Effect of repetition passes in the laser surface texturing of AISI 301LN steel on the anticorrosion properties in molten carbonate salts

Abstract

Laser Surface Texturing (LST) has recently emerged as a corrosion mitigation strategy for materials in contact with high-temperature molten salts used in the next-generation Concentrated Solar Power (CSP) technology. Some issues related to the LST parameters, which may affect the corrosion resistance, have not been addressed yet. Therefore, the present work is focused on the effect of laser input density and pass repetitions for improving the corrosion resistance in molten carbonate salts of AISI 301LN stainless steel. The textured surface produced by a nanosecond laser and the oxide scales formed during subsequent corrosion tests in a molten salt mixture of Li₂CO₃Na₂CO₃-K₂CO₃ at 600 °C were analysed by complementary analytical and microscopy techniques. The results showed that the treated-surface samples at high laser power presented a strong decrease in corrosion rate, as compared with the as-received sample. This is attributed to the formation of a thicker and denser protective oxide scale. However, high laser power increased the susceptibility to corrosion at the heat-affected zone (HAZ). It could be effectively prevented with the accumulation of laser repetition passes, offering a new potential approach to maximize the enhancement of corrosion resistance using LST in the design of components for next-generation CSP plants.