STABILIZATION OF PULSED GMAW IN TITANIUM WELDS WITH LOW-POWER LASERS

摘要

Fabricated titanium structures are of great interest for aircraft and military applications. However, in the pulsed gas metal arc welding (GMAW-P) of Ti it is difficult to achieve an acceptable weld due to the wandering around of the molten pool by cathode spot. The results of the "wandering" is an unstable metal transfer, spatter generation, and irregular weld bead shape. These results are more common in thinner Ti materials (<1 mm). As an alternative to GMAW-P, gas tungsten arc welding (GTAW) is most often used. However, GTAW in thinner materials is done at much slower speeds and therefore higher heat inputs. Because of the higher heat input the parts are more likely to be distorted. An alternative to GMAW-P or GTAW of Ti alloys is the use of lasers. Autogenous laser and hybrid welding (laser with GTAW, GMAW, or PTAW) have the potential of being used with Ti alloys. These welding processes have less heat input than GTAW or GMAWP and therefore less distortion. However, the cost of a high-power laser (>1 kW) may make fabrication cost too expensive to use in production. EWI has recently investigated hybrid welding of Ti alloys but using very low laser powers. The objective of this is to stabilize the GMAW-P process to achieve a high quality weld using a low-power laser (<500 W). Being able to use a low-power laser to achieve dramatic improvements in the GMAW-P welds could result in a wider use of fabricated structures. This low-power laser-hybrid approach could be used to fabricate structures as an alternative casting or other welding processes. This could impact aerospace, petrochemical, medical, and defense manufacturers where lower manufacturing cost are of interest.