1998 Volume 47 Issue 2 Pages 124-130
Effects of the composition of surface film on the corrosion resistance of bright annealed stainless steels were investigated. Bright annealing and immersing in nitric acid solution were carried out in order to make specimens having various surface film. The composition of the surface film was determined by SIMS (secondary ion mass spectrometry) and the corrosion resistance was examined by pitting potential measurements, crevice corrosion potential measurements, a ferroxyl test, an atmospheric exposure test at coastal-industrial sites and immersing test in sulfuric acid solution. It was found that the corrosion resistance was much influenced by the composition of the surface film of bright annealed stainless steel. Surface film having higher Si or Cr content, and lower Fe content which is made by the bright annealing in 75vol%H2-25vol%N2 atmosphere with lower dew point than -40°C accompanied by sufficiently long soaking is desirable for raising the pitting or crevice corrosion resistance of SUS304 and SUS430LX. Reduction of Fe content in the surface film by immersing in nitric acid solution also raised the corrosion resistance by the atmospheric exposure test and the ferroxyl test.
