How is Stainless Steel Made?

Stainless steel has been touted for its ubiquitous practical uses, making appearances in the architectural, automotive, kitchen, home, and industrial applications of manufacturing. It contains a high resistance to corrosion resulting from a range of atmospheric conditions and extreme changes in pH, making it low maintenance. Its ability to withstand high magnitudes of temperature in both directions, high pressure, and still be malleable and ductile makes stainless steel the ideal material for fashioning lasting, highly used products. Even after its useful life, this material is easy to recycle and fetches a high scrap value.

This metal attributes its unique properties to chromium metal. By nature, stainless steel is a low carbon steel that includes at least ten percent chromium metal by weight in its composition. This is what is responsible for its stainless property. The chromium oxide forms a film non-detectable to the naked eye on the surface of the steel, which is flexible and self-healing in the presence of oxygen gas.

Stainless steel itself is made in an electric arc furnace. Within the furnace, carbon electrodes that are positioned to make contact with scraps of steel blast currents through them. The scraps of steel do not only have to be mixed with chromium. Other elements can be added to enhance the steel, including nickel, nitrogen, and molybdenum. All of this electrode-induced activity takes place in a very high temperature environment.

Upon reaching the critical melting point, the steel scraps and alloys start intermixing until the result is one homogeneous metal fusion. The whole mass is then transferred to an argon oxygen decarbonization (AOD) vessel where deoxygenization occurs. Afterward, casting or forging can be done. Because of its malleable and ductile abilities, the metal can be manipulated into a variety of shapes and forms, or drawn into wires.

As a finishing touch, an electro chemical process can treat the steel into different colors, some of them being gold, bronze, green, blue, and black. Another optional finishing touch is dipping the product in an acid bath, which eliminates any scaling on the stainless steel for a better polished appearance and easy cleanability after usage.

There exists at least sixty grades of stainless steel, categorized by the alloy elements of its microstructure. Within these grades are three main types of stainless steel, namely Martenistic, Ferritic, and Austenitic. These main types differ depending on degree of magnetism, the percentage of chromium, and the proportion of the other elements.