Predicting Residual Stresses in Friction Stir Welding of Aluminum Alloy 6061 Using an Integrated Multiphysics Model

Abstract:

Experimental results in the literature show that there are two flow areas of material during the friction stir welding (FSW) process [1]; namely the “pin-driven flow” and the “shoulder-driven flow”. These areas should completely join together to create a weld with no defect. First, in order to numerically predict the local distribution of flow stress around the pin as well as the temperature, strain, and strain rate fields during FSW, a two-dimensional steady-state Eulerian multiphysics finite element model has been employed in this work for aluminum alloy 6061using the COMSOL software. In this model, the non-Newtonian flow mode of computational fluid dynamics (CFD) module, general heat transfer mode of the heat transfer module, and the plain stress mode of the structural mechanics module of the software have been coupled. Slip/stick condition between the tool and workpiece, frictional and deformation heat sources, the convectional heat transfer in the workpiece, the solid mechanics-based viscosity definition, the temperature-dependent physical properties and the Zener-Hollomon- based thermo-visco-plastic mechanical properties with a cut-off temperature of 582oC were considered. Next, the thermal history during the process predicted by the model was used as input for an elasto-visco-plastic analysis to estimate the local residual stresses distribution due to the workpiece thermal expansion effect. Finally, the predicted longitudinal and transverse residual stresses were verified by comparing to experimental data.

• Periodical: Materials Science Forum (Volumes 768-769)
• Pages: 682-689
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.768-769.682
• Online since: September 2013
• Authors: Mohamadreza Nourani, Abbas S. Milani, Spiro Yannacopoulos, Claire Yu Yan
• Keywords: AA6061 Aluminum Alloy, Friction Stir Welding (FSW), Integrated Multiphysics Modeling, Residual Stress

References

[1] K. Kumar, S.V. Kailas, The role of friction stir welding tool on material flow and weld formation. Mater. Sci. & Eng. A. 485 (2008) 367-374.

DOI: 10.1016/j.msea.2007.08.013

[2] W.M. Thomas, E.D. Nicholas, J.C. Needham, M.G. Murch, P. Temple-Smith, C.J. Dawes, Friction Welding. Cambridge, UK: The Welding Institute TWI Patent Application No 91259788 (1991).

[3] M.M. Shtrikman, Current state and development of friction stir welding Part 3, Weld. Inter. 22 (2008) 806-815.

DOI: 10.1080/09507110802593620

[4] M. Nourani, A. S. Milani, S. Yannacopoulos, Taguchi optimization of process parameters in friction stir welding of 6061 aluminum alloy: a review and case study, Eng. 3 (2011) 144-155.

DOI: 10.4236/eng.2011.32017

[5] W. Woo, H. Choo, D.W. Brown, Z. Feng, P.K. Liaw, Angular distortion and through-thickness residual stress distribution in the friction-stir processed 6061-T6 aluminum alloy, Mater. Sci. Eng. A. 437 (2006) 64-69.

DOI: 10.1016/j.msea.2006.04.066

[6] X. Qin, P. Michaleris, Thermo-elasto-viscoplastic modelling of friction stir welding, Sci Tech Weld Join. 14 (2009) 640-649.

DOI: 10.1179/136217109x12464549883457

[7] Z. Feng, X.L. Wang, S.A. David, P.S. Sklad, Modeling of residual stress and property distribution in friction stir welds of aluminium ally 6061-T6, J. Sci. Technol. Weld. Join. 12 (2007), 348-356.

DOI: 10.1179/174329307x197610

[8] P. A. Colegrove, H. R. Shercliffa, 3-Dimensional CFD Modelling of flow round a threaded friction stir welding tool profile, J. Mater. Process. Technol. 169 (2005) 320-327.

DOI: 10.1016/j.jmatprotec.2005.03.015

[9] H.K. Versteeg, W. Malalasekera,. An Introduction to Computational Fluid Dynamics the Finite Volume Method, Longman Scientific & Technical, New York, (1995).

