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FRICTION STIR WELDING

FRICTION STIR WELDING. Introduction. Welding using friction as the major resource No filler material involved Welds created by, a) Frictional heating b) Mechanical deformation. History. Invented by TWI in 1991 in England 28 organizations worldwide use FSW. Friction Welding.

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FRICTION STIR WELDING

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  1. FRICTION STIR WELDING

  2. Introduction • Welding using friction as the major resource • No filler material involved • Welds created by, a) Frictional heating b) Mechanical deformation

  3. History • Invented by TWI in 1991 in England • 28 organizations worldwide use FSW

  4. Friction Welding • Heat from mechanical energy conversion Linear friction welding Rotary friction welding

  5. Friction Stir Welding Rotating probe provides friction heat and pressure which joins the material Sufficient downward force to maintain pressure and to create friction heat Sufficient downward force to maintain pressure and to create friction heat Shoulder which creates friction heatand welding pressure Probe which Stir the material

  6. Microstructure Analysis A. Unaffected material B. Heat affected zone (HAZ) C. Thermo-mechanically affected zone (TMAZ) D. Weld nugget (Part of thermo-mechanically affected zone)

  7. Microstructure analysis Optical micrographs of regions (a), (b) and (c) of the stir nugget.

  8. Joint Geometries • It can be used in all positions, • Horizontal • Vertical • Overhead • Orbital

  9. Material Suitability • Copper and its alloys • Lead • Titanium and its alloys • Magnesium alloys • Zinc • Plastics • Mild steel • Stainless steel • Nickel alloys

  10. Welding Steel using FSW

  11. Tools Parameters

  12. Common Tools Fixed Pin Tool Self Reacting Pin Tool Adjustable Pin Tool Retractable Pin Tool

  13. Some of the FSW Machines ESAB SuperStir TM machine FW28 ESAB Machine

  14. Advantages • Diverse materials: Welds a wide range of alloys, including previously un-weldable (and possibly composite materials) • Durable joints: Provides twice the fatigue resistance of fusion welds. • Versatile welds: Welds in all positions and creates straight or complex-shape welds • Retained material properties: Minimizes material distortion • Safe operation: Does not create hazards such as welding fumes, radiation, high voltage, liquid metals, or arcing • No keyholes: Pin is retracted automatically at end of weld • Tapered-thickness weld joints: Pin maintains full penetration

  15. Comparison with other joining processes FSW vs Fusion Welding FSW vsRivetting » Reduced Part Count » Reduced Production Time» Reduced Defect Rates » Increase in Load Carrying Capability» Improved Fracture Performance » Eliminates Consumables » Less Operator Dependent » Improved Mechanical Properties » Reduced Distortion » Reduced Defect Rate » Parent Metal Chemistry » Simplifies Dissimilar Alloy Welding » Fewer Process Variables » Eliminates Consumables » Reduces Health Hazard

  16. Disadvantages • Work pieces must be rigidly clamped • Backing bar required (except where self-reacting tool or directly opposed tools are used) • Keyhole at the end of each weld • Cannot make joints which required metal deposition (e.g. fillet welds)

  17. Barriers for FSW • Special clamping system necessary • Only for simple joint geometries (e.g. butt joint) • License required from TWI • Few applications in the construction industry • Corrosion protection is needed

  18. Future Developments • Laser-assisted friction stir welding • Possible use of induction coil and other mechanism

  19. Conclusion • An alternative to fusion welding • Advanced technologies are in the offing

  20. THANK YOU

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