The influence of the tool dimensions and of the welding parameters on the fracture and lap shear properties of friction stir spot welds is investigated. Interrupted lap shear tests allow to follow the mechanisms leading to weld fracture. A triangular cavity opens at the hook during lap shear testing. The distance between this triangular cavity and the hole left by the pin is the main parameter controlling the type of fracture. A too short distance favors a fracture through the weld nugget and hence should be avoided. In particular, this happens when the tool pin diameter is too small and when the plunge rate is too large. Fracture initiating at the triangular cavity and following the thermomechanically affected zone, i.e., by the pullout of the weld nugget, is preferred. This fracture type leads to significant plastic deformation and generally favors a large ultimate force during lap shear testing. Large ultimate forces are observed when the welds are cooler (large plunge rates and low rotation speeds), but the welding conditions should be chosen so as not to lead to fracture trough the weld nugget.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Thomas WM, Nicholas ED, Needham JC, Murch MG, Templesmith P, Dawes CJ (1991) Friction stir butt welding. GB Patent application n. 9125978-8
Threadgill PL, Leonard AJ, Shercliff HR, Withers PJ (2009) Friction stir welding of aluminium alloys. Int Mater Rev 54(2):49–93
Mishra RS, Ma ZY (2005) Friction stir welding and processing. Mater Sci Eng 50:1–78
Wang D-A, Lee S-C (2007) Microstructures and failure mechanisms of friction stir spot welds of aluminum 6061-T6 sheets. J Mater Process Technol 186(1–3):291–297
Gean A, Westgate SA, Kucza JC, Ehrstrom JC (1999) Static and fatigue behavior of spot-welded 5182-O aluminum alloy sheet. Weld J 78:80s–86s
Matsumoto K, Sasabe S (2001) Lap joints of aluminium alloys by friction stir welding. In: Proc. 3rd int. symp. FSW, Kobe, Japan
Badarinarayan H, Shi Y, Li X, Okamoto K (2009) Effect of tool geometry on hook formation and static strength of friction stir spot welded aluminum 5754-O sheets. Int J Mach Tools Manuf 49(11):814–823
Badarinarayan H, Yang Q, Zhu S (2009) Effect of tool geometry on static strength of friction stir spot-welded aluminum alloy. Int J Mach Tools Manu 49(2):142–148
Merzoug M, Mazari M, Berrahal L, Imad A (2010) Parametric studies of the process of friction spot stir welding of aluminium 6060-T5 alloys. Mater Des 31(6):3023–3028
Tozaki Y, Uematsu Y, Tokaji K (2007) Effect of processing parameters on static strength of dissimilar friction stir spot welds between different aluminium alloys. Fatigue Fract Eng M 30(2):143–148
Yin YH, Sun N, North TH, Hu SS (2010) Hook formation and mechanical properties in AZ31 friction stir spot welds. J Mater Process Technol 210(14):2062–2070
Bozzi S, Helbert-Etter AL, Baudin T, Klosek V, Kerbiguet JG, Criquid B (2010) Influence of FSSW parameters on fracture mechanisms of 5182 aluminium welds. J Mater Process Technol 210(11):1429–1435
Yin YH, Sun N, North TH Hu SS (2010) Influence of tool design on mechanical properties of AZ31 friction stir spot welds. Sci Technol Weld Join 15(1):81–86
Hirasawa S, Badarinarayan H, Okamoto K, Tomimura T, Kawanami T (2010) Analysis of effect of tool geometry on plastic flow during friction stir spot welding using particle method. J Mater Process Technol 210(11):1455–1463
Tran V-X, Pan J, Pan T (2009) Effects of processing time on strengths and failure modes of dissimilar spot friction welds between aluminum 5754-O and 7075-T6 sheets. J Mater Process Technol 209(8):3724–3739
Fujimoto M, Watanabe D, Abe N, Sato Y, Kokawa H (2010) Effects of process time and thread on tensile shear strength of al alloy lap joint produced by friction stir spot welding. Welding Int 24(3):169–175
Arul S, Miller S, Kruger G, Pan T, Mallick P, Shih A (2008) Experimental study of joint performance in spot friction welding of 6111-T4 aluminium alloy. Sci Technol Weld Join 13(7):629–637
Pan T, Joaquin A, Wilkosz DE, Feng Z, Santella ML (2004) Spot friction welding for sheet aluminum joining. In: Proc. 5th int. symp. FSW, Metz, France
Wang DA, Chao C-W, Lin P-C, Uan J-Y (2010) Mechanical characterization of friction stir spot microwelds. J Mater Process Technol 210(14):1942–1948
Lin P-C, Pan J, Pan T (2008) Failure modes and fatigue life estimations of spot friction welds in lap-shear specimens of aluminum 6111-T4 sheets. Part 2: welds made by a flat tool. Int J Fatigue 30(1):90–105
Mitlin D, Radmilovic V, Pan T, Chen J, Feng Z, Santalla ML (2006) Structure properties relations in spot friction welded 6111 aluminium. Mater Sci Eng A441:79–96
Su P, Gerlich A, North TH, Bendzsak GJ (2006) Material flow during friction stir spot welding. Sci Technol Weld Join 11(1):61–71
Gerlich A, Su P, Yamamoto M, North TH (2008) Material flow and intermixing during dissimilar friction stir welding. Sci Technol Weld Join 13(3):254–264
Simar A, Brechet Y, de Meester B, Denquin A, Pardoen T (2007) Sequential modeling of local precipitation, strength and strain hardening in friction stir welds of aluminium alloy 6005A-T6. Acta Mater 55:6133–6143
About this article
Cite this article
Jonckheere, C., de Meester, B., Cassiers, C. et al. Fracture and mechanical properties of friction stir spot welds in 6063-T6 aluminum alloy. Int J Adv Manuf Technol 62, 569–575 (2012). https://doi.org/10.1007/s00170-011-3795-3
- Friction stir spot welding
- 6063-T6 Aluminum alloy
- Hooking effect