Does Stainless Steel Rust?
The question “does stainless steel rust?” is often asked. The short general answer is no, stainless steel does not rust*. We’re going to cover how stainless steel is made, how surface rust can show up on stainless steel, and how to remove surface rust from stainless steel. Let’s get started.
What is stainless steel and how is it made?
Stainless steel is made up of 16% to 36% of Chromium in the ferrous steel. The high amount of chromium is what makes the stainless steel rust resistant. When chromium is exposed to elements including water, air, and acids a layer of chromium(II) oxide layer is developed. This oxide layer is very thin and prevents corrosion.
How can rust form on stainless steel?
The most common occurrence of stainless steel showing rust is when ferrous metals are “rubbed” off onto the surface of the stainless steel. When ferrous metals embed into stainless steel the iron also referred as free iron can rust. The rust is contained to the surface of the stainless steel and will not penetrate beneath the oxide layer. Welding splatter when a flux type welder is used can also cause surface rust on stainless steel. If welding splatter is removed, rust can still form due to a layer of free iron on the surface of the stainless steel.
How can rust be removed from stainless steel?
The good news is that rust on the surface of stainless steel can easily be removed by following proper steps. We’re going to cover two common ways to remove surface rust including chemical cleaning and mechanical cleaning.
Removing rust on stainless steel using chemicals. Commercially available rust remover can be used effectively. When looking for commercially available rust removers look for oxalic acid in the ingredients. A homemade rust remover can be made by combining baking soda and a little water. Rub the wet baking soda paste into the surface rust, wait for a few minutes. With a clean damp cloth wipe the paste away. Dry with paper towels.
Mechanical cleaning can be used by using flapper wheels and or stainless steel wire brushes. Make sure the mechanical cleaning devices are new or uncontaminated by free iron. The goal is to remove the free iron, not smear it around on the stainless steel surface. Be careful not to apply excessive pressure. Pressing too hard with mechanical cleaning can do more damage than good.
Fluid Power Support can design and fabricate your stainless steel and ferrous metal projects. Call us at (573) 581-8200 or stop by our facility at 22398 Audrain Road 9824 Mexico, Missouri.
*Stainless steel does not rust by itself. Free irons are needed for stainless steel to form surface rust.