The United States Steel Research and Technology Center and International Steel Group Research worked jointly with the Caterpillar Technical Center to gain a better understanding of the effect of steel composition on the laser-cutting behavior of steel plates. In an effort to determine the effect of thermo-physical properties of steel such as liquidus temperature, exothermic reactivity, and thermal conductivity on high-power laser cuttability, laser cutting was carried out on plates rolled from several laboratory-melted heats containing varying levels of C, Si, Cu, Ni, Cr, and Mo. These plates were hot-rolled to 32 mm and blanchard-ground to 25 mm to eliminate the effects of surface scale and roughness variability.

No direct correlation was obtained among steel composition, laser cut quality and thermal conductivity in the cutting trials. However, examination of the cut surfaces using confocal microscopy indicated that the cutting front in steels containing residual elements was enriched with elements that did not oxidize during the cutting operation. This observation suggests that exothermic reactivity and changes to the local liquidus temperature of the steel at the cutting front resulting from the alloy enrichment may play a major role in the laser cutting process.