Stainless steel is manufactured by a range of smelting methods that are typical of most metallurgical processing. Three of the common processes are listed below:
An electric arc furnace uses a high current flowing between two carbon electrodes to heat the raw materials. Alloying elements of scrap and pre-made steel, chromium, etc. are added to the furnace crucible, along with iron ore and the necessary additions to refining this component, to create the stainless steel alloy. Melting and refinement occur in the furnace and the impurities float off as slag/clinker.
Blast furnaces melt iron ore mixed with coke in the crucible, blowing oxygen through the molten iron to remove impurities that float off as slag. Once the ore has been purified, chromium and other alloying elements are added to the molten metal to create the stainless steel alloy.
Vacuum induction melting and vacuum arc melting produce very high-purity metals, from already refined source materials (i.e., no ore is added). This process allows for more precision in the control of the composition of stainless steel alloys.
Once the stainless steel has been melted and refined, it will generally be rough cast into billets. These billets are then formed into various shapes and sizes using a range of manufacturing processes, including:
The casting of stainless steel involves molten metal being poured into a cast cavity, to which it conforms and the cast retains the cavity shape when cooled.
Rolling of stainless steel sees the raw billets pass through a series of precise pinch rollers, to reduce their thickness and shape the steel into sheets or other forms. This process can be performed hot or cold, to produce a variety of final materials of diverse strengths and crystalline structures.
The forging of stainless steel requires it to be heated and then shaped by hammering or pressing it into the desired form.
Machining stainless steel enables it to be cut and shaped using various machines, such as lathes and mills.
After the stainless steel has been formed into its final shape, it may undergo additional processing to improve its properties, such as heat treatment, polishing, or coating.