These elements, particularly Mo, can significantly enhance the enrichment of Cr in the oxide and thus heals or repassivates the pit.
Reduction reaction occurs on the cathode.
In Impressed Current Cathodic Protection, the reaction on the anode depends on the nature of the anode material. For inert anode such as Platinised, Titanium Oxide anode, oxidation of the chemical species in the environment occurs. For consumable anode, oxidation of the anode material itself constitutes the anodic reaction. Yes, SCC is under constant load and CF is under cyclic load. This difference further leads to many other different characteristics of the two forms of failure e.g. transgranular or intergranular, local chemical environment inside the cracks etc.