Tadman wrote:I would be open to hearing from a metallurgist, but the concept of salt or ice melt rusting railroad rails is not a thing. Rust usually happens when water is trapped and sits near thinner metals and can work over time. This is why the rust spots are usually toward the bottom of the body of a car or train, as water pools at the bottom and sits there and acts over time on the sheet steel.
Think about rail - it's very thick and hard, and it sits on a surface specifically designed to drain water not just off the rail, but away from the ties and ballast as well.
Ergo the line of logic that sandite may or may not be made of a substance that rots rails doesn't have much to do with anything. It's awfully hard to do anything other than surface rust on rails.
Frame rails on a locomotive, sure, but it would take a long time. Fatigue cracking is much more likely, which also increases the odds of corrosion dramatically (small fissures trap corrosive chemical mixtures like salt water and sulfur dioxide from exhaust, and they overwhelm the passivation provided by the chrome in stainless.) It also happens in railroad rails, starting with pitting & stress fractures and leading to spalling and catastrophic failures. No idea what Sandite contains, but unless there is a salt, caustic, or acidic ingredient, or it attracts moisture (is hygroscopic), it likely isn’t a major contributor to corrosion.
(Not a metallurgist, but related to one who has explained this process to me more time than I can count.)