Monitoring and local gas shielding at laser-based welding of titanium alloys

Abstract

Insufficiently shielded joints during laser-based welding of titanium alloys become brittle and result in not loadable connections, which leads to the necessity of gas shielding. Typically, such welding procedures are performed in a shielding gas chamber, which makes the process complex and leads to high gas consumption and gas purging time. To overcome this, a locally acting shielding gas bell was developed, which allows direction-independent laser welding on flat components with an oxygen concentration of less than 20 ppm. Further, the bell extracts fume and continues to cover the material with shielding gas during material cooling. To automate path teaching in welding operations, an optical-based sensor system was developed and integrated into the optical path of the laser. External lighting was integrated into the gas shield bell to improve joint recognition and monitoring. The novel shield gas bell and monitoring system are validated using Ti-6Al-4V welds.