Corrosion Behavior of Stainless Steels in Simulated PWR Primary Water —Effect of Chromium Content in Alloys and Dissolved Hydrogen—

Abstract

The structure and composition of surface oxide films on austenitic stainless steels in hydrogenated high-temperature water were examined by changing the chromium content in alloys and the concentration of dissolved hydrogen in high-temperature water. Auger electron spectroscopy, X-ray diffraction and analytical transmission electron microscopy revealed that the oxide films had a double-layer structure: ironbased spinels as the outer layer and chromium-rich spinel oxide as the inner layer. Increasing the chromium content suppressed the corrosion rate and produced fine oxide particles with a higher chromium concentration in the inner layer. Increasing the concentration of dissolved hydrogen enhanced the corrosion rate without a notable change in oxide structure. These influences are considered to originate from changes in cation diffusion through the inner layer, such as a decrease in the lattice diffusion of iron in the inner layer due to a higher concentration of chromium in the oxide as a diffusion barrier for a high chromium content in the alloys and due to a lower oxygen partial pressure for a higher concentration of dissolved hydrogen.

Combined effect of gamma-radiation and pH on corrosion of Ni–Cr–Fe alloy inconel 600

“…The relative intensities of the Ni-2p, Cr-2p and Fe-2p peaks in the XPS survey spectra obtained at different pHs and radiation environments are shown in Fig. 5 [4][5][6][7][8]32,33,[48][49][50][51][52][53][54][55]. At pH 10.6 the enrichment ratio for Cr is lower and that for Fe is higher in the presence of radiation compared to those in the absence of radiation.…”

Effect of pH on corrosion behavior of 316L stainless steel in hydrogenated high temperature water

“…The FT diffractogram in Figure b suggests that the oxide films formed in 5# solution consists of amorphous oxides. It is rather interesting that the structure of the oxide films formed in 5# solution is significantly different from that formed in 1# solution and published works …”

“…Figure shows the cross‐sectional STEM image and the elemental maps of the oxide films formed on 316L SS in 1# solution. It is well known that SSs have a double‐layer oxide film in high temperature water . However, the oxide films formed on 316L SS in 1# solution have a triple‐layer structure which is rather interesting.…”

“…Dissolution of oxides in high temperature water is also an important electrochemical factor affecting the corrosion rates of materials . Figure shows the evolution of solubility of Fe 3 O 4 , Cr 2 O 3 , and NiO in high temperature water with different pH at 300 °C .…”

Crack growth behavior of warm-rolled 316L austenitic stainless steel in high-temperature hydrogenated water

“…Based on the results of this study and the previous study [33], which evaluated the effect of DH concentration on the corrosion resistance of stainless steel, the increases in the inner oxide layer and crack growth rate can be explained. Firstly, with the increase in dissolved hydrogen, cathodic process can be promoted and result in a higher critical and passive current.…”