Determination of the long-term intergranular corrosion rate of stainless steel in concentrated nitric acid

Corrosion issues in nuclear fuel reprocessing plants

“…the rate of this phenomenon based on morphological considerations has been modelled recently [11][12][13]102]. The first model [11][12][13] is based on the fact that intergranular corrosion progresses according to two constant dissolution vectors: the penetration rate of grain boundary V g and the dissolution rate of the intergranular groove sides and of the specimen surface V s .…”

“…The first model [11][12][13] is based on the fact that intergranular corrosion progresses according to two constant dissolution vectors: the penetration rate of grain boundary V g and the dissolution rate of the intergranular groove sides and of the specimen surface V s . Stable grooves are indeed formed because V g is higher than V s .…”

“…where a is the opening angle of the grooves. the long-term penetration depth of corrosion can then be simply determined by measurement of the a angle and of the dissolution rate in a single short-term experiment, largely before stable grain-dropping [11][12][13]. the other method [102] for the long-term rate estimation consists in pretreating the steel into a corrosive medium to initiate the required stable graindropping, then treating the steel in the studied medium within a relatively short time with measurement of the deepest penetration during that time in a random section, normally to the surface.…”

Kinetics of the oxidation of stainless steel in hot and concentrated nitric acid in the passive and transpassive domains

“…The progression of these grooves inside the steel can induces grain dropping. Some authors proposed that this IGC morphology results from the existence of two different dissolution rates: a dissolution rate at the surface of the grains V s and a dissolution rate at the grain boundaries V gb [10][11][12][13][14]. Based on this phenomenology, a model shows that the total mass loss of the steel is thus ascribable to two contributions: steel oxidation / dissolution and grain dropping [13].…”

“…In addition to metal oxidation, nitric acid reduction occurs in a large potential range that partially superimposes the anodic domain of SS [2,14]. The complex reduction phenomena of nitric acid have been widely studied and the reduction mechanisms on the surface of an inert electrode are now well established [15][16][17][18][19][20][21][22][23].…”