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Metallurgical and Materials Transactions A

, Volume 32, Issue 5, pp 1189–1200 | Cite as

A process model for friction stir welding of age hardening aluminum alloys

  • Ø. Frigaard
  • Ø. Grong
  • O. T. Midling
Article

Abstract

In the present investigation, a numerical three-dimensional (3-D) heat flow model for friction stir welding (FSW) has been developed, based on the method of finite differences. The algorithm, which is implemented in MATLAB 5.2, is provided with a separate module for calculation of the microstructure evolution and the resulting hardness distribution. The process model is validated by comparison with in-situ thermocouple measurements and experimental hardness profiles measured at specific time intervals after welding to unravel the strength recovery during natural aging. Furthermore, the grain structure within the plastically deformed region of the as-welded materials has been characterized by means of the electron backscattered diffraction (EBSD) technique in the scanning electron microscope (SEM). Some practical applications of the process model are described toward the end of the article.

Keywords

Welding Material Transaction Friction Stir Welding Welding Speed Friction Stir Welding 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Appendix I List of Symbols

A0

material constant related to the potency of the heterogeneous nucleation sites in actual alloy (J mol−1)

a

thermal diffusivity (m2 s−1)

Co

total alloy content (wt pct)

Cmo

matrix solute content in stabilised base material (wt pct)

Cp

solute concentration within the particle (wt pct)

D0

diffusion coefficient (m2 s−1)

ds

subgrain diameter (m)

dx, dy, dz

discretization parameters in x, y, and z directions (m)

f0

initial volume fraction of precipitates in base material

fm

maximum possible volume fraction of hardening precipitates that can form at absolute zero

HVmax

hardness in the temper condition (VPN)

HVmin

hardness in the fully reverted condition (VPN)

M

interfacial torque (Nm)

N

rotational speed (rot·s−1)

P

pressure (Pa)

P(r)

pressure distribution across the interface (Pa)

Q

activation energy for diffusion (J mol−1)

Qd

activation energy for diffusion of Mg in Al (J mol−1)

Qs

activation energy for diffusion of the less mobile constitutive atom of the precipitates (J mol−1)

q0

net power (W)

R

tool radius (m)

r

two-dimensional radius vector (m)

r0

initial particle radius (m)

Smax0

hardness or strength in age-hardened base material (VPN or Pa)

Smin0

hardness or strength in fully reverted condition (VPN or Pa)

T

temperature (°C or K)

Tmax

maximum temperature (°C or K)

Ts

peak temperature (°C or K)

Ts

phase boundary solvus temperature (°C or K)

t

time (s)

t*r1

maximum hold time for complete dissolution at reference temperature (s)

t*r2

time taken to precipitate a certain fraction of β′-Mg2Si at a chosen reference temperature (s)

v

welding speed (m s−1)

V

unit volume (m3)

Vm

molar volume (m3 mol−1)

x

x-axis/welding direction (m)

y

y-axis/transverse direction (m)

Zh

Zener-Hollomon parameter (s−1)

z

z-axis/thickness direction

ρc

volume heat capacity (J m−3 °C−1)

ɛ

strain rate (s−1)

γ

interfacial energy (J m−2)

μ

friction coefficient

ω

angular velocity (rad/s)

