What is Stainless Steel?
The development of Stainless Steel
In metallurgy, stainless steel is defined as an iron-carbon alloy with a minimum of 10.5% chromium content. The name originates from the fact that stainless steel does not stain, corrode or rust as easily as ordinary steel (it “stains less”, but is not actually stain proof). This material is also called corrosion resistant steel when it is not detailed exactly to its alloy type and grade, particularly in the aviation industry.
A few corrosion-resistant iron artifacts survive from antiquity. A famous (and very large) example is the Iron Pillar of Delhi, erected by order of Kumara Gupta I around the year AD 400. However, unlike stainless steel, these artifacts owe their durability not to chromium, but to their high phosphorus content, which together with favorable local weather conditions promotes the formation of a solid protective passivation layer of iron oxides and phosphates, rather than the non-protective, cracked rust layer that develops on most ironwork.
The corrosion resistance of iron-chromium alloys was first recognized in 1821 by the French metallurgist Pierre Berthier, who noted their resistance against attack by some acids and suggested their use in cutlery. However, the metallurgists of the 19th century were unable to produce the combination of low carbon and high chromium found in most modern stainless steels, and the high-chromium alloys they could produce were too brittle to be of practical interest.
This situation changed in the late 1890s, when Hans Goldschmidt of Germany developed an aluminothermic (thermite) process for producing carbon-free chromium. In the years 1904–1911, several researchers, particularly Leon Guillet of France, prepared alloys that would today be considered stainless steel.
In Germany, Friedrich Krupp Germaniawerft built the 366-ton sailing-yacht “Germania” featuring a chrome-nickel steel hull in 1908. In 1911, Philip Monnartz reported on the relationship between the chromium content and corrosion resistance. On October 17, 1912, Krupp engineers Benno Strauss and Eduard Maurer patented austenitic stainless steel.
Similar industrial developments were taking place contemporaneously in the United States, where Christian Dantsizen and Frederick Becket were industrializing ferritic stainless.
However Harry Brearley of the Firth-Brown research laboratory in Sheffield, England is most commonly credited as the “inventor” of stainless steel, but many historians feel this is disputable. In 1913, while seeking an erosion-resistant alloy for gun barrels, he discovered and subsequently industrialized a martensitic stainless steel alloy. The discovery was popularized a few years later, in a January 1915 newspaper article in the New York Times.
1. Stainless steel was particularly in vogue during the art deco period. The most famous example of this is the upper portion of the Chrysler Building (illustrated above). Diners and fast food restaurants feature large ornamental panels, stainless fixtures and furniture. Owing to the durability of the material, many of these buildings still retain their original and spectacular appearance.
2. In recent years the forging of stainless steel has given rise to a fresh approach to architectural blacksmithing. The work of Giusseppe Lund illustrates this well.
3. Also pictured above, the Gateway Arch is clad entirely in stainless steel: 886 Tons (804 metric tonnes) of 1/4″ (6.3 mm) plate, #3 Finish, Type 304.
4. Type 316 stainless is used on the exterior of both the Petronas Twin Towers and the Jin Mao Building, two of the world’s tallest skyscrapers.
5. The Parliament House of Australia, in Canberra, Australia, has a stainless steel flagpole weighing over 220 tonnes.
6. Stainless Steel is the fourth common material used in metal wall tiles, and is used for its corrosion resistance properties in kitchens and bathrooms.
7. The aeration building in the Edmonton Composting Facility, the size of 14 NHL hockey rinks, is the largest stainless steel building in North America.
8. The United States Air Force Memorial has an austenitic stainless steel structural skin.
What is the function of stainless steel?
Stainless steels of various kinds are used in thousands of applications. The following gives a flavour of the full range:
Domestic – cutlery, sinks, saucepans, washing machine drums, microwave oven liners, razor blades
Architectural/Civil Engineering – cladding, handrails, door and window fittings, street furniture, structural sections, reinforcement bar, lighting columns, lintels, masonry supports
Transport – exhaust systems, car trim/grilles, road tankers, ship containers, ships chemical tankers, refuse vehicles
Chemical/Pharmaceutical – pressure vessels, process piping.
Oil and Gas – platform accommodation, cable trays, subsea pipelines.
Medical – Surgical instruments, surgical implants, MRI scanners.
Food and Drink – Catering equipment, brewing, distilling, food processing.
Water – Water and sewage treatment, water tubing, hot water tanks.
*The article was collected and revised by WELLGREEN PROCESS SOLUTIONS – Sanitary Stainless Steel Tubing and Fittings.