Abstract
Although it is generally assumed that friction stir seam welds and friction stir spot welds are free of many of the defect formation issues commonly associated with fusion welding, liquid penetration induced (LPI) cracking in the stir zone have been recently found in friction stir spot welds of AZ91. In the present study, cracking during friction stir spot welding of Mg-alloy (AZ91, AM60 and AZ31) sections is examined. Both liquation cracking and liquid penetration induced (LPI) cracking are observed in Mg-alloy friction stir welded joints. Local melting and cracking is also apparent in Al 7075-T6 friction stir spot welds produced with the precise objective of limiting dissolution of melted eutectic films in the high temperature stir zone and when spot welds cool to room temperature. Based on these test results there is no need to assume that the stir zone temperature during friction stir spot welding is less than that required for formation of melted eutectic films or for spontaneous melting of second-phase particles contained in the as-received base material.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
ASM Specialty Handbook, Magnesium and Magnesium Alloys, ASM International, 1999, pp. 106–118.
Lathabai S., Barton K.J., Harris D., Lloyd P.G., Viano D.M., McLean A.: Welding and weldability of AZ31B by gas tungsten arc and laser beam welding processes, Magnesium Technology 2003, TMS, 2003, pp. 157–162.
Stern A., Munitz A., Kohn G.: Application of welding technologies for joining of Mg alloys: Microstructure and mechanical properties, Magnesium Technology 2003, TMS, 2003, pp. 163–167.
Tanaka M.: Report of study group for high efficiency welding processes of thin sheet plate, J. Japan Welding Soc., 2004, 74–5, 358.
Gerlich A., Avramovic-Cingara G., North T.H.: Stir zone microstructure and strain rate during Al 7075-T6 Friction Stir Spot Welding, Met. Trans. A., 2006, Vol. 37A, pp. 2773–2786.
Gerlich A., Su P., Yamamoto M., North T.H.: Effect of welding parameters on the strain rate and microstructure of friction stir spot welded 2024 aluminum alloy, J. Mat. Sci., 2007, on-line.
Gerlich A., Su P., North T.H.: Friction stir spot welding of Mg-alloys for automotive applications, in “Magnesium Technology 2005”, 2005, eds. N. R. Neelameggham, H. I. Kaplan and B. R. Powell, TMS, pp. 383–388.
Yamamoto M., Gerlich A., North T.H., Shinozaki K.: Cracking in the stir zones of Mg-alloy friction stir spot welds, J. Mat. Sci., 2007, 42, 18, pp. 7657–7666.
Gerlich A., Su P., North T.H.: Peak temperatures and microstructures in aluminium and magnesium alloy friction stir spot welds, Sci. Tech. Weld. Joining, 2005, 10, 6, pp. 647–652.
Gerlich A., Su P., North T.H.: Tool penetration during friction stir spot welding of Al and Mg alloys, J. Mat. Sci., 2005, 40, pp. 6473–6481.
Gerlich A., Su P., North T.H., Bendzsak G.J.: Friction stir spot welding of aluminum and magnesium alloys, Materials Forum, 2005, 29, pp. 290–294.
Su P., Gerlich A., North T.H., Bendzsak G.J.: Energy utilisation and generation during friction stir spot welding, Sci. Tech. Weld. Joining, 2006, 11, 2, pp. 163–169.
Su P., Gerlich A., North T.H., Bendzsak G.J.: Energy generation and stir zone dimensions in friction stir spot welds, SAE Technical Series, 2006-01–0971.
Gerlich A., Yamamoto M., North T.H.: Strain rates and grain growth in 5754 and 6061 friction stir spot welds, Met. Trans. A, 2007, in press.
Gerlich A., Yamamoto M., North T.H.: Local melting and tool slippage during friction stir spot welding of Al-alloys, J. Mat. Sci., Special Edition on Joining Science and Technology, 2007, in press.
Yamamoto M., Gerlich A., North T.H., Shinozaki K.: Mechanism of cracking in AZ91 friction stir spot welds, Sci. Tech. Weld. Joining, 2007, 12, 3, pp. 208–216.
Yamamoto M., Su P., Gerlich A., North T.H., Shinozaki K.: Liquid Penetration Induced (LPI) cracking in AZ91 friction stir spot welds, J. Jpn. Welding Soc., 2007, 25, 1, pp. 208–214 (in Japanese).
Yamamoto M., Su P., Gerlich A., North T.H., Shinozaki K.: Eutectic segregation and cracking in AZ91 friction stir spot welds, SAE Technical Series, 2007, 2007-01–1700.
Su P., Gerlich A., North T.H., Bendzsak G.J.: Intermixing in dissimilar friction stir spot welds, Met. Trans. A, 2007, on-line.
Shinozaki K., North T.H., Yamamoto M., Gerlich A., Horie S., Soejima H., Kamiyama H.: Cracking in dissimilar friction stir spot welding of Mg-Alloy AM60/AZ91, Preprints of the National Meeting of Japan Welding Soc., 2007, Vol. 2007f, pp. 75–76 (in Japanese).
Yamamoto M., Gerlich A., North T.H.: Cracking in dissimilar Mg-alloy friction stir spot welds, Science and Technology of Welding and Joining, 2007, To be published.
Reiso O., Øverlie H.-G., Ryum N.: Dissolution and melting of secondary Al2Cu phase particles in an AlCu Alloy, Met. Trans., 1990, vol. 21A, 1689.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yamamoto, M., Gerlich, A., North, T.H. et al. Cracking and Local Melting in Mg-Alloy and Al-Alloy During Friction Stir Spot Welding. Weld World 52, 38–46 (2008). https://doi.org/10.1007/BF03266667
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03266667