Improvement of corrosion resistance of stainless steel welded joint using a nanoporous oxide layer

Abstract

Due to the versatileness of stainless steel, it is widely used in various fields of industry. But, then, welding procedures are inevitable, and after those welding, corrosion resistance of stainless steel weld decreases with microstructural and mechanical changes. To solve such problems, research has been conducted by fabricating a nanoporous oxide layer on the stainless steel weld surface using a simple and eco-friend anodization method. Considering the anodization process which utilizes the ammonium fluoride containing electrolyte, corrosive fluoride species having solubility remains in the nanoporous oxide layer. To eliminate these fluoride species, heat treatment was conducted, and by doing so, a stable nanoporous oxide layer was fabricated mainly exhibiting the magnetite(Fe3O4) phase. After that, verification of improvement of corrosion resistance was done using electrochemical polarization technique and impedance spectroscopy, and following surface characterization investigated the integrity and protectiveness of the nanoporous oxide layer fabricated. The corresponding technique can be utilized through various fields which use stainless steel welding, increasing industrial stability.