Why is weathering steel better than normal steel?

"Better" depends what characteristics that are most important to the individual case. The advantage of

weathering steel is that it doesn't have to be painted, In suitable environments weathering steel forms an

adherent protective rust ‘patina’, that inhibits further corrosion. The corrosion rate is so low that bridges

fabricated from unpainted weathering steel can achieve a 120 year design life with only nominal maintenance.

Hence, a well-detailed weathering steel bridge in an appropriate environment provides an attractive, very low

maintenance, economic solution.

Weathering steel, best-known under the trademark Cor-TEN steel and sometimes written without the hyphen

as "Corten steel", is a group of steel alloys which were developed to eliminate the need for painting, and form a

stable rust-like appearance if exposed to the weather for several years.

Weathering steel is a high strength low alloy steel that was originally developed by United States Steel in the

1930s to resist corrosion and abrasion in their ore wagons. It was given the trade name Cor-ten, and was first

used in construction on the John Deere World Headquarters building in Moline, Illinois, which opened in 1964.

Since then, the use of weathering steel has spread worldwide and in Europe it is available as “structural steel

with improved atmospheric corrosion resistance” and is a non-proprietary product.

Weathering steel is popularly used in outdoor sculptures, such as in the large Chicago Picasso sculpture, which

stands in the plaza of the Daley Center Courthouse in Chicago, which is also constructed of the same Cor-

TEN steel and as exterior facades, for its rustic antique appearance.

The first weathering steel bridge in the UK was a footbridge at York University in 1967 and the material was

used for many bridges around the UK in the following 30 years or so. However, the use of weathering steel on

bridges has increased significantly since 2001 when a former restriction on the use of the material over

highways with less than 7.5m headroom was removed. It is now the material of choice for a wide range of

bridge decks.

It is also used in bridge and other large structural applications such as the New River Gorge Bridge, the newer

span of the Newburgh–Beacon Bridge, and the creation of the Australian Centre for Contemporary Art

(ACCA) and Mona.