Topics covered
Overview
Applications of Corten Steel
Corten Grades &
Equivalents
Mechanical Properties and Thickness Ranges for
Corten
Chemical Composition of Corten Steel
Example Corrosion Allowances for
Untreated Corten B
Formability of Corten Steel
Heat Treatment of Corten
Steel
Overview
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 |
Source: Masteel
For more information on this source, please visit Masteel