1. CORROSION

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

3. Electrochemical cell The components in an 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.

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. Car Corrosion Examples

6. Corrosion of Implants

7. Portion Of Different Forms Of Corrosion

8. Uniform Corrosion

9. Pitting Corrosion

13. 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. Stress Corrosion Cracking

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

15. River Branching Pattern

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

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

20. Erosion Corrosion

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

23.  Exfoliation Corrosion

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

28. Hydrogen Damage Hydrogen Embrittlement of Valve Capscrew Fasteners

30. Corrosion Fatigue

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

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

34. Fretting Corrosion

36. Dealloying

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

38. Filiform Corrosion

40. Corrosion in Concrete

41. THANK YOU FOR YOUR KIND ATTENTION

42. References : 1.http://corrosion.ksc.nasa.gov 2.http://www.corrosion-doctors.org 3.http://www.hghouston.com 4.The Science and Engineering of Materials, 4th ed Donald R. Askeland – Pradeep P. Phuile’