Case 1182 ยท Public preview
A Thin Galvanized Layer Can Expose Steel and Accelerate Galvanic Corrosion
Galvanized-steel parts developed visible corrosion in a humid service environment while nominally similar products used elsewhere reportedly did not.
Optical microscopyBackscattered-electron SEMEDSMetallographic microsectioningOxide-volume thickness estimation
What the evidence preview establishes
The zinc coating was too thin to provide durable protection. Local ruptures exposed the underlying steel, enabling Fe-Zn galvanic corrosion, while high humidity accelerated the attack; the original zinc thickness was estimated at only about 2 to 4 micrometers.
Why this case matters
Do not attribute galvanized-steel corrosion to visible handling marks alone. Section the coating, identify the corrosion chemistry, and determine whether local breaks and inadequate zinc thickness have exposed steel to a humidity-accelerated galvanic couple.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, four interpreted figures, alternative explanations, limitations, and practical application guidance.