Corrosion behaviour of iron alloys, does it depend oncomposition or corrosion environment?

Iron alloys mainly steels are used widespread for long period of time. According to thermodynamics these are prone to corrosion. Corrosion behaviour is described as dependant on alloy composition and corrosion environment. It is supposed the most important is the composition which implies where the alloy will resist and the corrosion environment which implies what corrosion products are formed. However this simplification may not be utterly true. The capability to resist corrosion depends on material composition for sure. But the phase composition of corrosion products is dependant mainly on corrosion processes, not only the corrosion environment in general. Similar or nearly identical corrosion products were obtained by corrosion in different environments, corrosion in soils and corrosion in outdoor atmosphere. Under both conditions layered structures formed of Lepidocrocite, Maghemite and Goethite has been formed. This is in agreement with the theoretical corrosion process description but is not with the simplified corrosion models. This does not mean automatically the simplified models are completely wrong; it does mean however these simplified models need revision. The general environment description is not sufficient to describe what is going on in the environment.