The Armour Archive

Has anyone noticed a difference in the type/texture of rust formed on different types of commercially available modern steels?

IE "Under the same storage conditions, I've noticed that mild steel forms big fat rust clumps while 1050 forms a multitude of small pinhead sized bumps and 4130 tends to form a very fine dusting of rust."

I TOLD you it was a strange question.

Alcyoneus:

Sounds like a question for the Great Guru at Anvilfire, but I'll take a crack at it.

I also have observed different rust patterns on different allows of steel. The most common mentioned is the "wood grain" on wrought iron; but I've also seen wrought iron pit like modern mild steel, according to condition. Consistent conditions are the trick. Most rust begins with microscopic galvanic reactions, so any surface coating, or difference in exposure, or even chemicals from the skin of the person(s) who handle the steel could possibly promote different patterns of rust. Still, there are a number of alloys that are more (or less) resistant to rust. Given the higher carbon content, I would expect more extensive rust in the 1050 vs. 1020 mild carbon steel. Perhaps the molybdenum in the 4140 makes it more resistant. (Some of the stainless steels have from .75 to 3 % Mo, although they get their rust resistance primarily through their high chromium content, as much as 21%.) So steels rust at varying rates, and in varying ways, but what you are observing MAY be the results of subtle variations in coating, handling and/or storage.


------------------
Full time civil servant, part time blacksmith, and seasonal Viking ship captain.

Visit your National Parks: www.nps.gov

Go viking: www.longshipco.org/

Hit hot iron: www.anvilfire.com

Markland Medieval Mercenary Militia: http://www.markland.org

I wonder if rust is like a watched pot?

No, I'm not really observing anything more than normal, just a question for future reference.

You could try to make an identification process for metal based on rust.. it could be useful do recognive what we have at hand when we go to scrapyards.