IGC Test

http://www.google.co.uk/search?sourceid=navclient-menuext&ie=UTF-8&q=Intergranular+corrosion+test+for+SS

A common one is to soak the stainless in a solution of salt water and reagent or technician grade H2O2 to accelerate the corrosion. Then after a set time period perform macroscopy (<60x optical power) to determine the rate of intergranular and exfoliation corrosion. The time period the SS spends in solution depends on how long you want to simulate at sea level, and like nearly everything there are ASTMs and ISOs for this test.

ASTM A262 standard includes five different detailed practices. It's the most common standard for this purpose.

There are some others, like EURONORM 114 (similar to old DIN 50914) but it only deals with one of the practices (the Monypenny-Strauss test with copper sulfate in sulfuric acid)

Cheers