In a series of systematic laboratory experiments, a pulsed 400 W Nd:YAG laser is compared with a 1150 W slow flow CO2 laser, operated pulsed at 400 W average power. The pulse capabilities of the two lasers are shown. Five types of materials are welded with the two lasers, AISI 304 stainless steel, AISI 316 stainless steel, SS2377 Dublex stainless steel, AlMgSi1 (DIN 1725) and pure copper (DIN SFCu).
For both laser types it is shown that a minimum pulse width exists at a fixed pulse energy that gives the deepest weld penetration while maintaining a sound weld. When the pulse energy is varied, a near linear correlation is found between the pulse energy and the optimum pulse width resulting in sound welds. The pulse energy/pulse width correlations for the two laser types are compared, and the differences between the obtained welds in the materials are discussed. The welds are quantified by the penetration depths, the weld surface conditions and the occurrence of undercut, pores and cracks in the material.