316L 80m for 1018 steel  Austenitic stainless steels  Duplex stainless steels Limitation in maximum weld depth: max 6 - 10mm  Dual phase steels

32 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [HILDA – High Integrity Low Distortion Assembly FP7 European Project]

One of the greatest advantages of FSW of steels is the very low distortions

DH36 weld Thickness: 6mm Length: 2m

33 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [MOSAIC: Materials On-board: Steel Advancements and Integrated Composites-FP7 European Project]

. The main problem for FSW of steels is the tool material. It is required a material capable of withstanding immersion in plasticized steel at temperatures in excess of 1200o C, whilst subject to forces and bending stresses which can be in excess of 80kN.

. The current best welding tool for FSW of steels is a hybrid design utilizing PCBN in a W-Re binder, which is very expensive, currently short lived and is available from only one supplier.

 Friction stir welds of DH36 steel (6mm thickness) with better mechanical properties (tensile strength, hardness, toughness, fatigue strength) than the parent material and with indications of a very good corrosion resistance have recently been produced.

34 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [MOSAIC: Materials On-board: Steel Advancements and Integrated Composites-FP7 European Project]

 It has been found that:

 Dissimilar types of steels can be welded (including stainless steels and low carbon steels)  ODS steels can be welded, which are considered unweldable by techniques  These alloys can easily produce welds without defects

 The improved weld properties of FSW of steel, in combination with reduction in distortion and the ability to weld grades of steel that were considered challenging or impossible to weld by conventional techniques, mitigated the current high cost of the process.

35 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Mishra R. S. and Mahoney M. W., Friction Stir Welding and Γ) FSW of Ti alloys Processing, ASM International, Materials Park, Ohio, 2007] FSW of Ti alloys comprises a research area of high interest.

Ti alloys which have been FS welded are:

 Commercially pure Ti alloys

 Ti-6Al-4V

 Ti-15V-3Cr-3Al-3Sn

 Beta 21-S

Problem Materials for welding tools: Ti is an excellent solvent in high temperatures for many of the Refractory materials(W, W-Re) synthesis materials of the tool. Mo alloys Therefore, strategies for the reduction

Robust cermets (WC/Co) of wear and deformation of the tools should be developed. 36 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Mishra R. S. and Mahoney M. W., Friction Stir Welding and Processing, ASM International, Materials Park, Ohio, 2007] Microhardness distribution of FSWeld Ti-6Al-4V

Tensile strength of FSWeld Ti-6Al-4V

37 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis - Mishra R. S. and Mahoney M. W., Friction Stir Welding and Processing, ASM International, Materials Park, Ohio, 2007 Γ) FSW/FSP of Cu alloys - R. Nandan, T. DebRoy, H.K.D.H. Bhadeshia, Recent advances in friction-stir welding – Process, weldment structure and properties, Progress in It is difficult to weld Cu alloys with Materials Science 53 (2008) 980–1023 conventional techniques, due to their - Research program of STL-NTUA] high thermal diffusivity.

Some of the Cu alloys which have been welded using FSW, so far, are:

 Pure Cu

 Cu-9.4Al-5Ni-4Fe

 Cu-Al-5Zn-5Sn

 Cu-25Ni

The mechanical properties (e.g. hardness) of the WN depend on the microstructure, which in turn is affected by the grain size of the parent material.

38 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[Mishra R. S. and Mahoney M. W., Friction Stir Welding and Processing, ASM International, Materials Park, Ohio, 2007]

Cast Ni-Al bronze

[Master thesis of I. Moulakaki, STL-NTUA]

Pure Cu

39 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

OTHER RESEARCH AREAS IN PROGRESS

1. Hybrid friction stir welding

2. Reinforcement of FS welds with addition of nanoparticles (SiC, TiC, CNT’s)

3. Repair welding using FSW

4. Friction Stir

40 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis • K. Feldman, G. Kohn, A. Stern, On Laser Assisted-Friction Stir Welding, Welding Conference 2006, Herzelia. • 2001 NASA-ODU American Society for Engineering Education, Laser-Assisted Stir Welding of 25mm Thick HSLA-65 Plate, 2002. • Shivani Daftardar B.E, Laser Assisted Friction Stir Welding: Finite Volume Method and Metaheuristic Optimization, Maharashtra Institute of Technology, India, May 2009.

1.Hybrid friction stir welding

FSW assisted by laser

• Suitable for welding thick plates.

• The preheating provided by the laser reduces the stresses which damage the tool, the load received by the machine and its components and allows the application of higher welding speeds.

41 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[PhD thesis in progress, P. Karakizis, STL-NTUA, EU FP7 Project “Enhancing structural efficiency through novel dissimilar material joining techniques” (SAFEJOINT)]

2. Reinforcement of similar and dissimilar FS weld with addition of nanoparticles (SiC, TiC, CNT’s) Addition of nanoparticles

For their addition, a groove is created after the appropriate .

Groove geometry

42 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Microhardness distribution [PhD thesis in progress, P. Karakizis, STL-NTUA] Effect of nanoparticles in microhardness distribution Materials to be welded: AA5083-H111 and AA6082-T6

43 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis Study of mechanical properties [PhD thesis in progress, P. Karakizis, STL-NTUA] Effect of nanoparticles in mechanical properties

Young’s Yield stress UTS Elongation Specimen Modulus (MPa) (MPa) (%) (GPa) Specimen no 4 78 138 217 5 (with SiC) Specimen no 5 65 140 193 3 (without SiC) 44 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [HILDA – High Integrity Low Distortion Assembly FP7 European Project]

3. Repair welding using FSW

 Easy to repair MIG welds of Al alloys using FSW.

