Surface modification of stainless steel by laser-induced wet treatment in aluminum nitrate solution

A laser-induced wet treatment was conducted on the stainless steel (SUS316L) surfaces. The disk-shaped samples were soaked in an aluminum nitrate solution and subsequently irradiated by a Yb fiber pulsed laser beam. The treated surfaces were observed with a scanning electron microscope, and analyzed with an energy dispersive X-ray spectrometer and X-ray diffraction. It was confirmed that the proposed treatment generated an Al- and O-rich layer, which was identified as Fe²⁺Al₂O₄ structure. The thickness of the generated layer increased with increasing the Al concentration of solution, increasing laser power and decreasing laser scan rate.