A piece of corroded steel plate was found in a submerged ocean vessel. It was estimated that the original area of the plate was 17 in.2 and that approximately 2.1 kg had corroded away during the submersion. Assuming a corrosion penetration rate of 200 mpy for this alloy in seawater, estimate the time of submersion in years. The density of steel is 7.9 g/cm3.

4.8 years

Explanation:

The rate of corrosion (CPR) is defined as the rate at which a metal corrodes in a specific environment. It depends on the environmental condition and the type of metal. It is expressed in inches per year or melts per year. CPR is given by:

Where K is a constant = 534, W is the weight corroded = 2.1 kg = 2.1 × 10⁶mg, A is the area = 17 in², ρ is the density = 7.9 g/cm³

From the CPR equation: