Significant reduction of corrosion of stainless steel by strong-field laser surface passivation

Stainless steels are basic corrosion-resistant materials, but despite great efforts for over a century, they still suffer inevitably from environmental erosions by ubiquitous chemical reactions, resulting in typical corrosion rates at dozens of μm∙yr^-1. Here, we developed a strong-field laser passivation strategy to obtain super corrosion-resistant stainless steels through forming a hybrid µm-Fe₃O₄/Fe₂O₃/Cr₂O₃ passivation layer with unique bionic taro-leaf-like hierarchically heterogeneous Cassie-state micro/nanostructure morphologies. We observed up to 100,000-fold reduction in the corrosion rate of AISI 304 steel in saline, acidic as well as alkaline solutions. The ultralow corrosion rate can remain for >6500 hours. The generality was exemplified by exhibiting extreme anticorrosion enhancements of AISI 316, 420, 201, 430, and 2205 steels under the same conditions. This study reveals a new strategy for achieving super corrosion-resistant performance of stainless steels in various harsh environments.