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How is Stainless Steel Made?

Stainless steel is often used to make appliances because it is durable and strong.
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  • Written By: Y. Chen
  • Edited By: O. Wallace
  • Last Modified Date: 17 October 2014
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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.

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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.

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anon175510
Post 11

Some of the ferritic can go as low as 10.5 chrome. A lot of the authenitics are 16-18 requirement.

anon139790
Post 9

Regarding chromium leakage, a meal prepared with stainless steel cookware gives you about 45 micrograms of chromium, which is not enough to cause concern, according to Health Canada.

anon93782
Post 8

If chromium is present in some significant percentage (10 percent or 12 percent or whatever) in order for steel to be "stainless", and if - as the article states - "chromium oxide forms a film non-detectable to the naked eye on the surface of the steel", then wouldn't chromium oxide leach directly into food prepared on a stainless steel surface? For example, wouldn't chromium oxide leach directly into ice cubes made in a stainless steel ice cube tray?

anon78347
Post 6

i have a circular saw with a steel cutting disk. why can't i cut stainless steel?

what makes it so hard? is chromium what makes it hard, or temper or what?

anon63643
Post 5

For a stainless steel product to show signs of rust, what would be the problem? The manufacturer claims that the stainless steel is 304 grade and that they use 8.3 percent Ni.

anon52069
Post 4

The minimum for chromium is 12 percent for steel to be a true stainless. Also stainless is not by nature low carbon, it can be whatever the maker wants it to be, the same as any steel. As a custom knife maker I work with high carbon stainless all the time, mostly with 440C and ATS34, both of which are above 1.0 percent carbon.

Having worked in a steel mill for 32 years and five years in the galvanizing (zinc) end I don't believe it's possible to coat stainless because of the chromium oxides that form on the surface. besides, it's stainless. why would you need to?

anon621
Post 2

According to another website, stainless steel is at least 10 percent chromium by weight. If other sources dispute this please let the editors know so that they can make the appropriate changes to this article. Thank you.

anon202
Post 1

For stainless steel I thought that the minimum composition of chromium must be 12% and not ten and if it is less than 12% then it is not considered a stainless steel because then the protective layer won't be able to form. Can stainless steel be galvanized? If so, by using which coating and if not then why not?

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