Study of titanium sheets HPDL welding phenomenon

Abstract

Butt joints of titanium alloy Ti6Al4V (AMS 4928Q) thin sheets 1.0 and 1.5 mm thick were continuous-wave High Power Diode Laser (HPDL) laser welded. During course of experiments HPDL ROFIN SINAR DL 020 laser of maximum output power 2.3 kW and a rectangular laser beam spot of 1.8x6.8 mm at focusing distance 82 mm, and 1.8x3.8 mm at 30 mm was used. To provide precise positioning of the laser beam to weld joint and welding track, CNC positioning system was used. The heat input of surfacing was controlled by proper combination of the following parameters: laser beam spot size, beam spot position, laser power and welding speed. Bead on plate welds were produced, to avoid the influence of the sheet edges preparation, the joint fit-up, the welding gap and the laser beam alignment with the welding gap on the welding process. Special clamping device to provide total gas protection of weld root side was used and also special shape trailing shield was used to protect face area of the weld. The commercial grade argon and helium were used as shielding gases. Metallographic examinations and static and dynamic images of the weld pool have proved that the laser welding parameters have very strong influence on the shape of the weld pool, penetration depth, shape of the fusion zone and weld width.Butt joints of titanium alloy Ti6Al4V (AMS 4928Q) thin sheets 1.0 and 1.5 mm thick were continuous-wave High Power Diode Laser (HPDL) laser welded. During course of experiments HPDL ROFIN SINAR DL 020 laser of maximum output power 2.3 kW and a rectangular laser beam spot of 1.8x6.8 mm at focusing distance 82 mm, and 1.8x3.8 mm at 30 mm was used. To provide precise positioning of the laser beam to weld joint and welding track, CNC positioning system was used. The heat input of surfacing was controlled by proper combination of the following parameters: laser beam spot size, beam spot position, laser power and welding speed. Bead on plate welds were produced, to avoid the influence of the sheet edges preparation, the joint fit-up, the welding gap and the laser beam alignment with the welding gap on the welding process. Special clamping device to provide total gas protection of weld root side was used and also special shape trailing shield was used to protect face area of the weld. The commercial grade argon ...