Effects of Tool Design and Friction Stir Welding Parameters on Weld Morphology in Aluminum Alloys

Abstract:

Friction stir welding (FSW) is a complex thermo-mechanical process which produces wrought microstructure with microstructural gradients in grain size, grain orientation, dislocation density, and precipitate distribution. The type and degree of microstructural modification is a function of the particular alloy chosen, its initial temper, the tool design and corresponding weld process parameter window, and other variables like material thickness, size, fixturing, etc. Since the microstructural changes produced can dramatically affect resultant mechanical performance and corrosion response, a thorough understanding of the variables involved in those changes is needed. A design of experiments approach was used to study the effects of welding parameter selection on the microstructural changes wrought by FSW with two different sizes of the same FSW tool design. A combination of microhardness mapping and electrical conductivity testing was used to investigate potential differences. The importance of these factors and the means for characterizing them for developing standards and specifications are also discussed.

• Periodical: Materials Science Forum (Volumes 638-642)
• Pages: 1261-1266
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.638-642.1261
• Online since: January 2010
• Authors: Christian A. Widener, Dwight A. Burford, Sarah Jurak
• Keywords: Aluminium Alloy 2024, Aluminum (Al), Corrosion, Electrical Conductivity, Friction Stir Welding (FSW), Heat Treatment, Microhardness, Parametric Study, Post Weld Artificial Aging (PWAA)

References

[1] Starink, M.J., and Jialin, Y., A Model for Strengthening of Al-Cu-Mg Alloys by S Phase, Proceedings from the Materials Solutions Conference 2003: 1st International Symposium on Metallurgical Modeling for Aluminum Alloys, Pittsburgh, PA, 13-15 October, 2003, pp.119-126.

[2] Wang, S.C., Starink, M.J., and Gao, N., Precipitation Hardening in Al-Cu-Mg Alloys Revisited, Scripta Materialia, vol. 54, no. 2, January, 2006, pp.287-291.

DOI: 10.1016/j.scriptamat.2005.09.010

[3] Heat Treatment of Wrought Aluminum Alloy Parts, Aerospace Material Specification, AMS 2770G, April, (2003).

[4] Genevois, C., Deschamps, A., Denquin, A., and Doisneau-cottingnies, B., Quantitative Investigation of Precipitation and Mechanical Behaviour for AA2024 Friction Stir Welds, Acta Materialia, vol. 53, no. 8, May, 2005, pp.2447-2458.

DOI: 10.1016/j.actamat.2005.02.007

[5] Genevois, C., Deschamps, A., and Denquin, A., Characterization of the Microstructural Evolution During Friction Stir Welding of Aluminum Alloys: A Comparative Study of 5251 and 2024 Alloys, Proceedings of the 5 th International Friction Stir Welding Symposium, sponsored by TWI, Ltd., Metz, France 14-16 September, (2004).

DOI: 10.1201/9781315116815-3

[6] Widener, C.A.; Tweedy, B.M.; Burford, D.A. Path Independence of Allowables Based Friction Stir Butt Welds, 7th AIAA Aviation Technology, Integration, and Operations Conference, Belfast, Northern Ireland, September 18-20, (2007).

DOI: 10.2514/6.2007-7864

[7] Burford, D.A., Tweedy, B.M., and Widener, C.A. Influence of Shoulder Configuration and Geometric Features on FSW Track Properties, 6th International Symposium on Friction Stir Welding, Saint-Sauveur, Nr Montréal, Canada, October 10-13, (2006).

DOI: 10.1108/acmm.2005.12852dac.001

[8] Reynolds, A.P.; Tang, W.; Khandkar, Z.; Khan, J.A. and Lindner, K., Relationships between weld parameters, hardness distribution and temperature history in alloy 7050 friction stir welds, Science and Technology of Welding and Joining, vol. 10, no. 2, 2005, pp.190-199.

DOI: 10.1179/174329305x37024