Metal processing with a high-power CO2laser

Experimental studies involving laser welding, cutting, and surface heat treating have been performed over the past two years at power levels of 4-16 kW, using an electron-beam stabilized CW Co2laser [1], [2]. Deep penetration welds have been made in a variety of materials including carbon and stainless steels, titanium, and aluminum. In all cases, normalized welding speeds and penetrations were in good agreement with electron-beam welding data. Actual values of material penetration in 304 stainless steel were within 70 percent of those achieved under the same conditions with hard vacuum electron beams between 50-200 in/min. A limited amount of testing has been conducted on laser cutting. For most of the tests, an inert gas jet was used to clear the kerr material and shield the cut edges. Band-saw quality edges were obtained in materials such as Inconel 718. Edges were sufficiently free of oxide formations and irregularities to allow rewelding of the pieces with the resulting weld quality equal to that for the machined edge samples of the same material. For heat-treating applications, the laser beam was defocused to spot sizes variable from 3/8 to 1 in, and the resulting beam has been swept over the surface of heat-treatable iron and steel coated with an appropriate absorptive material. With this setup, hardening case depths of 0.005-0.05 in have been achieved with very little part distortion and surface upset; Hardness in excess of Rc60 has been achieved. Hardening coverage rates of 100 in²/min have been achieved.