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References

  1. 1.
    O.T. Midling: Proc. 4th Int. Conf. on Aluminium Alloys—Their Physical and Mechanical Properties, Atlanta, GA, Sept. 1994, T. Sanders and E.A. Starke, eds., Georgia Institute of Technology School of Material Science and Engineering, Atlanta, GA, vol. I, pp. 451–58.Google Scholar
  2. 2.
    C.J. Dawes and W.M. Thomas: Welding J., 1996, vol. 75 (3), pp. 41–45.Google Scholar
  3. 3.
    O.T. Midling and H.G. Johansen: 6th Int. Aluminium Technology Seminar & Exposition, ET96, Chicago, IL, May 14–17, 1996, R.I. Werner, R. Peacock, and S. James, eds., Aluminium Association and the Aluminium Extruders Council, IL, USA, vol. II, pp. 451–58.Google Scholar
  4. 4.
    O.T. Midling: Proc. Aluminium 97 Conf., Sept. 24–25, 1997, Essen, Germany, Argus Business Media Ltd., United Kingdom, and Rumrest GmbH, Germany, DMG Business Media Ltd., London, United Kingdom, pp. 26/1–26/6.Google Scholar
  5. 5.
    C.J. Dawes: Welding Met. Fabrication, 1995, vol. 63, pp. 13–16.Google Scholar
  6. 6.
    C.J. Dawes: Proc. 6th Int. Symp. on “The Role of Welding Science and Technology in the 21st Century”, Nagoya, Japan, 1996, Japan Welding Society, Tokyo, Japan, pp. 711–18.Google Scholar
  7. 7.
    S. Kallee, D. Richardson, and I. Henderson: Schweissen & Schneiden (Welding & Cutting), 1997, vol. 49, pp. 904–09.Google Scholar
  8. 8.
    K.E. Knipström and B. Pekkari: Welding J., 1997, vol. 76, pp. 55–57.Google Scholar
  9. 9.
    J. Hagström and R. Sandström: Sci. Technol. Welding Joining, 1997, vol. 2, pp. 199–208.Google Scholar
  10. 10.
    M. Enomoto: J. Light Met. Welding Constr., 1998, vol. 36, pp. 25–29.Google Scholar
  11. 11.
    W.M. Thomas and E.D. Nicholas: Mater. Desember, 1997, vol. 18 (4–6), pp. 267–73.Google Scholar
  12. 12.
    M.B. Ellis and M. Strangwood: Mater. Sci. Technol., 1996, vol. 12, pp. 970–77.Google Scholar
  13. 13.
    C.G. Rhodes, M.W. Mahoney, W.H. Bingel, R.A. Spurling, and C.C. Bamton: Scripta Mater., 1997, vol. 36, pp. 69–75.CrossRefGoogle Scholar
  14. 14.
    M.W. Mahoney, C.G. Rhodes, J.G. Flintoff, R.A. Spurling, and W.H. Bingel: Metall. Mater. Trans. A, 1998, vol. 29A, pp. 1955–64.CrossRefGoogle Scholar
  15. 15.
    G. Liu, L.E. Murr, C.-S. Niou, J.C. McClure, and F.R. Vega: Scripta Mater., 1997, vol. 37, pp. 355–61.CrossRefGoogle Scholar
  16. 16.
    L.E. Murr, G. Liu, and J.C. McClure: J. Mater. Sci., 1998, vol. 33, pp. 1243–51.CrossRefGoogle Scholar
  17. 17.
    Y.S. Sato, H. Kokawa, M. Enomoto, and S. Jogan: Metall. Mater. Trans. A, 1999, vol. 30A, pp. 2429–37.Google Scholar
  18. 18.
    Y.S. Sato, H. Kokawa, M. Enomoto, S. Jogan, and T. Hashimoto: Metall. Mater. Trans. A, 1999, vol. 30A, pp. 3125–30.Google Scholar
  19. 19.
    M.J. Russel and H.R. Shercliff: Proc. Inalco ’98 7th Int. Conf., TWI, Cambridge, United Kingdom, April 16, 1998, The Welding Institute (TWI), Cambridge, United Kingdom, vol. 2, pp. 185–95.Google Scholar
  20. 20.
    A.P. Reynolds, W.D. Lockwood, and T.U. Seidel: Proc. 7th Int. Conf. on Aluminium Alloys—Their Physical and Mechanical Properties, Charlottesville, VA, Apr. 2000, E.A. Starke, T.H. Sanders, and W.A. Cassada, Trans Tech Publications, Zuerich, Switzerland, NH, Part 3, pp. 1719–24.Google Scholar
  21. 21.
    Ø. Grong: Metallurgical Modelling of Welding, 2nd ed., The Institute of Materials, London, 1997.Google Scholar
  22. 22.
    B.I. Bjørneklett, Ø. Grong, O.R. Myhr, and A.O. Kluken: Acta Mater., 1998, vol. 46, pp. 6257–66.CrossRefGoogle Scholar
  23. 23.
    B.I. Bjørneklett, Ø. Grong, O.R. Myhr, and A.O. Kluken: Sci. Technol. Welding Joining, 1999, vol. 4, pp. 161–69.CrossRefGoogle Scholar
  24. 24.
    O.R. Myhr and Ø. Grong: Acta Metall. Mater., 1991, vol. 39, pp. 2693 and 2703–08.CrossRefGoogle Scholar
  25. 25.
    B.I. Bjørneklett, Ø. Grong, O.R. Myhr, and A.O. Kluken: Metall. Mater. Trans. A, 1999, vol. 30A, pp. 2667–77.Google Scholar
  26. 26.
    O.R. Myhr, Ø. Grong, S. Klokkehaug, H.G. Fjær, and A.O. Kluken: Sci. Technol. Welding Joining, 1997, vol. 2, pp. 245–53.Google Scholar
