CORTEN LIFE SPAN INFORMATION

Life Span

Weathering steel alloys, are often refereed to as Corten,

Corten steel, was a steel alloy that was first developed in 1933.

Weathering steel ASTM A606-4 often sold as Corten, develops a protective oxide film.

Unlike raw steel, Cor-Ten steel is corrosion resistant due to its alloy composition.

This oxide bonds with the base metal and continues to corrode over time at a much slower rate.

Variations in colour, hue and texture should be expected; these variations are not flaws.

Technical Specifications

Details on Corten weathering steel.

Area Nominal thickness lost for each 10yr period

Rural First 10yr period (1/1000th inch)

Urban * Subsequent 10yrs (1/1000th inch)

Industrial ** Electrolytic Isolation

* With the chief impurity in the air being sulphur dioxide Galvanized Steel

** In addition to sulphur dioxide the air also contains chlorine Zinc flashings should not be in direct contact with corten

Increased thickness = increased life span

Adding 0.04 inch to the exposed face of corten steel adds approx 100yrs to life span

Always check the thickness and grade of steel being purchased

Low cost sellers often do not publish the steel thickness or grade (chemical composition) being offered.

The life expectancy of weathering steel depends on the following

1/ the environment

2/ the steel has repeated wet/dry cycles to form and maintain the protective oxide coating

3/ the thickness of the steel specified

For example

In urban areas of moderate pollution, and low salinity, over a 50yr period one may expect 20 thou of corten steel to corrode away

For an exposed steel beam this would mean adding 40 thou to the flange thickness at year zero, to ensure that at year 50 the flange thickness is still at the design thickness.

For longer required life spans and more corrosive environments additional thickness would be added.

For structural elements the requirement may be 50yrs

The weathering process is not linear, with approx 80% of the decay occurring in the first years of life, most specifiers therefore tend to use steel that is 20 thou to 40 thou thicker than required to allow for unexpected corrosion.

In applications where the corten steel can not maintain the wet/dry cycles to establish the protective oxide, such the inside of planters. It is recommended to seal inside/unseen steel with a bitumen damp proof membrane such as Henry 101 Non-fibered Foundation Coating or equivalent available from Home Depot

There is no warranty with unprotected raw steel, the specifier matches the expected environment conditions and the selected thickness of steel, to arrive at a prediction of the expected life span. Domestic landscaping applications may be happy with an expected life span of 30yrs plus, while bridge engineers often require 120yrs plus

Q355NH Weathering steel

Chemical composition(%)

C:≤0.16 Si≤0.5 Mn:0.5-1.5 P≤0.03 Cr:0.4-0.8 Cu:0.25-0.55

Mechanical property

Yield strength/Mpa:≥355 Tensile strength/Mpa:490-630 Elongation/%≥22

EXPLORE OUR PAGES

Corten Garden Edging, Fences, Firepits, Planters, Retaining Walls and Tree Surrounds. View our full range to find the perfect Corten products.