What's the difference?

[sk10009]

Good morning~

What is the difference in using say between pit and lacal corrosion and between local corrosion and general corrosion?

thanks

 

[metengr]

In general, there are eight forms of corrosion. The web site below provides a general explanation of some of these corrosion mechanisms

http://www.materialsengineer.com/CA-corrosion.htm

 

[EdStainless]

I usually break it down a bit differently.
1. Local corrosion includes both pitting and crevice. Fouling and MIC drive these forms of attack.
2. Environmentally assisted cracking, like stress corrosion cracking.
3. General corrosion is uniform attack. This is rare in stainless.
4. Intergranular corrosion, most commonly from sensitization.
5. Galvanic corrosion.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[mshimko]

Here's another take I find useful when explaining things to others; there are exceptions, of course, but I think you'll get the idea:

All aqueous corrosion is galvanic. What sets up the galvanic cell is how we further categorize the type of corrosion.

Uniform: caused by microscopic & fluctuating dipoles.
Pitting and crevice corrosion: caused by geometry
Galvanic: aused by different materials.
etc.