What kind of steel is stainless steel

Steel is a general term for iron-carbon alloys with a carbon content between 0.02% and 2.11%.

Rust usually refers to oxides produced on the surface of metals (including alloys). In this sense, many metals will rust.

In general, rust on the surface of steel is not a good thing. But in fact, it is not. The reason why many steels do not rust in the air is because the rust produced forms a strong and dense protective film on the surface of the steel to separate it from the air, thereby protecting the internal structure from continuous corrosion. The most common aluminum products in our lives are like this.

Rust can be a hazard because iron or iron alloys will form iron trioxide（Fe2O3）compounds on the surface when they come in contact with air. The structure of this rust is very loose, so oxygen and moisture will continue to penetrate, forming an oxidation reaction, until the steel is completely corroded and completely oxidized.

In summary, the so-called stainless steel is an iron alloy that will not be corroded in air or a weak acid environment. "Acid-proof steel" should be used in a strong acid environment. Generally speaking, acid proof steel has the characteristics of stainless steel, and stainless steel is not necessarily acid proof