This paper describes the idea of using a similar vacuum necessary for electron beam welding also for welding with a solid-state laser. While for electron beam welding a fine vacuum is required for the process, with laser beam welding the pressure can be varied as an additional process parameter in order to influence the process result. Test results show that by a reduction of the ambient pressure the metal vapor plume is suppressed and consequently the spattering decreases. Plume and spatters disappear completely at a pressure reduction to p = 10 hPa and below. This enables quality of weldings with the solid-state laser which even with CO₂ lasers are only difficult to realize. The quality of these weld seams is comparable to electron beam weldings. In addition, further beneficial properties arise in the quality of the weld seam. With the same process parameters but reduced ambient pressure, the reduction of the pressure effects an increase of the penetration depth and a distinctive modification of the seam geometry. Mild steel plates with a thickness of 10 mm have been successfully welded with a laser power of P_L = 6000 W and a feed rate of v_W = 2.0 m/min, with a remarkable seam quality without any irregularities. Another advantage of welding with the laser at reduced pressure is the possibility of avoiding a sagging of the seam during welding of thick sheets. Despite excessive energy and power, no geometric irregularities are identified in the cross section. Under atmospheric pressure, the high excess of power would lead to an intense seam collapse. On sheets with thicknesses of 3 mm, the notches occurring by penetration welding can also be avoided by applying reduced pressure.

Date Published: 22 February 2013
PDF: 13 pages
Proc. SPIE 8603, High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications II, 86030M (22 February 2013); doi: 10.1117/12.2003858

Published in SPIE Proceedings Vol. 8603:
High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications II
Friedhelm Dorsch, Editor(s)