Analysis of the kerf quality in the fiber laser cutting of Ti6Al4V thin sheet

The high strength to weight ratio and good corrosion resistance of titanium alloys, have led to an increasing use of these materials, particularly in the aerospace industry. The laser cutting technique, may be a promising tool in machining titanium alloy parts like those with subsequent welding requirement: in this case, surface quality of the kerf edges is of great importance. The low thermal conductivity and the high chemical activity of titanium alloys lead, in fact, to alterations of the surface properties of the machined zone. This paper presents the results of titanium alloy laser cutting using a 2 kW fiber laser. The cutting process was performed in continuous wave mode and using Argon as shear gas. Laser cuts were realized on titanium alloy Ti6Al4V sheets 1mm thick. Image analysis and microscopy, were carried out to examine the cutting edge and alteration in microstructure. The paper investigates, with Design Of Experiment (DOE) techniques, the influences of cutting speed and shear gas pressure on some cutting edge quality features, including thickness of the heat-affected zone and those parameters which define the surface morphology and the micro-geometry of the machined zone.