Fiber laser cutting of Ti6Al4V sheets for subsequent welding operations: Effect of cutting parameters on butt joints mechanical properties and strain behaviour

The effect of laser cutting parameters on the mechanical behavior of laser butt welded joints whose edges were obtained by laser cutting was investigated. The paper aims to demonstrate that new high power solid-state fiber lasers not only represent a valid and reliable alternative to the most established CO2 and Nd:YAG laser sources, but also allow to obtain cuts having edges well suited for subsequent direct laser welding. First Ti6Al4V 1 mm thick sheets having edges machined by milling were laser welded. Once the optimal welding condition was determined, the mechanical characterization of sheets cut by fiber laser and then laser welded was performed. Comparative strain analysis performed by a digital image correlation technique highlighted the effect of the gap between the sheets resulting from the different cut edge quality. Experimental results showed that the correct selection of laser cutting parameters allows to obtain butt joints characterised by mechanical properties comparable with the ones obtained by milling. Cutting edge quality in the optimal range of gap values allows to obtain the best mechanical performances of the joint.

► Critical gap exceeded with higher Rt on cut edges obtained for lower gas pressure. ► Comparative strain analysis performed by a digital image correlation technique. ► Milling cut edges with lower Rt influence weld bead plastic behaviour and limit strain. ► Fiber lasers cut edges suited for direct laser welding without further machining. ► Laser cutting/welding for Ti6Al4V material optimization and machining costs reduction.