Early Pitting Detection of 304 Stainless Steel by Microscopic Chromogenic Method Combined with Three-Dimensional Video Microscopy Technique

Pitting corrosion behavior of 304 stainless steel with different surface roughness in 3.0%, 2.0%, 1.0%, 0.5% (mass fraction) NaCl solutions and pure water were in-situ and whole field monitored with microscopic chromogenic method. And the early pits in the stainless steel were analyzed using three-dimensional video microscopy technique. The results show that with the reduction of NaCl concentration in corrosion medium and surface roughness of stainless steel, the pitting induction time increased, and the pits decreased in number and distributed sparsely. Early pits in diameter of 3-6 μm can be detected by microscopic chromogenic method combined with three-dimensional video microscopy technique.