Surface chemistry of cooking
Stainless steel is considered stainless because it has at least 11% chromium by mass. Chromium is a relatively inert metal and does not rust or react as easily as plain carbon steel. This is what makes it an exceptional material for cooking. It is also fairly inexpensive, but does not have a very high thermal conductivity. From a surface standpoint, this is because of the thin layer of chromium oxide that is formed on the surface. This thin layer protects the metal from rusting or corroding. While it is protective, the oxide layer is not very conductive, which makes cooking food less efficient than it could be. For most cooking applications, high thermal conductivity is desirable to create an evenly heated surface on which to cook. In this way, stainless steel is usually not considered high-grade cookware.
Stainless steel
Austenitic stainless steel is the largest family of stainless steels, making up about two-thirds of all stainless steel production. They possess an austenitic microstructure, which is a face-centered cubic crystal structure. This microstructure is achieved by alloying with sufficient nickel and/or manganese and nitrogen to maintain an austenitic microstructure at all temperatures from the cryogenic region to the melting point. Thus austenitic stainless steels are not hardenable by heat treatment since they possess the same microstructure at all temperatures.