Weathering steel
Weathering steel (also known by the trademark COR-TEN steel) is a form of high-strength, low alloy steel originally developed in the 1930's by United States Steel. It is a steel alloy, chemically composed to form a stable rust-like appearance that can resist corrosion and abrasion, by forming a protective surface layer, or patina.
The protective layer’s increased resistance is produced by the alloying elements and their particular distribution and concentration. When subjected to the influence of the weather, the protective surface layer continuously develops and regenerates, allowing the rust to form.
Weathering steel is often used in external sculptures, the most iconic of which is the Angel of the North in Gateshead. It can be used in bridges and other large structural applications, such as the New River Gorge Bridge, and it is becoming an increasingly popular design choice for buildings, often used alongside materials such as glass and terracotta. An example of such a building is the distinctive Broadcasting Tower in Leeds (see top image).
The advantages of weathering steel are that because it is already weathered and ‘rusted’, there are very low maintenance costs, it can be installed easily, and the need for a protective paint system is removed. Studies have found that bridges fabricated from unpainted weathering steel can achieve a design life of 120 years with only nominal maintenance, due to the low corrosion rate.
However, there are several challenges to weathering steel. It is unsuitable for use in marine or coastal environments, and in humid subtropical climates the patina may continue to corrode instead of stabilising into a protective layer. In addition, interface details require careful design as run-off water from wet rusted steel may negatively impact on other materials, such as staining glass. This is a particular problem in the first years after installation.
Special welding techniques or materials may be needed to ensure that weld-points weather at the same rate as the other materials.
[edit] Related articles on Designing Buildings
Featured articles and news
Industry leader Steve Murray takes on role.
An abundant and versatile building material.
How overheating complicates ending gas in the UK.
600,000 heat pump installations targeted per year by 2028.
Cost planning, control and related articles on DB.
Helping prevent those unwanted outcomes.
ICE debate Public transport - post pandemic.
How has transport changed due to Covid-19 ?
Cross-ventilation in buildings. Do you have it ?
Will you need it ? after June 15 and the new Part O ?
Share your knowledge with the industry.
Create an account and write the first of many articles.
The green jobs delivery group.
CIAT commentary after the first meeting.
Liverpool's world heritage site status
Who is to blame?
Research recommends focussing on portfolio success rather than project success.
ICE and BSI launch revised PAS 128 standard.
The revised standard for mapping underground utilities.
Launching the UK net zero carbon buildings standard.
Cross-industry steering group seeks support in delivery.