The corrosion rate of S355J2WP weathering steel in a high-humidity industrial atmosphere typically ranges between 0.020–0.050 mm/year after stabilization of the protective rust layer (patina). Here's a detailed breakdown:
Key Factors Affecting Corrosion Rate
Initial Exposure (0–24 months):
0.030–0.080 mm/year (loose rust forms before patina stabilizes).
Post-Stabilization (>24 months):
0.020–0.050 mm/year (dense patina reduces corrosion significantly).
Comparison to Ordinary Steel (S355)
S355J2WP corrodes 2–4× slower than carbon steel (S355: ~0.100 mm/year in the same environment).
Industrial Atmosphere Challenges
SO₂/Sulfates (from pollution) may accelerate early-stage rusting but have minimal impact after patina formation.
Chlorides (if present) can disrupt the patina, increasing rates to 0.060–0.100 mm/year.
Design Recommendations
Allow for ~0.05 mm/year thickness loss in calculations.
Avoid stagnant water/dirt traps to ensure uniform patina development.
