Case 1770 ยท Public preview
Crevice Conditions Can Attack Nickel-Phosphorus Coating and Stainless Fittings
Water-exposed stainless assemblies developed rust-colored deposits concentrated where coated rods entered closely fitted holes.
Optical microscopyMicrosectioningSEMEDSCoating examinationControl comparison
What the evidence preview establishes
Crevice corrosion attacked nickel-phosphorus coating on the rods and stainless steel inside the fitting. Nonuniform protective coating, oxygen-depleted geometry, and uncontrolled dissolved water species created a credible coupled corrosion environment.
Why this case matters
Filtered water is not necessarily ion-free or noncorrosive. For coated stainless assemblies, control crevice geometry, coating continuity, water chemistry, dissolved oxygen, and residues from bore-finishing operations.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, four interpreted figures, alternative explanations, limitations, and practical application guidance.