Fatigue Crack Growth Behavior of FSWed Joint Joined with a Bobbin Type Tool in Different Aluminum Alloys

Abstract:

Fatigue crack growth (FCG) behavior at weld nugget zone (WNZ) and heat affected zone (HAZ) in friction stir welded (FSWed) joints joined by using a bobbin type tool in 5052, 6N01 and 7N01 aluminum alloys were investigated comparing to the base materials (BM). Constant stress amplitude fatigue crack growth tests were conducted with stress ratio of 0.1. Crack closure behavior was investigated simultaneously during fatigue test with unloading elastic compliance method. The results in this study showed that in near threshold region, FCG resistance in WNZ of FSWed 5052 and 6N01 joints was lower than that in the BM and the HAZ. In contrast, FCG resistance in WNZ of FSWed 7N01 joint was higher than that in the BM and the HAZ. At high ΔK region, WNZ of FSWed 5052 joint had the similar FCG resistance with the BM and the HAZ. However, WNZ of FSWed 6N01 joint showed lower FCG resistance compared to the BM and the HAZ. FCG resistance in WNZ of FSWed 7N01 joint was the similar with that in the HAZ but was lower than that in the BM. Crack closure behavior was observed in BM and HAZ for all materials tested. In WNZ, crack closure was found in FSWed 7N01 joint but was not found in FSWed 5052 and 6N01 joints. Difference in FCG behavior at different weld region was mainly due to difference in crack closure behavior in FSWed 5052 and 6N01 joints. However, in case of FSWed 7N01 joint, it is considered that effect of microstructure was significant on FCG behavior even at high ΔK region.

• Periodical: Applied Mechanics and Materials (Volumes 446-447)
• Pages: 32-39
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.446-447.32
• Online since: November 2013
• Authors: Panya Buahombura, Yukio Miyashita, Yuichi Otsuka, Yoshiharu Mutoh, Seo Nobushiro
• Keywords: Aluminium Alloy, Bobbin Type Tool, Crack Closure, Fatigue Crack Growth Behavior, Friction Stir Welding (FSW)

References

[1] R.S. Mishra and Z.Y. Ma, Friction stir welding and processing, Mat. Sci. Eng. R. 50 (2005) 1-78.

[2] L.E. Murr, A Review of FSW Research on Dissimilar Metal and Alloy Systems, J. Mat. Eng. Perform. 19 (2010) 1071-1089.

DOI: 10.1007/s11665-010-9598-0

[3] A.L. Biro, B.F. Chenelle and D.A. Lados, Processing, Microstructure, and Residual Stress Effects on Strength and Fatigue Crack Growth Properties in Friction Stir Welding: A Review, Met. Mat. Tran. B. 43B (2012) 1622-1636.

DOI: 10.1007/s11663-012-9716-5

[4] G. Bussu and P.E. Irving, The role of residual stress and heat affected zone properties on fatigue crack propagation in friction stir welded 2024-T351 aluminum joints, Int. J. Fat. 25 (2003) 77-88.

DOI: 10.1016/s0142-1123(02)00038-5

[5] K.V. Jata, K.K. Sankaran and J.J. Ruschau, Friction-Stir Welding Effects on Microstructure and Fatigue of Aluminum Alloy 7050-T7451, Met. Mat. Trans. A. 31A (2000) 2181-2192.

DOI: 10.1007/s11661-000-0136-9

[6] T.H. Tra, M. Okazaki and K. Suzuki, Fatigue crack propagation behavior in friction stir welding of AA6063-T5: Role of residual stress and microstructure, Int. J. Fat. 43 (2012) 23-29.

DOI: 10.1016/j.ijfatigue.2012.02.003

[7] S. Kim, C.G. Lee and S.J. Kim, Fatigue crack propagation behavior of friction stir welded 5083-H32 and 6061-T651 aluminum alloys, Mat. Sci. Eng. A. 478 (2008) 56-64.

DOI: 10.1016/j.msea.2007.06.008

[8] ASTM E 647-08, Annual Book of ASTM standards, (2008).

[9] G. Pouget and A.P. Reynolds, Residual stress and microstructure effects on fatigue crack growth in AA2050 friction stir welds, Int. J. Fat. 30 (2008) 463-472.

DOI: 10.1016/j.ijfatigue.2007.04.016

[10] L. Fratini, S. Pasta and A.P. Reynolds, Fatigue crack growth in 2024-T351 friction stir welded joints: Longitudinal residual stress and microstructure effects, Int. J. Fat. 31 (2009) 495-500.

DOI: 10.1016/j.ijfatigue.2008.05.004

[11] Y.E. Ma, P. Staron, T. Fischer and P.E. Irving, Size effects on residual stress and fatigue crack growth in friction stir welded 2195-T8 aluminum - Part I: Experiments Int. J. Fat. 33 (2011) 1417-1425.

DOI: 10.1016/j.ijfatigue.2011.05.006

[12] Y.E. Ma, Z.Q. Zhao, B.Q. Liu and W.Y. Li, Mechanical properties and fatigue crack growth rates in friction stir welded nugget of 2198-T8 Al-Li alloy joints, Mat. Sci. Eng. A. 569 (2013) 41-47.

DOI: 10.1016/j.msea.2013.01.044

[13] A.A. Korda, Y. Miyashita, Y. Mutoh and T. Sadasue, Fatigue crack growth behavior in ferritic-pearlitic steels with networked and distributed pearlite structures, Int. J. Fat. 29 (2007) 1140-1148.

DOI: 10.1016/j.ijfatigue.2006.09.008