Intergranular oxidation of 316L stainless steel in the PWR primary water environment

After exposing AISI 316L stainless steel to the primary water environment across a range of temperatures (290 degrees C-360 degrees C) for 1000 h, the oxidation growth of the Cr-rich inner layer was measured: Samples exposed at 290 degrees C proved to have significantly greater oxide penetration than samples exposed at the higher temperatures. Furthermore, the annealed samples exhibit strong dependence of oxide growth on microtexture. The results suggest that an epitaxial relationship exists between the metal and the Cr-rich oxide, and that this relationship degrades above 290 degrees C as a result of differential thermal expansion between the oxide and the metal matrix.