Laser welding of steels: Relationship between laser power, penetration depth, welding speed and beam polarization

Abstract

Experimental data have been generated for the bead-on-plate keyhole welding of mild steel using the TEM∞ beam from a 1.5 kW CO2 laser and a range of material thicknesses from 0.64 to 2.6 mm. For each thickness, the maximum welding speed was measured for laser powers from 600 to 1500 W, using the criterion of full penetration along a 5 cm length. Analysis of the data has yielded a simple correlation between laser power (P,kW), penetration depth (d,cm) and welding speed (v,cm/s). An analytical expression of this relationship has been derived for speeds from 1 to 16 cm/s. Stainless steel samples yield similar results. This correlation is interpreted in terms of the minimum energy envelope or range for laser welding as proposed by other workers and also in terms of the Swift-Hook and Gick theory of laser welding. Data on the effect of polarization are also presented and discussed in terms of the present correlation. Above a critical welding speed the welding efficiency is enhanced when the polarization of the laser beam is aligned with the direction of welding.Experimental data have been generated for the bead-on-plate keyhole welding of mild steel using the TEM∞ beam from a 1.5 kW CO2 laser and a range of material thicknesses from 0.64 to 2.6 mm. For each thickness, the maximum welding speed was measured for laser powers from 600 to 1500 W, using the criterion of full penetration along a 5 cm length. Analysis of the data has yielded a simple correlation between laser power (P,kW), penetration depth (d,cm) and welding speed (v,cm/s). An analytical expression of this relationship has been derived for speeds from 1 to 16 cm/s. Stainless steel samples yield similar results. This correlation is interpreted in terms of the minimum energy envelope or range for laser welding as proposed by other workers and also in terms of the Swift-Hook and Gick theory of laser welding. Data on the effect of polarization are also presented and discussed in terms of the present correlation. Above a critical welding speed the welding efficiency is enhanced when the polarization of the...