  27. 27.
    O.R. Myhr, Ø. Grong, S. Klokkehaug, H.G. Fjær, and A.O. Kluken: Welding J., 1998, vol. 77, pp. 286–92.Google Scholar
  28. 28.
    O.R. Myhr, Ø. Grong, S. Klokkehaug, H.G. Fjær, and A.O. Kluken: Proc. 5th Int. Conf. on Trends in Welding Research, Pine Mountain, GA, June 1–5, 1999, ASM INTERNATIONAL, Materials Park, OH, 1999, pp. 233–38.Google Scholar
  29. 29.
    Ø. Frigaard: Ph.D. Thesis, Norwegian University of Science and Technology, Trondheim, 1999, IME-Report No. 1999–5.Google Scholar
  30. 30.
    H.S. Carslaw and J.C. Jaeger: Conduction of Heat in Solids, Oxford University Press, Oxford, United Kingdom, 1959.Google Scholar
  31. 31.
    O.T. Midling and Ø. Grong: Acta Metall. Mater., 1994, vol. 42, pp. 1595–1609 and 1611–22.CrossRefGoogle Scholar
  32. 32.
    B. Crossland: Friction Welding. Cont. Phys., 1971, vol. 12 (6), pp. 559–74.Google Scholar
  33. 33.
    H.S. Kong and M.F. Ashby: “Case Studies in the Application of Temperature Maps for Dry Sliding,” Engineering Department Report, Cambridge University, Cambridge, United Kingdom, 1991.Google Scholar
  34. 34.
    J. Hjelen: Proc. 3rd Int. Conf. on Aluminium Alloys—Their Physical and Mechanical Properties, Trondheim, Norway, June 1992, The Norwegian Institute of Technology, Trondheim, vol. II, pp. 408–13.Google Scholar
  35. 35.
    Friction Data Guide: An Engineering Study of Coefficient of Friction of Materials and Coatings, Slide-chart presentation from General Magnaplate Corp., Linden, NJ, 1988.Google Scholar
  36. 36.
    O. Reiso: Proc. 3rd Int. Aluminium Extrusion Technology Seminar, Atlanta, GA, 1984, Aluminium Association, Washington, DC, 1984, vol. 1, pp. 31–40.Google Scholar
  37. 37.
    J.E. Hatch: Aluminium, Properties and Physical Metallurgy, ASM, Metals Park, OH, 1984.Google Scholar
  38. 38.
    P.E. Drønen and N. Ryum: Metall. Mater. Trans. A, 1994, vol. 25A, pp. 521–30.Google Scholar
  39. 39.
    Ø. Frigaard, Ø. Grong, B. Bjørneklett, and O.T. Midling: Proc. 1st Int. Symp. on Friction Stir Welding, Thousand Oaks, CA, June 1999, The Welding Institute (TWI), Cambridge, United Kingdom, 1999.Google Scholar
  40. 40.
    O.V. Flores, C. Kennedy, L.E. Murr, D. Brown, S. Pappu, B.M. Nowak, and J.C. McClure: Scripta Mater., 1998, vol. 38 (5), pp. 703–08.CrossRefGoogle Scholar
  41. 41.
    H.S. Yang: Proc. 6th Int. Conf. on Aluminium Alloys, ICAA-6, Toyohashi, Japan, July 5–10, 1998, T. Sato, S. Kumai, T. Kobayashi, and Y. Murakami, eds., The Japan Institute of Light Metals, Tokyo, vol. 3, pp. 1483–88.Google Scholar
  42. 42.
    A.F. Norman, I. Brough, and P.B. Pragnell: Proc. 7th Int. Conf. on Aluminium Alloys—Their Physical and Mechanical Properties, Charlottesville, VA, Apr. 2000, E.A. Starke and W.A. Cassada, eds., Trans Tech Publications, Zuerich, Switzerland, NH, Part 3, pp. 1713–18.Google Scholar
  43. 43.
    F.J. Humphereys and M. Hatherly: in Recrystallization and Related Annealing Phenomena, Pergamon, Elsevier Science Ltd., Oxford, United Kingdom, 1996, pp. 363–92.Google Scholar
  44. 44.
    H.J. McQeen and J.J. Jonas: Plastic Deformation of Materials, Academic Press, New York, NY, 1975, vol. 6, pp. 393–493.Google Scholar
  45. 45.
    Ø. Frigaard, B.I. Bjørneklett, Ø. Grong, O.R. Myhr, and O.T. Midling: Proc. 6th Int. Conf. on Aluminium Alloys—Their Physical and Mechanical Properties, Toyohashi, Japan, July 1998, T. Sato, S. Kumai, T. Kobayashi, and Y. Murakami, eds., The Japan Institute of Light Metals, Tokyo, 1998, vol. III, pp. 1477–82.Google Scholar

Copyright information

© ASM International & TMS-The Minerals, Metals and Materials Society 2001

Authors and Affiliations

  • Ø. Frigaard
    • 1
  • Ø. Grong
    • 2
  • O. T. Midling
    • 3
  1. 1.the Material Command, Analytical LaboratoryRoyal Norwegian AirforceKjellerNorway
  2. 2.Department of Materials Technology and ElectrochemistryThe Norwegian University of Science and TechnologyTrondheimNorway
  3. 3.Hydro Aluminium Maritime ASAvaldsnesNorway

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