Corrosion Rate Calculator (MPY)
Calculate material degradation in Mils Per Year (mpy)
Calculated Corrosion Rate:
0.00 MPYHow to Calculate Corrosion Rate in MPY
Corrosion rate is a critical metric in materials science and industrial maintenance used to determine the lifespan of metal components. The most common unit of measurement in the United States is MPY (Mils Per Year), where 1 mil equals 0.001 inches.
The standard formula used to calculate the corrosion rate is:
MPY = (W × K) / (D × A × T)
Where the variables are defined as:
- W: Weight loss of the metal specimen in grams.
- K: A constant (534,000) used to normalize units to MPY.
- D: Density of the metal in g/cm³.
- A: Total surface area of the metal specimen in square inches.
- T: Time of exposure to the corrosive environment in hours.
Common Material Densities
| Material | Density (g/cm³) |
|---|---|
| Carbon Steel | 7.86 |
| Aluminum (1100) | 2.71 |
| Copper | 8.96 |
| Stainless Steel (304) | 7.94 |
| Lead | 11.34 |
Interpreting Corrosion Rate Results
Once you have calculated the MPY, use the following general guidelines to assess the corrosion resistance of the material in that specific environment:
| MPY Range | Corrosion Resistance |
|---|---|
| < 1.0 MPY | Excellent (Outstanding) |
| 1.0 – 4.9 MPY | Good (Satisfactory) |
| 5.0 – 19.9 MPY | Fair (Questionable) |
| 20.0+ MPY | Poor (Unacceptable) |
Example Calculation
If a steel coupon (density 7.86 g/cm³) with a surface area of 2 square inches loses 0.05 grams after being submerged for 500 hours:
MPY = (0.05 × 534,000) / (7.86 × 2 × 500) = 3.40 MPY
In this case, the steel has "Good" corrosion resistance in that environment.