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.
Applications of Corten Steel
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. Examples of Corten structures include...
- The Angel of the North (UK)
- Matsunoyama Natural Science Museum (Japan)
- The Center for Contemporary Art (Australia)
The protective layer 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. Masteel are a stockist of Corten–B and Corten–A.
Corten Grades & Equivalents
The grades and equivalents of Corten steel are provided in the following table.
| Corten |
EN 10025-5:2004 |
| Corten A |
S355 J0WP |
| Corten B |
S355 J0W & S355 J2W |
Mechanical Properties and Thickness Ranges for Corten
The mechanical properties and thickness ranges of Corten steel are provided in the following table.
| |
Thickness (mm)
Strip Products |
Plate Products |
Yield strength
minimum |
Tensile stength
minimum |
Elongation
miniumum |
| Corten A |
2 – 12 |
6 – 12 |
345 |
485 |
20 |
| Corten B |
2 – 13 |
6 – 40 |
345 |
485 |
19 |
Chemical Composition of Corten Steel
The chemical composition of Corten steel is provided in the following table.
| |
Content, % (ladle analysis) |
| |
C
(max) |
Si |
Mn |
P |
S
(max) |
Al |
V |
Cu |
Cr |
Ni
(max) |
| Corten A |
0.12 |
0.25–0.75 |
0.20–0.50 |
0.07–0.15 |
0.030 |
0.015–0.06 |
– |
0.25–0.55 |
0.50–1.25 |
0.65 |
| Corten B |
0.19 |
0.30–0.65 |
0.80–1.25 |
0.035 max. |
0.030 |
0.020–0.06 |
0.02–0.10 |
0.25–0.40 |
0.40–0.65 |
0.40 |
Example Corrosion Allowances for Untreated Corten B
The example corrosion allowances for untreated Corten B steel are provided in the following table.
| Type of atmosphere |
Corrosion allowance to be added for one side of the
nominal thickness for each 10yr period of working life |
| |
First 10 year period mm |
Each following year period mm |
| Rural |
0.10 |
0.05 |
| Urban* |
0.20 |
0.05 |
| Industrial** |
0.20 |
0.10 |
| |
| * With the chief impurity in the air being sulphur dioxide |
| ** In addition to sulphur dioxide the air also contains chlorine. Also for locations in the immediate vicinity of salt water |
Formability of Corten Steel
The formability of Corten steel is provided in the following table.
| |
Thickness (mm) |
| (2)–3 |
(3)–4 |
(4)–5 |
(5)–6 |
(6)–7 |
(7)–8 |
(8)–10 |
(10)–12 |
(12)–14 |
(14)–16 |
(16)–18 |
(18)–20 |
| Smallest allowable internal bending radius mm |
| Corten A |
6 |
8 |
10 |
12 |
21 |
24 |
30 |
36 |
42 |
– |
– |
– |
| Corten B |
6 |
8 |
10 |
12 |
21 |
24 |
30 |
36 |
42 |
48 |
54 |
60 |
| Values apply to all forming directions |
Heat Treatment of Corten Steel
The heat treatment methods for Corten steel are provided in the following table
| Heat Treatment |
Temperature °C |
Treatment Time
Manner of cooling |
| Stress relieving |
500–600
(target 580) |
2 minutes / millimetre thickness, minimum 30 minutes
Slow cooling in the furnace |
| Normalising |
860–940
(target 910) |
1 minute / millimetre thickness, minimum 15 minutes
Free cooling in air atmosphere outside the oven |
This information has been sourced, reviewed and adapted from materials provided by Masteel UK Ltd.
For more information on this source, please visit Masteel UK Ltd