Material Flow Modeling in Friction Stir Welding of AA6061-T6 Alloy and Study of the Effect of Process Parameters

To understand the friction stir welding process, it is very important to know the nature of the material flow in and around the tool. The process is a combination of both thermal as well as mechanical work i.e. it is a coupled thermo-mechanical process. Numerical simulations are very much essential in order to obtain a complete knowledge of the process as well as the physics underlying it. In the present work a model based approach is adopted in order to study material flow. A thermo-mechanical based CFD model is developed using a Finite Element package, Comsol Multiphysics. The fluid flow analysis is done. The model simultaneously predicts shear strain fields, shear strain rates and shear stress over the entire workpiece for the given conditions. The flow fields generated by the streamline plot give an idea of the material flow. The variation of dynamic viscosity, velocity field and shear strain fields with various welding parameters is studied. Finally the result obtained from the above mentioned conditions is discussed elaborately and concluded.

Authors:

• B. Saha Roy
• T. Medhi
• S. C. Saha

Keywords:

• AA6061-T6
• friction stir welding
• material flow
• CFD modelling.

References:

[1] W. M. Thomas, E. D. Nicholas, J. C. Needham, M. G. Murch, P.
Templesmith, and C. J. Dawes, G. B. Patent Application 9125978.8, UK
Patent Office, London,1991.
[2] R. Kovacevic, Welding Processes, In Tech., (Chapter 9), 2012.
[3] R. S. Mishra, and Z. Y. Ma, “Friction stir welding and processing”,
Mater Sci Eng R, 50, pp. 1–78, 2005.
[4] J. A. Schnieder, and A. C. Nunes, “Characterization of plastic flow and
resulting micro textures in a friction stir weld”, Metallurgical and
Materials Transaction, 35(4), 777–783, 2004.
[5] Ulysse, P., ‘Three-dimensional modelling of the friction stir-welding
process’, International Journal of Machine Tools & Manufacture,
42(14), pp. 1549–1557, 2002.
[6] H. Schmidt, and J. Hattel, “A local model for the thermomechanical
conditions in friction stir welding”, Modelling and Simulation in
Materials Science and Engineering, 13, pp. 77–93, 2005.
[7] G. Buffa, J. Hua, R. Shivpuri, and L. Fratini, “Design of the friction stir
welding tool using the continuum based FEM model”, Materials Science
& Engineering A, 419, pp. 381–388, 2006.
[8] K. Colligan, “Material flow behaviour during friction stir welding of
aluminum”, Welding Journal, Research Supplement, 78, pp. 229–237,
1999.
[9] T. U. Seidel, and A. P. Reynolds, “Visualization of the material flow in
AA2195 friction-stir welds using a marker insert technique”,
Metallurgical & Materials Transactions A, 32, pp. 2879–2884, 2001.
[10] H. Schmidt, T. L. Dickerson, and J. Hattel, “Material flow in butt
friction stir welds in AA2024-T”, Acta Materialia, 54, pp. 1199–1209,
2006.
[11] H. B. Schmidt, and J. H. Hattel, “Thermal and Material Flow modelling
of Friction Stir Welding using Comsol”, Excerpt from the Proceedings
of the COMSOL Conference, Hannover, 2008.
[12] J. A. Schneider, “Temperature Distribution and Resulting Metal Flow”,
Friction Stir Welding and Processing, ASM International, pp. 37-49,
2007.