Effects of laser-induced oxidation on the corrosion resistance of AISI 304 stainless steel

The paper presents an analysis of the impact of oxide layers, manufactured by means of laser radiation (with varying energy densities), on the resistance of AISI 304 stainless steel to corrosion. Corrosion resistance tests have been carried out in a weakly acidic environment (H2SO4, pH = 3.5) and a neutral environment (NaCl, pH = 7). The experiment was performed with the use of a laser system equipped with the Ytterbium Yb3+ fiber laser with a pulse duration of 230 ns. It has been shown that the thermal-oriented laser process significantly affects the course and nature of cathode-anode processes occurring on the surface of irradiated materials. Compared to the unstructured reference samples, there has been a significant increase in corrosion resistance of AISI 304 steel in the range of laser fluence between 50 and 70 J/cm2. The Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses of the chemical composition of the surface of the samples as well as the change of their morphology (microcracks of oxide layers) are closely correlated with the electrochemical measurements. Corrosion intensity has also been specified as a function of the energy density used for the laser marking of the samples.