Originally Posted by lewishamilton
I'm no expert in materials science, but a quick google search on surface rust got me this:
"Surface rust is flaky and friable, and provides no protection to the underlying iron, unlike the formation of patina on copper surfaces."
and Steel is made of:
"Steel is an alloy made by combining iron and other elements, the most common of these being carbon."
So is surface rust on steel actually protective??
Wikipedia is NOT a valid reference for much of anything technical.
Try this regarding rust as a form of protection:
At a generic level, "steel" IS an alloy by definition. But there's a multitude of different steel alloys. In fact there are dozens of different alloys utilized in a typical car based on the desired characteristics of a given component/body section. That crash bar in the dash is designed to retain it's shape in a side impact collision so it's a high strength alloy. The seats are designed to deform and absorb energy in a collision, but they need to withstand many years of constant abuse, so they're a medium strength alloy. Neither of these are mild steel which is what everyone is most familiar with when it comes to rust and corrosion. Mild steel will eventually rust away to nothing. More sophisticated alloys will not (at least not when protected from the weather/corrosive environments).