Stainless steel refers to any type of steel with high contents of alloying elements and the capability of corrosion-resistance in corrosive atmospheres and high temperatures. The ordinary stainless steel contains iron and carbon and a minimum of 11% chromium that is the main factor in its resistance against corrosion
There are more than 100 grades of steel that are classified into five families. The most important category of this family includes the austenitic steels that contain about 16-26% chromium and, depending on their application (environment and working temperature), up to 26% nickel along with low carbon content. The steels in this category lack the magnetic properties and, thus, are known as the non-magnetic steels. Also, they cannot harden via heat treatment. Among the most important instances of the austenitic steels, the 304 and 316 stainless steel sheets can be mentioned.
The 410 and 420-steel sheets are of the martensitic type and are heat treatable. But the steel 430 sheet is ferrite steel without heat treatability. All of these three types of steel have magnetic properties and are absorbed by a magnet, thus they are known as the magnetic sheets. The 410, 420, and 430 stainless steel sheets will be described in detail below.
As much as the chromium content is increased, the steel's resistance against oxidation and high temperature is increased accordingly. The 300 series stainless steel sheets (austenitic steels), due to their high chromium content (a minimum of 18%), can tolerate the temperatures of up to 870°C without being oxidized. The grades such as 309 and 310 heat-resistant stainless steel sheets can resist against oxidization at temperatures of up to 980°C and 1035°C, respectively.