Galvanic Corrosion Risk Analyzer — Galvanic Current Index & Corrosion Severity Calculator
Calculate galvanic current index using material potentials, cathode/anode area ratio, electrolyte conductivity, environment factor, and polarization factor.
Enter the known values and review the calculated result
Input parameters
Use consistent values and select the intended engineering units.
Electrochemical potentials
Geometry
Environment & electrolyte
Polarization
Results
Engineering Pro Save, document and continue this calculation
Turn this result into a reusable engineering record with saving, PDF export and reporting workflows.
Method, application and limitations
Review the calculation method, intended application and engineering assumptions before using the result in a design decision.
Formula and calculation method
Galvanic current index formula:
ΔE = |E1 − E2|
RA = Acathode / Aanode
κeff = log10(1 + 10κ)
φpol = 1 / (1 + log10(1 + fpol))
φgeom = 1 + log10(1 + RA)
Ig,raw = ΔE · κeff · φpol · φgeom · fenv
Ig = log10(1 + 10Ig,raw)
Corrosion severity index formula:
η = max(0, min(5, Ig / 3))
where:
- Ig — galvanic current index [−]
- η — corrosion severity index [−]
- ΔE — potential difference between material 1 and material 2 [V]
- E1 — material 1 potential [V]
- E2 — material 2 potential [V]
- RA — cathode-to-anode area ratio [−]
- Acathode — cathode area [m²]
- Aanode — anode area [m²]
- κ — electrolyte conductivity [S/m]
- κeff — stabilized electrolyte conductivity effect [−]
- fenv — environmental factor [−]
- fpol — polarization factor [−]
- φpol — polarization protection factor [−]
- φgeom — geometry severity factor [−]
When to use this calculator
When to use this calculator:
- Evaluate galvanic corrosion risk between two materials with different electrochemical potentials.
- Check how a large cathode area relative to anode area increases the corrosion severity index.
- Compare electrolyte conductivity conditions using the stabilized conductivity effect in the galvanic current index formula.
- Assess whether environmental factor and polarization factor push the result into safe, limit, warning, or unsafe status.
- Identify which material acts as the anode and which material acts as the cathode from the input potentials.
How to interpret the result
Galvanic current index is defined as a dimensionless stabilized index based on potential difference, electrolyte conductivity effect, polarization protection factor, geometry severity factor, and environmental factor.
Corrosion severity index is defined as the galvanic current index divided by 3 and limited to the range from 0 to 5.
The result depends on potential difference, cathode-to-anode area ratio, electrolyte conductivity, environmental factor, and polarization factor. Increasing potential difference increases both galvanic current index and corrosion severity index. Increasing cathode area relative to anode area increases geometry severity. Increasing electrolyte conductivity increases environmental severity. Increasing polarization factor decreases the polarization protection factor used in the galvanic current index formula.
- Safe — corrosion severity index ≤ 0.5, potential difference ≤ 0.4 V, and cathode-to-anode area ratio ≤ 5.
- Limit — corrosion severity index > 0.5, while warning and unsafe conditions are not reached.
- Warning — corrosion severity index > 1.2, or potential difference > 0.4 V, or cathode-to-anode area ratio > 5.
- Unsafe — corrosion severity index > 2.5, or potential difference > 0.7 V, or cathode-to-anode area ratio > 20.
- Invalid — at least one required input is outside its allowed mathematical domain.
The result is used to evaluate whether the material pair, area ratio, electrolyte conductivity, environmental factor, and polarization factor produce a low, limited, warning-level, or unsafe galvanic corrosion risk.
Calculation example
Example:
A user checks a two-material joint where material 1 has a lower potential than material 2, the cathode area is larger than the anode area, and the electrolyte has finite conductivity.
- Material 1 potential: E1 = −0.50 V
- Material 2 potential: E2 = −0.10 V
- Cathode area: Acathode = 0.020 m²
- Anode area: Aanode = 0.004 m²
- Environmental factor: fenv = 1.5
- Electrolyte conductivity: κ = 0.05 S/m
- Polarization factor: fpol = 2
The calculated galvanic current index is Ig = 0.356, and the corrosion severity index is η = 0.119.
Assumptions and limitations
- The model uses absolute potential difference between material 1 and material 2.
- Cathode-to-anode area ratio is calculated as cathode area divided by anode area.
- Electrolyte conductivity effect is stabilized using log10(1 + 10κ).
- Geometry severity factor is stabilized using 1 + log10(1 + cathode-to-anode area ratio).
- Polarization protection factor is calculated as 1 / (1 + log10(1 + polarization factor)).
- Corrosion severity index is limited to the range from 0 to 5.