ABSTRACT
In the presence of moisture the situation changes drastically and the loss of metal by corrosion becomes much more significant. A major consideration in this is corrosion. This involves loss of material from the metal’s surface and can be divided into two processes: dry oxidation and wet corrosion. Corrosion rates are also temperature dependent; for example mild steel in aerated water corrodes six times faster at 100°C than at 0°C. There are some circumstances in which wet corrosion can occur at selected localised sites. In these circumstances the corrosion can be intense and lead to premature failure of a component rather than generalised loss of material. The localised corrosion is a consequence of a difference in the constitution of the electrolyte itself. The lower, oxygen-deficient layers are anodic and corrosion occurs locally. At ambient temperatures significant corrosion occurs only if moisture is present.
