Pitting Pitting, just as it sounds, is used to describe the formation of small pits on the surface of a metal or alloy. Pitting is suspected to occur in much the same way crevice corrosion does, but on a flat surface. Pitting can go on undetected for extended periods of time, until a failure occurs. A textbook example of pitting would be to subject stainless steel to a chloride containing stream such as seawater. Pitting would overrun the stainless steel in a matter of weeks due to it's very poor resistance to chlorides, which are notorious for their ability to initiate pitting corrosion.
Titanium is usually the material of choice if chlorides are the main corrosion concern.
Intergranular Corrosion Occuring along grain boundaries for some alloys, intergranular corrosion can be a real danger in the right environment. The heating of some materials causes chromium carbide to form from the chromium and the carbon in the metals. This leaves a chromium deficient boundary just shy of the where the metal was heated for welding. To avoid this problem, the material can be subjected to high temperatures to redissolve the chromium carbide particles. Low carbon materials can also be used to minimize the formation of chromium carbide.