Lopez A complete experimental characterization is developed for the mechanisms involved in the stress corrosion cracking (SCC) of alloys 600 and 690 used for pressurized water reactors and specially in steam generator tubing. The active mechanisms for integranular SCC suceptibility of these alloys are identified. Such findings disclose the mechanistic aspects associated with crack propagation during intrergranular SCC in milled annealed alloys 600 and 690. It is assessed whether cavities or micro-fisures are generated at the root of the crack tip due to methane bubble evolution. This information is vital for the safe operation of nuclear power plants.***