TENSILE PROPERTIES OF COLD METAL TRANSFERRED ARC WELDED AA6061-T6 ALUMINIUM ALLOY JOINTS
Keywords:
Aluminium alloy, Gas metal arc welding, Cold metal transfer, Tensile properties, MicrohardnessAbstract
The wide usage of 6xxx series aluminium alloys in automobile sector is mainly because of the exceptionally good weldability characteristics and better corrosion resistance. Cold metal transfer (CMT)arc welding process is an advanced variant of gas metal arc welding (GMAW) that has potential features such as low heat input and arc stability with an innovative wire feed system. This process is widely employed in automobile sector due to its higher welding speed and capability to weld thin sheets without defects like spatter, distortion and burn through. This article reports the welding of thin aluminium sheets (AA6061-T6) by cold metal transfer arc welding technique and presents the transverse tensile properties of the welded joints. The features of the microstructure are characterized by optical microscopy. The fracture surfaces are being examined by scanning electron microscopy. Microhardness survey was done along the cross section of the welded joint. During the tensile test, the welded joint failed at 12 mm from the center of the weld. It is clear that fracture is caused by softening in HAZ region by the formation of β′or β precipitates which are softer and incoherent in nature. The hardness results signify that the low hardness region was found in the HAZ region which is called as softened zone, where the transformation of precipitates or coarsening of grains takes place.
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References
Polmear I, St John D, Nie J F and Qian M (2017) , Light alloys: "Metallurgy of Light metals" 5th edition, BOOK, Butterworth- Heinemann Publications.
Lei H Y, Li Y B and Carlson B E (2017), "Cold metal transfer spot welding of 1 mm thick AA6061-T6", J. Manuf. Process, Vol. 28, 209–219.
Pickin C G and Young K (2006), "Evaluation of cold metal transfer (CMT) process for welding aluminium alloy", Sci. Technol. Weld. Join, Vol. 11, 583–585.
Wang P, Hu S, Shen J and Liang Y (2017), "Characterization the contribution and limitation of the characteristic processing parameters in cold metal transfer deposition of an Al alloy", J. Mater. Process. Technol, Vol. 245, 122–133. doi:10.1016/j.jmatprotec.2017.02.019.
Elrefaey A (2015), "Effectiveness of cold metal transfer process for welding 7075 aluminium alloys", Sci. Technol. Weld. Join. Vol. 20, 280–285. doi:10.1179/1362171815Y.0000000017.
Shu F Y, Lü Y H, Liu Y X, Xu F J, Sun Z, He P and Xu B S (2014), "FEM modeling of softened base metal in narrow-gap joint by CMT+P MIX welding procedure", Trans. Nonferrous Met. Soc. China, Vol. 24, 1830–1835. doi:10.1016/S1003- 6326(14)63260-X.
Elrefaey A and Ross N G (2015), "Microstructure and mechanical properties of cold metal transfer welding similar and dissimilar aluminum alloys", Acta Metall. Sin. Vol. 28, 715–724.
Gungor B, Kaluc E, Taban E, SIK A Ş Ş (2014), "Mechanical and microstructural properties of robotic Cold Metal Transfer (CMT) welded 5083-H111 and 6082-T651 aluminum alloys", Mater. Des. Vol. 54, 207–211.
Feng J, Zhang H and He P (2009), "The CMT short-circuiting metal transfer process and its use in thin aluminium sheets welding", Mater. Des. Vol. 30, 1850–1852.
Zhang C, Li G, Gao M, Yan J, Zeng X Y (2013), "Microstructure and process characterization of laser-cold metal transfer hybrid welding of AA6061 aluminum alloy", Int. J. Adv. Manuf. Technol. Vol. 68, 1253–1260.
Pérez J S, Ambriz R R, López F F C, Vigueras D J (2016), "Recovery of Mechanical Properties of a 6061-T6 Aluminum Weld by Heat Treatment After Welding", Metall. Mater. Trans. A Phys. Metall. Mater. Sci. Vol. 47, 3412–3422.
Ambriz R R, Barrera G, García R and López V H (2009), "A comparative study of the mechanical properties of 6061-T6 GMA welds obtained by the indirect electric arc (IEA) and the modified indirect electric arc (MIEA)", Mater. Des. Vol. 30, 2446–2453.
Prasad Rao K, Ramanaiah N and Viswanathan N (2008), " Partially melted zone cracking in AA6061 welds", Mater. Des. Vol. 29, 179–186.
Lakshminarayanan A K, Balasubramanian V and Elangovan K (2009), "Effect of welding processes on tensile properties of AA6061 aluminium alloy joints", Int. J. Adv. Manuf. Technol.Vol. 40, 286–296.
Malin V (1995), "Study of Metallurgical Phenomena in the HAZ of 6061-T6 Aluminum Welded Joints", Weld. J, Vol 74(9). 305– 318.
Porter D A, Easterling K E and Sherif Y (2009), "Phase Transformations in Metals and Alloys",. BOOK, CRC Press.