Effect of transverse mechanical arc oscillation on hot cracking (solidification & liquation) and weld metal properties of AA2014 T6 TIG welds

Abstract

Effect of Transverse Mechanical Arc Oscillation on solidification and liquation cracking in autogenous and filler metals (standard AA4043 and non-standard AA1100 fillers) full penetration heat treatable AA2014 T6 aluminium alloy has been investigated. Both, linear and circular TIG welds were made using specially designed welding setup using Mechanical Arc Oscillation. Arc oscillation was carried out using range of oscillation parameters (amplitude: 0.9–2.0 mm and frequency: 0.28–1.5 Hz). Microstructure and mechanical tests studies were carried out to determine the extent of hot cracking, changes in the microstructure in weld fusion zone and adjacent, partially melted zone and weld mechanical properties respectively. Reduction/elimination of both solidification and liquation cracking due to arc Transverse Mechanical Arc Oscillation in autogenous and filler metal linear and circular TIG welds of AA2014 T6 alloy was significant. Optimum oscillation parameters: amplitude (0.9 mm) and frequency (0.48 Hz), significantly assisted to reduce/eliminate cracking in the fusion zone and adjacent partially melted zone. Interestingly, in these welds, fusion zone grain size was minimum, 12 μm as compared to 21.9 μm in without arc oscillation. Solidification cracking tendency had a non-monotonic dependence while liquation cracking showed monotonic dependence on the combination of arc oscillation parameters with AA1100 filler welds. AA4043 filler welds produced noticeable improvements in mechanical properties. Increments upto 16.6% in YS, 5.6% UTS, 34% ductility, and 17% joint efficiency.