Fracture Location Characterizations of Dissimilar Friction Stir Welds

This paper reports the tensile fracture location characterizations of dissimilar friction stir welds between 5754 aluminium alloy and C11000 copper. The welds were produced using three shoulder diameter tools; namely, 15, 18 and 25 mm by varying the process parameters. The rotational speeds considered were 600, 950 and 1200 rpm while the feed rates employed were 50, 150 and 300 mm/min to represent the low, medium and high settings respectively. The tensile fracture locations were evaluated using the optical microscope to identify the fracture locations and were characterized. It was observed that 70% of the tensile samples failed in the Thermo Mechanically Affected Zone (TMAZ) of copper at the weld joints. Further evaluation of the fracture surfaces of the pulled tensile samples revealed that welds with low Ultimate Tensile Strength either have defects or intermetallics present at their joint interfaces.

Authors:

• Esther T. Akinlabi
• Stephen A. Akinlabi

Keywords:

• fracture location
• friction stir welding
• intermetallics
• metallography

References:

[1] W. M. Thomas, E. D. Nicholas, J. C. Needham, M. G. Murch, P.
Templesmith and C. J. Dawes. "Improvements relating to Friction
Welding". International Patent Application, PCT/GB92/02203 (Patent)
December 1991.
[2] R. S. Mishra and Z. Y. Ma. "Friction stir welding and processing".
Materials Science and Engineering R. 2005; 50: pp1-78.
[3] P. L. Threadgill. "Terminology in friction stir welding". Science and
Technology of Welding and Joining. 2007; 12(4): p. 357- 360.
[4] A. P. Reynolds. " Friction stir welding of aluminium alloys". In: Totten
GE, MacKenzie DS (eds.) Handbook of Aluminium, Volume 2 Alloy
Production and Materials Manufacturing. New York, Marcel Dekker;
2003. pp. 579-700.
[5] S. Lim, S. Kim, C. Lee and S. Kim. "Tensile behaviour of friction stir
welded Al 6061-T651". Metallurgical and Materials Transactions A
2004; 35: pp. 2829-2835.
[6] S. Lim, S. Kim, C. Lee and S. Kim. "Tensile behaviour of friction stir
welded A356-T6/Al 60610T651 bi-alloy plate". Metallurgical and
Materials Transactions A. 2004; 35: pp. 2837-2843.
[7] L. Ceschini, I. Boromei, G. Minak, A. Morri and F. Tarterini. "Effect of
friction stir welding on microstructure, tensile and fatigue properties of
the AA7005/10% vol. %Al2O3P composite". Composites Science and
Technology 2007; 67: pp. 605-615.
[8] J. Ouyang, E. Yarrapareddy and R. Kovacevic. "Microstructural
evolution in the friction stir welded 6061 aluminium alloy (T6- temper
condition) to copper". Journal of Materials Processing technology
2006; 172: pp. 110-122.
[9] A. Abdollah - Zadeh, T. Saeid and B. Sazgari. "Microstructural and
mechanical properties of friction stir welded aluminium/copper lap
Joints". Journal of Alloys and Compounds 2008; 460: pp. 535-538.
[10] H. Liu, H. Fujii, M. Maeda and K. Nogi. "Tensile fracture location
characterizations of friction stir joints of different alloys". Journal of
Material Science Technology, 2004; 20: pp. 103-105.
[11] R. Nandan, T. DebRoy and H. K. D. H. Bhadeshia. "Recent advances in
friction stir welding- Process, weldment structure and properties".
Progress in Material Science 2008; 53: pp. 980-1023.