Case 1475 ยท Public preview
Internal Corrosion Can Obscure the Defect You Expected to Find
A steel tube was examined for its metallurgical and surface condition, including a suspected fatigue-prone region at an internal bend.
SEMEDSLongitudinal microsectioningTransverse microsectioningOptical metallographyComposition and hardness testing
What the evidence preview establishes
The tube interior was dominated by severe rusting rather than a detectable fatigue crack. Gas-pocket and vent-like morphology, together with localized sulfur, made microbiologically influenced corrosion a credible possibility, although it was not proven.
Why this case matters
When corrosion has consumed the surface of interest, separate observations from mechanism claims. Document internal-versus-external severity, section beneath the scale to search for cracking, analyze unusual deposits, and retain a new-part baseline before assigning MIC or fatigue.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, four interpreted figures, alternative explanations, limitations, and practical application guidance.