Laser assisted cleaning of oxide films on SUS409 stainless steel

Laser assisted cleaning of oxide films on SUS409 stainless steel plates was studied both experimentally and theoretically. The highly oxidized surfaces with oxide scales of about 25 μm thickness were irradiated with Q-switched pulsed Nd:yttritium-aluminum-garnet lasers with and without frequency doubling, i.e., at 1064 and 532 nm wavelengths. Both multiple irradiation on single spots and scanning with pulsed lasers were employed. The variables studied were laser wavelength, pulse duration, number of pulses, and scanning velocity. The results indicate that heavily oxidized stainless steel surfaces can be cleaned with short, high power density pulses. Shorter laser wavelength, higher power density, and irradiation with multiple pulses improved surface cleaning. Stress wave induced spallation played an important role in the cleaning process. No loss of the underlying metal layer was observed during treatment.