Effect of steel composition on the laser cutting behavior of 25-mm-thick plates

Attempts were made to gain a better understanding of the effects of steel composition and thermophysical properties, such as solidus and liquidus temperatures, heat of oxidation, surface tension, viscosity and thermal conductivity, on laser-cutting behavior. Laboratory-produced heats containing varying levels of C, S, Si, Cu, Ni, Cr, and Mo were hot-rolled to 32-mm-thick plates. Laser cutting was carried out after the plates were blanchard-ground to 25 mm and shot-blasted to eliminate surface effects and roughness variability. Under these conditions, Cu and Ni were found to improve cutting performance, while Cr degraded cutting performance. C and Si were not found to affect cut quality. No direct correlation was obtained among steel composition, laser cut quality, and thermophysical properties. However, limited confocal microscopy and energy dispersive x-ray spectroscopic analysis of selected cut surfaces suggested that enrichment at the cutting front of alloying elements resistant to oxidation might play a major role in determining cut quality.