Identification of modes of welding using parametric studies during ytterbium fiber laser welding

Abstract

Abstract Titanium-based Ti6Al4V alloy and SS 316L are most widely used materials in the manufacturing industry. Also, recent developments in fiber lasers offer remarkable benefits for welding of titanium and stainless steel alloys on account of high processing ability and accuracy. Moreover, identification of conduction and keyhole mode welding during fiber laser welding process is a promising task. Therefore, aim of the present work is identification of weld limits viz, conduction, transition and keyhole in Ti6Al4V alloy and SS 316L welds with respect to fundamental dimensional and non-dimensional parameters. Also, the influence of laser welding process variables and thermal physical properties of Ti6Al4V alloy and SS 316L welds are investigated using linear energy, laser interaction energy and absorbed heat flux. Moreover, the effect of non-dimensional numbers viz. melting efficiency, non-dimensional heat input index, non-dimensional linear energy, Marangoni number and Fourier number are examined. The non-dimensional numbers correlated the combined effect of laser welding process variables and alloy properties with thermal and fluid flow characteristics to analyze its impact on weld pool development. And, evaluation of weld characteristics in definitive weld regimes relative to dimensional and non-dimensional numbers. Moreover, macro and micro-structural analysis and micro-hardness estimation is carried out at distinct weld regimes to examine the weld behaviour.