Interaction time effects on the transition between conduction and keyhole laser welding

Abstract

Welding with a laser in keyhole mode provides deep penetration and/or high process speeds. On the other hand welding in the conduction provides much higher quality with no defects or spatter. When welding in conduction mode it is essentially to avoid keyhole effect in order to maintain this quality. We have studied the transition between conduction and keyhole modes by varying the laser intensity and the interaction time, which is defined as the laser beam diameter divided by the travel speed. The results show that there is not one unique intensity value where the transition between keyhole and conduction mode occurs. Rather there is a range of values dependant on the interaction time. In practice this means that for a given laser spot size there are combinations of laser power and travel speed that can be indentified where keyhole effects can be avoided. The transition study was also extended to pulsed laser, where interaction time is defined as the pulse duration.Welding with a laser in keyhole mode provides deep penetration and/or high process speeds. On the other hand welding in the conduction provides much higher quality with no defects or spatter. When welding in conduction mode it is essentially to avoid keyhole effect in order to maintain this quality. We have studied the transition between conduction and keyhole modes by varying the laser intensity and the interaction time, which is defined as the laser beam diameter divided by the travel speed. The results show that there is not one unique intensity value where the transition between keyhole and conduction mode occurs. Rather there is a range of values dependant on the interaction time. In practice this means that for a given laser spot size there are combinations of laser power and travel speed that can be indentified where keyhole effects can be avoided. The transition study was also extended to pulsed laser, where interaction time is defined as the pulse duration.