Kerf formation mechanism and process control in thick carbon steel plates using laser remote cutting

The dismantling of complex, thick-walled steel structures in nuclear reactors and ship hulls poses significant challenges for traditional mechanical and conventional laser cutting methods due to issues such as tool wear and spatial constraints. This study proposed a novel noncontact dismantling method using laser remote cutting technology. An experimental study was conducted using a 12 kW laser to cut 10–50 mm thick carbon steel plates at a 300 mm standoff distance. The kerf formation mechanism under remote conditions was examined with high-speed photography, while the effects of tilt orientation, assist gas pressure, and nozzle diameter on cutting performance were evaluated alongside a finite element simulation of the gas flow field. Results indicated that remote laser cutting generated a wider, tapered kerf compared to conventional cutting, with partial adhesion at the kerf end frequently preventing full separation. This adhesion was attributed to inherent difficulties in initiating the cut, coupled with the transverse flow of molten slag toward the kerf end. Optimization of the cutting head tilt angle enhanced initial penetration, suppressed lateral slag flow, and increased the maximum cutting speed for all thicknesses tested. For 50 mm thick plates, the maximum cutting speed increased from 60 mm/min at 0° tilt to 78 mm/min at −5° tilt, representing a 30% improvement. Concurrently, selecting appropriate assist gas pressure (14 bar) and nozzle diameter (3.5 mm) concentrated the gas flow, increasing its velocity in the kerf to improve slag removal, which, in turn, enhanced both cutting speed and kerf width. This study provides procedural support and technical guidance for the practical application of remote laser dismantling in nuclear reactors and ship hull structures.