CORROSION1 Classification of Corrosion Mechanisms 1. Uniform corrosion/General corrosion 2. Pitting corrosion 3. Crevice corrosion 4. Stress corrosion 5. Fatigue corrosion 6. Intergranular corrosion 7. Erosion corrosion 8. Hydrogen embrittlement 9. Cavitation 10. Selective leaching 11. Exfoliation 12. Biological corrosion 13. Etc. A.Aquaeous Corrosion B.Atmospheric Corrosion C.High Temperature Corrosion

CORROSION2 UNIFORM CORROSION Classification of corrosion

CORROSION3 PITTING CORROSION Classification of corrosion

CORROSION4 PITTING CORROSION

CORROSION5 CREVICE CORROSION Classification of corrosion

CORROSION6 CREVICE CORROSION Initial stage Later stage

CORROSION7 STRESS CORROSION CRACKING / SCC Classification of corrosion

CORROSION8 INTER- GRANULAR CORROSION Classification of corrosion

CORROSION9 INTER- GRANULAR CORROSION Classification of corrosion

CORROSION10 EXFOLIATION Classification of corrosion

CORROSION11 HYDROGEN EMBRITTLEMENT Classification of corrosion

CORROSION12 EROSION CORROSION Classification of corrosion

CORROSION13 Dealloying CORROSION Classification of corrosion

CORROSION14 BIOLOGICAL CORROSION Classification of corrosion

CORROSION15 Hydrogen and H 2 S Effects  H 2 S decrease pH to 4  Anion sulfide play a role as “poison” which trap H ion at the metal surface and facilitate hydrogen penetration into metal lattice.  Hydrogen induced cracking, hydrogen blistering, hydrogen attack and formation of hydride at the sensitive alloy, will be formed with the presence of H 2 S.  Corrosion product are the soluble Sulfide and sulfide deposit.  At High strength steel, hydrogen stress cracking and sulfide stress cracking could occur.