EFFECT OF TOOL TILT ANGLE ON MICROSTRUCTURAL CHARACTERISTICS OF FRICTION STIR WELDED LAP JOINTS OF AA2014-T6 ALUMINUM ALLOY JOINTS
Keywords:Aluminum alloy, Friction stir lap welding, Tool tilt angle, tensile properties
The high strength aluminum alloys such as 2xxx and 7xxx series are suitable for parts and structure requiring high strength to weight ratio and are commonly used in aircraft fuselage and wing skins. The structures are conventionally joined by rivets. It is difficult to join these aluminum alloys especially 2xxx series by fusion welding processes due to break up of oxide layer which usually result in solidification cracking, burn through and porosity. Hence to overcome such problems solid state welding technique is chosen. Friction stir welding (FSW) is one such promising process, which can be effectively applied to weld these alloys for aircraft application with lap joint configuration. In this present investigation, the aluminum alloys 2014 were lap welded by friction stir welding technology. Effect of tool tilt angle on tensile shear fracture load (TSFL) and microstructure properties were studied experimentally. In this present study, the tool tilt angle was varied from 0° to 4° with an interval of 1o while other parameters such as tool rotational speed, welding speed, tool shoulder diameter were kept constant. Tensile shear fracture load, macro and microstructure analysis were performed to evaluate the joint strength. This investigation revealed that defect free friction stir lap welding (FSLW) was achieved by while using tool tilt angle of 1°, 2 °and 3°. However, maximum TSFL of 14.42 kN was exhibited by the joint fabricated using a tool tilt angle of 3° and the results are discussed in detail.
Thomas W M, Nicholas E D, Needham J C, Murch M G, Temple smith P and Dawes C J (1992), “Improvements relating to friction welding”, European patent specification 0615480B1.
Nandan R, Debroy T and Bhadshia H K D H (2008), “Recent advances in friction stir welding-process, weldment structure and properties”, Progress in Material Science, Vol. 53,980-1023.
Mishra R M and Mahoney M W, “Friction stir welding and processing”, ASM International, pp. 360
Terry Khalid, An outsider looks at friction stir welding, ANM-112N-05-06 (2005).
Williams S W (2001), “Welding of airframes using friction stir”, Air & Space Europe, Vol. 3, 646-66.
Dawes C J (1995),“An introduction to friction stir welding and its development”, Welding and metal fabrication, Vol. 12.
Liu G, Murr L E, Niou C S, McClure J C and Vega F R (1997),”Micro structural aspects of the friction stir welding of 6061-T6 aluminium”, Scripta Materlia, Vol.37(3), 355-361.
Mishraa R S and Ma Z Y (2005), “Friction stir welding and processing”, Materials Science and Engineering: R: Reports, Vol. 50 (1-2),1-78.
Chen Z W and Cui S (2008), “On the firming mechanism of banded structures in aluminum alloy friction stir welds”, Scripta Materialia, Vol. 58, 417-420.
Kato K, Tikisu H and Ito G (2004), “Mechanical properties of friction stir welded 6061 aluminium alloy”, Welded international, Vol. 18, 95-102.
Barlas Z and Ozsarac U (2012),“Effect of FSW parameters on joint properties of AlMg3 alloy”, Welding Research, Vol. 91, 16s-22s.
Moneer H Tolephih, Hatem M Mahamood, Athra A H Hasheem and Esam T Abdullah (2013), “Effect of tool offset and tilt angle on weld strength of butt joint friction stir welded specimens of AA2024 aluminium alloy welded to commercial pure copper”, Chemistry and materials research, Vol.3 (4), 49-58.
Pande S V and Badhesha V J (2014), “Effect of tool pin offset on mechanical and metallurgical properties of dissimilar FSW joints of AA6061 T6 aluminum alloy and copper material”, In. procedings of International Welding Congress (IC2014), New Delhi, India,697-703.
Galvo I, Leal R M, Loureiro A and Rodrigues D M (2010), “Material flow in heterogeneous friction stir Welding of aluminum and copper thin sheets”, Science and technology of welding and joining, Vol. 15, 654-660.
Buffa G, Hua J, Sivapuri R, and Fratini L (2006),” A continuum based FEM model for friction stir welding – model development, Mate.Sci.Eng. A,Vol. 419,381.
Reshad Seighalani K, Besharati Givi M K, Nasiri A M and Bahemmat P (2010), “Investigations on the Effects of the Tool Material, Geometry, and Tilt Angle on Friction Stir Welding of Pure Titanium” Journal of material engineering and performance, Vol. 19(7), 955–962.
Krishnan K N (2002),“On the formation of onion rings in friction stir welds” Mate. Sci. Eng. A, Vol. 327(2), 246- 251.
Ýpekoðlu G, Kiral B G, Erim S and Çam G (2012), “Investigation of the effect of temper condition on friction stir weldability of AA7075 Alalloy plates”, Mater Technol Vol. 46, 627–632.
Hou J C, Liu H J and Zhao Y Q (2014), “Influences of rotation speed on microstructures and mechanical properties of 6061-T6 aluminum alloy joints fabricated by self-reacting friction stir welding tool”, Int J Adv Manuf Technol, Vol. 73, 1073–1079.
Babu S, Janakiram G D, Venkatakrishnan V, Madhusudhana reddy G and Prasad rao K,(2012),“Microstructure and mechanical properties of friction stir lap welded aluminum alloy AA2014” J.mate.Sci.tech, Vol. 28(5), 414-426.
Cedeqvist L, and Reynolds A.P (2001), “Factors affecting the properties of friction stir lap joints”, Weld. J.,Vol. 80,281s.
Rajendran C, Srinivasan K, Balasubramanian V, Balaji H, and Selvaraj P (2016), “Developing Empirical relationship to predict tensile strength of friction stir welded butt joints of AA2014-T6 aluminium alloy”, Journal of Manufacturing Engineering, Vol. 11(2) , 079-085.