Environmental resistance of oxide tags fabricated on 304L stainless steel via nanosecond pulsed laser irradiation

Nanosecond pulsed laser irradiation was used to fabricate colored, mechanically robust oxide “tags” on 304L stainless steel. Immersion in simulated seawater solution, salt fog exposure, and anodic polarization in a 3.5% NaCl solution were employed to evaluate the environmental resistance of these oxide tags. Single layer oxides outside a narrow thickness range (~100–150nm) are susceptible to dissolution in chloride containing environments. The 304L substrates immediately beneath the oxides corrode severely—attributed to Cr-depletion in the melt zone during laser processing. For the first time, multilayered oxides were fabricated with pulsed laser irradiation in an effort to expand the protective thickness range while also increasing the variety of film colors attainable in this range. Layered films grown using a laser scan rate of 475mm/s are more resistant to both localized and general corrosion than oxides fabricated at 550mm/s. In the absence of pre-processing to mitigate Cr-depletion, layered films can enhance environmental stability of the system. •Laser-stimulated oxidation of stainless steel•Fabrication of single layer coatings and multilayer coatings•Environmental resistance of single-layer and multilayer oxides•Correlation of environmental resistance with oxide thickness, structure, and morphology