Partially exposed plain carbon steel vs submerged plain carb

Partially exposed plain carbon steel vs submerged plain carbon steel what would corrode faster and why?

Solution

Carbon steel is an alloy content, usually less than 0.1 to 1.7% by weight of carbon and manganese ,silicon and copper in little praportions ranging from 0.5 to 1.6% , these levels of addition do not generally produce any remarkable changes in general corrosion behavior , whe carbon steel is exposed to both oxygen and moisture the surface which is exposed will rust sooner than exposing the surface just to water, because steel is made almost entirely of iron.Iron in the first step need oxygen to ionize and the ionized iron ions reacts with water to form FeO(OH) and Fe2O3 nH2O.

On the other hand Carbon steel does not form same rust in water as in air , however, it forms a different type of rust that does not develop as quickly as common rust – FeO(OH), it creates iron(III) hydroxide Fe(OH)3. The rate of corrosion is affected by water and accelerated by electrolytes like salt and presence of other minerals in water. In general the parameters that affect corrosion of metals in water include pH level, oxygen content, water temperature, agitation, the presence of inhibitors, and tide conditions. Steel when provided with both water and the oxygen   in proper praportion will rust sooner than exposing just to water alone.

The presence of salt in the water will slightly increase the rate of oxidation of steel , because salt acts as a catalyst in the reduction reaction of steel.