Answer:
t = 5.27 years
Explanation:
Firstly, the corrosion penetration rate is defined by the formula;
CPR = (KW)/(ρAt)
Where;
K = constant based on exposed area A.
W - mass lost over time
t- duration
ρ - density
A - area exposed
From the problem, we have;
W = 7.6kg or 7.6 x 10^(6) mg
CPR = 4 mm/yr
ρ = 4.5 g/cm³
Area = 800 cm²
K is a constant valued at 87.6cm
Rearranging the CPR formula to isolate t, we derive;
t = KW/(ρA(CPR))
t = (87.6 x 7.6 x 10^(6))/(4.5 x 800 x 4) = 46233.3 hours
The duration in question needs to be expressed in years.
Thus, converting hours to years;
There are 8760 hours in a year.
Therefore;
t = 46233.3/8760 = 5.27 years.