[10] M. Nourani, A.S. Milani, S. Yannacopoulos,. A new approach to measure stain during friction stir welding using visioplasticity, Proc of ASME Conference, Denver, (2011) 1-7.

DOI: 10.1115/imece2011-62061

[11] S. Xu, X. Deng, A study of texture patterns in friction stir welds. Acta Materialia. 56 (2008) 1326-1341.

DOI: 10.1016/j.actamat.2007.11.016

[12] H. Atharifar, D. Lin, R. Kovacevic, Numerical and experimental investigations on the loads carried by the tool during friction stir welding, J Mater Eng Perform. 18 (2009) 339-350.

DOI: 10.1007/s11665-008-9298-1

[13] R. Lewis, P. Nithiarasu, K. Seetharamu,. Fundamentals of the Finite Element Method for Heat and Fluid Flow, John Wiley & Sons Ltd, New York, (2004).

DOI: 10.1002/0470014164

[14] J.H. Hattel, H. Schmidt, C. Tutum,. Thermomechanical modelling of friction stir welding. Trends in Welding Research, Proceedings of the 8th International Conference, ASM, Stan A. David Ed., (2009) 1-10.

[15] C.M. Sellars, W.J.M. Tegart, On the mechanism of hot deformation, Acta Metall. 14 (1966) 1136-1138.

[16] T. Sheppard, D. Wright, Determination of flow stress: Part 1 constitutive equation for aluminum alloys at elevated temperatures, Met. Technol. 6 (1979) 215-223.

DOI: 10.1179/030716979803276264

[17] P.A. Colegrove, H.R. Shercliff, R. Zettler, Model for predicting heat generation and temperature in friction stir welding from the material properties, Sci Tech Weld Join. 12 (2007) 284-298.

DOI: 10.1179/174329307x197539

[18] K. Tello, A. Gerlich, P. Mendez, Constants for hot deformation constitutive models for recent experimental data, Sci Tech Weld Join. 15 (2010) 260-266.

DOI: 10.1179/136217110x12665778348380

[19] M. Nourani, A. S. Milani, S. Yannacopoulos, and C. Yan, An integrated multiphysics model for friction stir welding of 6061 Aluminum alloy, submitted to Sci Tech Weld Join. (2012).

DOI: 10.1260/1750-9548.8.1.29

[20] T. Long, A.P. Reynolds, Parametric studies of friction stir welding by commercial fluid dynamics simulation, Sci Tech Weld Join. 11 (2006) 200-209.

DOI: 10.1179/174329306x85985

[21] M. Riahi, H. Nazari,. Analysis of transient temperature and residual thermal stresses in friction stir welding of aluminum alloy 6061-T6 via numerical simulation. Inter. J. Adv. Manuf. Tech. 55 (2011) 143-152.

DOI: 10.1007/s00170-010-3038-z

[22] J. Simo, T. Hughes, Computational Inelasticity, Springer-Verlag, New York, (1998).

[23] W. Woo, Z. Feng, X.L. Wang, D.W. Brown, B. Clausen, K. An, H. Choo, C.R. Hubbard, S.A. David, In situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminium alloy, Sci Tech Weld Join. 12 (2007).

DOI: 10.1179/174329307x197548

[24] X.L. Wang, Z. Feng, S.A. David, S. Spooner, C.R. Hubbard, Neutron diffraction study of residual stresses in friction stir welds. In: Sixth international conference on residual stresses. IOM Comunications, London, (2000) 1408-1414.

DOI: 10.2172/672109

[25] C. Gallais, A. Simar, D. Fabregue, A. Denquin, G. Lapasset, Multiscale analysis of the strength and ductility of AA 6056 aluminum friction stir welds, Metall. Mater. Trans. A. 38A (2007) 964-981.

DOI: 10.1007/s11661-007-9121-x