Investigation on Microstructure and Tensile Properties of High-Strength AA2014 Aluminium Alloy Welds Joined by Pulsed CMT Welding Process

Abstract

High-strength AA 2014 aluminium alloys are broadly employed for many applications because of their good mechanical properties, high strength-to-weight ratio, and better resistance to corrosion and are recyclable. The major problems in welding of AA 2014 aluminum alloy using a traditional joining process are partially melted zone, hot cracking, and alloy segregation. Cold metal transfer-welding (CMT) process is an advanced variant of gas metal arc welding process characterized by reduced heat input in which the welding wire is retracted during the short circuit which allows sufficient time for the weld to cool before placing each drop. In this investigation, the pulsed CMT welding process was chosen to weld high-strength AA2014 aluminium alloy under T6 condition. The joint tensile properties were compared with the parent material and correlated to the microstructural features. The defect-free weld was achieved at constant welding speed of 450 mm/min, welding current of 110 A, and electrode feed rate of 5550 mm/min. The joint weld using pulsed CMT yields a maximum strength of 303 MPa, extending joint efficiency up to 67%. It mainly refers to the beneficial effects of welding wire pulsing and dip and retreat motion which causes refining of dendritic grains in weld metal and enhances the strength of joints.