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CORROSION

CORROSION. CONTENTS. Introduction Forms of Corrosion Uniform Corrosion Pitting Corrosion Stress Corrosion Cracking Crevice Corrosion Erosion Corrosion Intergranular Corrosion Hydrogen Damage Corrosion Fatigue

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CORROSION

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  1. CORROSION

  2. CONTENTS • Introduction • Forms of Corrosion • Uniform Corrosion • Pitting Corrosion • Stress Corrosion Cracking • Crevice Corrosion • Erosion Corrosion • Intergranular Corrosion • Hydrogen Damage • Corrosion Fatigue • Concentration Cell Corrosion • Fretting Corrosion • Dealloying • Corrosion in Concrete

  3. Electrochemical cell A cell in which electrons and ions can flow by separate paths between two materials, producing a current which, in turn, leads to corrosion or plating. The components in an electrochemical cell

  4. Electrochemical corrosion Corrosion produced by the development of a current in an electrochemical cell that removes ions from the material. CORROSION: Degradation of metals and is often called RUST

  5. Examples Car Corrosion

  6. Corrosion of Implants

  7. Portion Of Different Forms Of Corrosion

  8. Uniform Corrosion

  9. Pitting Corrosion

  10. Stress Corrosion Cracking Examples of stress cells Cold work required to bend a steel bar introduces high residual stresses at the bend, which then is anodic and corrodes.

  11. Because grain boundaries have a high energy, they are anodic and corrode.

  12. River Branching Pattern

  13. The arrows indicate the primary crack shown in both pictures Intergranular SCC Of An Aluminum Aerospace Part Changes in alloy heat treatment recommended

  14. Crevice Corrosion Corrosion occurs at the tip of a crevice because of limited access to oxygen.

  15. Erosion Corrosion

  16. Intergranular Corrosion In austenitic stainless steel, precipitation of chromium carbide makes the low Cr austenite in the grain boundaries anodic.

  17. Exfoliation Corrosion

  18. Galvanic Corrosion Example of microgalvanic cells in two-phase alloys : In steel, ferrite is anodic to cementite

  19. Hydrogen Damage Hydrogen Embrittlement of Valve Capscrew Fasteners

  20. Corrosion Fatigue

  21. Corrosion Fatigue Cracks In AISI 1020 Steel In Oil And Gas Downhole Service Corrosion fatigue cracks on the I.D. of a Admiralty brass exchanger tube

  22. Concentration Cell Corrosion Corrosion occurs beneath a water droplet on a steel plate due to low oxygen concentration in the water.

  23. Fretting Corrosion

  24. Dealloying

  25. Photomicrograph of a copper deposit in brass, showing the effect of dezincification (x50).

  26. Filiform Corrosion

  27. Corrosion in Concrete

  28. THANK YOU FOR YOUR KIND ATTENTION

  29. References : • http://corrosion.ksc.nasa.gov • http://www.corrosion-doctors.org • http://www.hghouston.com • The Science and Engineering of Materials, 4th ed Donald R. Askeland – Pradeep P. Phuile’

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