Posted by SMP on June 30, 2008 at 17:09:50:
In Reply to: Rust Characteristics of SS439 and 1018 Steel posted by Rhonda Hosler on June 27, 2008 at 09:52:43:
Generally, iron and steel will not exhibit red rust when exposed to air with a relative humidity below 50%. Instead, a passive layer of magnetite will form. This explains why metallographic specimens will not etch if left lying around for a while.