Optimizing the corrosion resistance of AISI 316 L stainless steel by nano-second laser surface irradiation using humidity environment via the Taguchi method

The effect of laser treatment on the corrosion resistance of AISI 316 L stainless steel was investigated using the Taguchi method with an orthogonal array L 16 (4 4 ) of four variables, such as pulse overlap, power, relative humidity, and pulse duration. Range analysis determined the relative humidity (RH) as the most influential parameter, followed by power, pulse overlap, and pulse duration. The optimized parameters are 100 W laser power, 70% pulse overlap, 60 ns pulse width, and 80% relative humidity, at which a pitting potential of 1.4 V vs. Ag/AgCl in 3.5% NaCl solution was achieved after treatment. Further electrochemical tests, including Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (MS) analysis, demonstrated enhanced corrosion resistance of the optimized sample. Multi-technique characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) confirmed no changes in phase, surface remelting, and grain refinement, respectively. However, post-polarization Optical microscope (OM) surface analysis corresponded to fewer and smaller pits in the optimized sample compared to sample 2 and the untreated sample. Taken together, the current study gives key findings into optimizing laser processing parameters to increase the resistance to corrosion of stainless steels, offers a critical understanding, and provides techniques for improving the metal’s surface corrosion resistance.