Stainless steel, also known as inox steel, is a steel alloy that can contain a number of different chemicals in varying degrees including: iron, carbon, chromium, nickel, niobium, molybdenum, and titanium.
History
English metallurgist Harry Brearley wasn’t looking to invent stainless steel, he was searching for a way to improve the barrel of a rifle. But in 1913, Brearley discovered that adding chromium to low carbon steel makes it resistant to stains.
The science underlying the rust resistant properties of stainless steel involves the combination of chromium and oxygen. The two elements form an invisible layer of chrome-containing oxide, which coats the surface of the metal. This layer of protection is extremely thin, but if it is scored or scratched, a new layer quickly forms to prevent the surface underneath from being corroded. Accordingly, in an oxygen poor environment, stainless steel is less effective at preventing rust.
Today, the term stainless steel is used to define a group of rust resistant steels that have a minimum of 11% chromium. Stainless steel is used across a wide range of industries with suppliers selling steel to aircraft, appliance, and auto manufacturers, as well as construction companies. Stainless steel arches adorn the Chrysler Building and were used to build Apollo 11. Sheffield, England, where Brearley made his discovery, is a major exporter of stainless steel products.
Types of Stainless Steel
There are three main types of stainless steel: austenitic, ferritic, and martensitic, each of which is named for the solid solution in the main phase of stainless steel production. Austenitic steel is typically classifed as the 200 and 300 series according to the American Iron and Steel Institute. The most common form of stainless steel, austenitic steel is non-magnetic and can't be heat treated. Ferritic steel is magnetic and can reduce the possibility of steel cracking when it is heated. Ferritic, along with Martensitic, make up the bulk of the 400 series of stainless steel classification. Martensitic steel is magnetic, typically has a higher carbon and lower chromium content, and often cracks during welding, so it must be heated more slowly.
When austenite and ferrite are combined in a single material, the result is duplex stainless steel, which is more resistant to corrosion and is twice as strong as either compound individually. Precipitation hardening steel combines the properties of austenitic and martensitic steel to create a machine ready product. Afterwards a low-temperature heat process, known as ageing or age-hardening, can be applied to increase the strength of the steel. Each requires a different welding technique.
Passivation is another process by which stainless steel is treated in an effort to make it more resistant to corrosion. The steel is bathed in an acidic solution, such as citric acid, that cleans the surface and is believed to help improve the formation of the protective passive layer.
Stainless Steel Products
Stainless steel has been used in a number of different products because it doesn’t corrode or rust easily and is available in a number of finishes and textures. Many people choose stainless steel for kitchen products such as range hoods and countertops. They were initially popular in commercial kitchens because of the surface’s reistance to heat and lack of seams to trap germs.
Stainless steel is a common choice for flatware as well. Stainless Steel Flatware packaging usually has a number on the packaging such as 18/10, 18/8, or 18/0. This refers to the amount of chromium and nickel in the raw materials used to make the silverware. Nickel is what protects the flatware from corrosion.
When it comes to stainless steel grills, a buyer should look at the grade, thickness, finish, and assembly of the metal.
Concerns over the safety of plastic water bottles has led to a surge in popularity of stainless steel thermoses and water bottles.
How To Clean Stainless Steel
Although stainless steel is resistant to rust, any grime that accumulates increases the risk of corrosion. Brown stains on stainless steel can often be treated with a baking soda solution or Barkeeper’s Friend powder.
Stainless steel can be scratched or dented easily, but the following four cleaning methods won’t scratch the surface and are safe for cleaning up spills or dirt:
- Warm water and a cloth will cover basic cleaning chores.
- Mild detergent or dishwashing liquid and a towel for caked on grime.
- Glass cleaner, water, and a dry towel can erase fingerprints.
- Stainless steel cleaners can help with staining, scratching, or polishing. Always read the directions and check the ingredients before using.
A number of different manufacturers also make stainless steel cleaners, Scotch-Brite is a familiar brand of cleaner, while Bayes Eco-Friendly cleaner is a green option. Some owners choose to make their own cleaner.
Remember to always dry the surface with a clean towel because water can leave mineral deposits that stain. Don’t use either chlorine or steel wool on stainless steel, both will scratch the surface.
Did You Know?
It has been suggested that stainless steel can help remove odors from your hands, if you rub your hands across the metal after cutting fish or onions, for example.
Related Stainless Steel Resources
About.com BBQ: Stainless Steel Grills [1] About.com Chemistry: How Does Stainless Steel Remove Odors? [2] About.com Chemistry: Stainless Steel [3] About.com Coffee & Tea: Top 5 Top Thermoses and Thermal Bottles [4] About.com Green Living: Bayes Stainless Steel Cleaner [5] About.com Frugal Living Homemade Cleaner [6] About.com Housekeeping: How Can I Remove Brown Stains from Stainless Steel? [7] About.com Housekeeping: Stainless Steel [8] About.com Housekeeping: Stainless Steel Cleaner [9] About.com Housekeeping: Stainless Steel Cleaning Methods [10] About.com Housekeeping: Stainless Steel Countertops and Heat Resistance [11] About.com Housekeeping: Stainless Steel Don'ts [12] About.com Housewares: Flatware [13] About.com Housewares: Scotch-Brite [14] About.com Interior Decorating: Stainless Steel Countertops [15] About.com Metals: Stainless Steel [16] About.com Metals: Steel Suppliers [17] About.com Walking: Where Can I Find BPA-Free Water Bottles? [18] British Stainless Steel Association: The Discovery of Stainless Steel [19] Gowelding: Duplex Stainless Steels [20] Greyfeather Toys: History of Stainless Steel [21] Products Finishing Online: Citric Acid [22] Products Finishing Online: Passivation of Stainless Steel [23] Stainless Processing, Inc.: 300 Series [24] Stainless Processing, Inc.: Ferritic Steel [25] The A to Z of Materials: Martensitic Steel [26] The A to Z of Materials: Precipitation Hardening Steel [27] The British-Canadian Trade Chamber of Trace and Commerce: Sheffield, England [28] The Fabricator.com: Duplex Stainless Steel [29] Welding Engineer: Stainless Steel Welding Technique [30]