Mathematical model of complex weld penetration profile: A case of square AC waveform arc welding

A new mathematical model of complex weld bead shape is presented. An 'offsetting bi-elliptical' model is constituted that can capture complex geometric features such as observed in square waveform welds vis-à-vis deeper central core and shallow sides with two visually distinct weld zones. The model elucidates new observations on electrode melting and weld bead formation in alternating current waveform submerged arc welding visualised through in-situ radiography imaging. The geometric attributes of constituent ellipses as function of welding process parameters are obtained with inverse modelling. The model yields high degree of accuracy in predication of bead parameters i.e. bead width, depth of penetration, bay angle and bay length for a wide range of process parameters such as EN ratio (% time an electrode remains negative) and wire-feed speed under different chemical composition of shielding flux. The investigation indicates that electrode melting and weld penetration are integrated outcomes of arc phenomena that is influenced by flux chemistry. The findings of present investigations are accomplished enough to be horizontally deployed to develop or improve existing weld bead models.