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, Microhardness
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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