Weathering Steel

Also referred to as Atmospheric Corrosion Resistant Steel, this product is seen as an inexpensive and highly effective material to be used in structural applications which are exposed to the atmospheric elements.

The steel oxidises with pollutants in the air forming a thick layer of rust – this formation acts as a protective layer which prevents the steel from corroding. The layer constantly regenerates and forms over time.

Weathering steel is therefore classed as being a ‘self–protecting’ steel. In normal use the material does not need painting or other external treatment any kind.

Weather resistant steel can be used in a wide range of structural applications. It is a commonly used product in bridge construction because of the lack of maintenance costs. It is also popular in modern architecture where the aesthetically pleasing finish is in great demand for sculptural buildings and fascias.

Masteel offers an extensive range of weathering steel with the following benefits…

• major stockholding
• global shipping
• variety of plate widths
• extensive range of thicknesses
• quick turnaround
• accurate ‘in-house’ cutting and profiling service
• high quality steel from major European steel mills

Corten steel (often referred to as Cor–Ten) is a weather resistant steel which could more accurately be termed as an “Atmospheric Corrosion Resistant Steel”.

It is a copper chromium alloy steel – this alloy displays a greater level of resistance to atmospheric weathering when compared to other unalloyed steels. It’s chemical composition promotes the early formation of an adhering protective layer of rust when exposed to the elements.

Aesthetically pleasing to the eye, this finish has become popular with many high profile architects and has been specified and used in a variety of applications in including building fascias, architectural sculptures and bridges.

The protective layer of Corten constantly develops and regenerates over time, reacting to the pollutants in the atmosphere. Consideration should be made with regard to the thicknesses used especially when the material is utilised for structural rather than solely cosmetic purposes.

The benefits of such a steel are immediately obvious – a self–protecting steel is economic, long lasting and easily recyclable.

Corten A – a weather resistant steel created by alloying copper, chromium and nickel. In addition to this, Corten A has added phosphorous which makes the material best suited for gas flue applications and for aesthetic facias The material is not recommended in heavy load bearing applications – in this case Corten B or S355J2W should be considered.

The top layer of the material reacts with atmospheric elements to form a rust coloured protective layer which not only makes the steel virtually maintenance free but also provides a pleasing and consistent finish.

Grades & Equivalents

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Mechanical Properties

Corten B – a weather resistant steel which is better suited for heavy and load bearing structures.

The material forms its own protective layer when exposed to atmospheric elements. Essentially, the top layer corrodes which then protects the steel beneath it. The natural finish does not normally require any form of maintenance such as painting, which makes the material a highly cost effective alternative to other structural steels.

Painting and maintenance will be required if the structure is is continually wet as a protective layer will not form. An good example is where the base of the structure meets with the ground or is partially submerged.

Please refer to the technical specifications below.

Grades & Equivalents

Mechanical Properties

S355J0WP is a structural weathering steel which is also referred to as atmospheric corrosion resistant steel. The main alloying elements are chromium nickel and copper with added phosphorous which gives it excellent self protecting qualities. As the steel reacts with elements in the atmosphere, the material forms a layer of rust over time which in essence protects the steel from corrosion.

S355J0WP (which is an equivalent grade to Corten A) provides a long lasting and economic structural steel solution for use in applications such as steel bridges stack gas applications and in steel sculptured buildings due to the material’s aesthetically pleasing finish.

Grades & Equivalents

Mechanical Properties of S355JOWP

Like S355J0WP, S355J0W is a weathering steel and is an equivalent to Corten B.

As the material rusts when exposed to atmospheric elements, the material builds its own protective layer which prevents the steel from further oxidation. Therefore S355J0W, like all weathering steels, offers excellent, cost effective protection against atmospheric conditions without the need for painting or external treatment.

S355J0WP tends to be used for structures which use thinner materials.

Grades & Equivalents

Mechanical Properties of S355JOW