 Boeing has used FSW to repair MIG weld in fuel vessel.

45 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Q. Yang, S. Mironov, Y.S. Sato, K. Okamoto, 4. Friction Stir Spot Welding Material flow during friction stir spot welding, Materials Science and Engineering A, 527 (2010) 4389–4398]

Principle of operation

Produced weld

46 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

 It is used for dissimilar welding.

 This process has been developed and used in the automotive industry (eg Mazda RX8), due to the increasing use of Advancing High Strength Steels.

 Existence of potential benefits compared to resistance spot welding.

 Optimization is required, regarding the strength of the welds.

 The tools of PCBN, Si3N4 and W-Re exhibit relatively satisfactory wear resistance.

47 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [http://www.twi-global.com] APPLICATIONS OF FSW Railway Industry

 Rolling stock of railways, underground carriages, trams

 Container bodies

 Railway tankers

Land Transportation

 Engine and chassis cradles  Fuel tankers

 Wheel rims  Caravans

 Truck bodies & tail lifts for lorries  Buses and airfield transportation vehicles  Mobile cranes

 Armour plate vehicles

48 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [http://www.twi-global.com]

Aerospace Industry

FSW can be applied for:

 Wings, fuselages, empennages

 Cryogenic fuel tanks for space vehicles

 External throw away tanks for military aircraft

 Military and scientific rockets

 Repair of faulty MIG welds

49 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [www.twi-global.com]

Ναυπηγική Τεχνολογία και Θαλάσσιες κατασκευές FSW can be used for welding of the following:

 Panels for decks, sides, bulkheads and floors

 Helicopter landing platforms

 Hulls and superstructures

 Refrigeration plant

50 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[Application of friction stir welding in the shipbuilding Examples of applications industry, Stephan Kallee, presented at Lightweight in Shipbuilding Construction - Latest Developments, The Royal Institution of Naval Architects , London, 24 & 25 Feb 2000]

FSW catamaran side-wall with cut-out Prefabricated FSW panel for half the width sections for windows. of the superstructure of a cruise liner.

51 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[Application of friction stir welding in the Examples of applications shipbuilding industry, Stephan Kallee, presented in Shipbuilding at Lightweight Construction - Latest Developments, The Royal Institution of Naval Architects , London, 24 & 25 Feb 2000]

Prefabricated FSW panel for a catamaran sidewall, rolled for road transport.

Prefabricated FSW panel for a catamaran sidewall. Straight panel for ship transportation.

52 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis [Friction stir welding of ships, Fred Examples of applications Delany, Stephan W Kallee and Mike J Russell, 2007 International Forum on Welding in Shipbuilding Technologies in the Shipping Industry (IFWT) Held in conjunction with the Beijing Essen Welding and Cutting Fair in Shanghai, 16-19 June 2007 ]

Fosen Mek's cruise ship 'The ' contains friction stir welded decks. Marine Aluminium's prefabricated FSW deck panels for 'The World' cruise ship. 53 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

[Friction stir welding of aluminium ships, Fred Delany, Examples of applications Stephan W Kallee and Mike J Russell, 2007 International in Shipbuilding Forum on Welding Technologies in the Shipping Industry (IFWT) Held in conjunction with the Beijing Essen Welding and Cutting Fair in Shanghai, 16-19 June 2007]

FSW of 5m x 12m large aluminum FSW used on Chinese aluminium alloy ship panels at CFSWT. ships for various export markets.

54 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis

Examples of applications in Shipbuilding

'Type 022' new-generation stealth 'Seven Seas Navigator', a cruise ship with missile fast attack craft (FAC) extensive friction stir welding in the superstructure

[Friction stir welding of aluminium ships, Fred Delany, [Progress in friction stir welding of aluminium and Stephan W Kallee and Mike J Russell, 2007 International steel for marine applications, R Johnson and P L Forum on Welding Technologies in the Shipping Industry Threadgill, RINA Conference: Advanced Marine (IFWT) Held in conjunction with the Beijing Essen Materials: Technology and Applications. October 2003] Welding and Cutting Fair in Shanghai, 16-19 June 2007] 55 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis Conclusions

The FSW is a promising technique providing many benefits in terms of strength, productivity and safety.

Regarding aluminum alloys:

The FSW has been established and studied in depth for aluminum alloys with a thickness up to 14 mm.

 The aim is to apply FSW for welding thicker aluminum alloys .

56 SNAME, Greek Section, Technical Meeting, 29 May 2014 National Technical University of Athens School of Naval Architecture and Marine Engineering Shipbuilding Technology Laboratory Professor D.I. Pantelis Conclusions Regarding steels:

The major benefits of the procedure in steels are the excellent microstructural properties and fatigue strength, combined with extremely low distortions.

The main challenges that must be solved for the extensive application of FSW in steels include:

• Improvement of productivity (welding speed, tool strength, cost)

• Extension of target application (welding geometry, types of steel, thickness)

• Strategy for Quality Assurance

57 SNAME, Greek Section, Technical Meeting, 29 May 2014