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What are the 4 basic elements required for corrosion to happen?
What are the 4 basic elements required for corrosion to happen?
Anode, Cathode, Electron flow, Path
Where is the anode located in the corrosion of steel under a drop of water?
Where is the anode located in the corrosion of steel under a drop of water?
Fe
What is the corrosion mechanism for Carbon Steel as described in the content?
What is the corrosion mechanism for Carbon Steel as described in the content?
Fe → Fe2+ + 2e : anode; O2 + 2H2O + 4e → 2OH- : cathode; Fe2+ + 2OH- → Fe(OH)2 : insoluble hydroxide
What are the main methods mentioned in the content to control corrosion?
What are the main methods mentioned in the content to control corrosion?
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What is meant by damage mechanism as explained in the content?
What is meant by damage mechanism as explained in the content?
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Study Notes
Corrosion Mechanism
- Corrosion requires four basic elements: anode, cathode, path, and electron flow
- The anode is where oxidation occurs, and the cathode is where reduction occurs
Corrosion of Steel
- The corrosion mechanism for carbon steel involves two half-reactions:
- Anode: Fe → Fe2+ + 2e
- Cathode: O2 + 2H2O + 4e → 2OH-
- Overall reaction: Fe2+ + 2OH- → Fe(OH)2 (insoluble hydroxide, white-green)
Rust Formation
- Fe(OH)2 can further react to form different types of rust:
- Fe(OH)3 (black magnetite)
- γ-Fe3O4 (brown rust)
- γ(FeOOH) (yellow rust)
- Fe2O3 (reddish-brown rust)
Controlling Corrosion
- Methods to control corrosion include:
- Material selection and design
- Corrosion inhibitors and monitoring
- Coatings and linings
- Cathodic protection
Damage Mechanisms
- Damage mechanisms are processes that result in asset degradation, including corrosion
- Some damage mechanisms occur before or after an asset is put into service
- Examples of damage mechanisms include:
- Hydrogen attack, including:
- High-temperature hydrogen attack (HTHA)
- Hydrogen embrittlement (HE)
- Hydrogen blistering
- Hydrogen-induced cracking (HIC)
- Stress-oriented hydrogen-induced cracking (SOHIC)
- Hydrogen attack, including:
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Description
This quiz covers the basics of corrosion, including the mechanism and theory of corrosion, the behavior of metals in different environments, and the identification of the 4 basic elements necessary for corrosion to occur.
