What is COR-TEN Steel? Know Corten Steel Features, Types , Applications & Uses

by AMC

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Posted on November 24, 2022 at 10:20 AM

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What is Corten Steel?

Corten Steel (also known as weathered steel) is a category of steel alloys that are commonly used in outdoor construction. Corten Steel was designed to eliminate the need for painting, and if left outside and exposed to the elements, it will rust in a matter of months.

Cor-ten Steel Features

Weather Resistance : COR-TEN doesn't rust easily, so it doesn't need to be painted. Unpainted applications not only provide the economic benefit of lowering repainting costs, but they also provide aesthetic benefits due to the relaxing tone of the protective rust. While weather resistance varies depending on the product grade and application environment, COR-TEN has roughly 4-8 times the weather resistance of ordinary steel.

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Paint Durability : COR-TEN can be painted just like regular steel. Also, even if there is a problem with the paint, COR-TEN stops the rust from spreading, which makes the paint last longer and saves money on repainting.

Weldability : Trace amounts of alloying elements like copper (Cu) and chromate (Cr) are added to COR-TEN to make it resistant to the weather, but the carbon content is lowered to make it easy to weld. So, COR-TEN can be welded by hand, with a gas shield, or with an arc that is submerged in a liquid. Thin-gauge COR-TEN can also be joined with spot welding.

Workability : COR-TEN is just as easy to work with as regular steels of the same strength. It can be bent, shaped, and cut with gas.

Reliability : Since "COR-TEN" started being sold in 1959, more than 2.6 million tonnes of it have been made.

Cor-ten Steel Application Example

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Uses of Cor-ten Steel

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1.Garden and Landscape Design:From Planter boxes to landscape edging, there are many ways to shape and decorate an outdoor space with weathering steel. In fact, The Wall Street Journal identified cor-ten as a top trend in landscape design.

2.Roofing and siding: Weathering steel corrugated and profile panels, which are made from ASTM A606-4 and A588, are often used to build roofs and building walls. For example, the office building for Amardeep Steel was made of cold-rolled Corten steel. ASTM A606-4 corrugated rib panels were used to make the building's exterior walls.

3.Sign posts:

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Because of the protective patina, Corten steel sign posts are made to last 30 years longer than regular steel posts. Plus, they look great in the outdoors. Sign posts made of steel that doesn't rust are often used for traffic signs and to mark the end of vineyard rows.

4.Security solutions Corten steel is ideal for security applications such as gates, fences, and bollards. The rusty patina that the steel develops over time mixes nicely in outdoor places such as playgrounds, parks, farms, and vineyards, as it does in other weathering steel applications.

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5.Outdoor sculptures: Weathering steel has grown in popularity for usage in outdoor sculptures. Sculptors use weathering steel's corrosion resistance, availability, fabricability, and look to create a variety of eye-catching and appealing works of art.

COR-TEN Steel Specifications

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COR-TEN Steel Chemical Composition

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Types of COR-TEN Steels

Normally, two types of weathering steel are produced. These are also known as COR-TEN A and COR-TEN B. The primary distinction between the varieties is the quantity of P alloyed in the composition. COR-TEN A is normally manufactured as a sheet or coil and is used in cladding and ductwork.COR-TEN B is more often manufactured as a plate, structural segment, or tube.

The weather resistance of COR-TEN steels is based on the oxide coating, or patina, that forms on the surface of the steel and is dense and practically impenetrable to O2 as a result of the alloying elements. If the surface is alternately wet and dry, the patina forms about 18 to 36 months under normal weather circumstances. The patina is initially a reddish brown color, but it darkens over time.

Patina occurs faster and is darker in color in industrial surroundings than in rural areas. Chlorides in maritime conditions inhibit the production of the protective patina and can interfere with the intrinsic behavior of COR-TEN steel. As a result, COR-TEN steel should not be utilized near the sea or in places where the air has a significant concentration of chlorides. In the case of open-air constructions, the slow corrosion rate is accounted for by adding corrosion allowance to the nominal thickness.

Advantages of COR-TEN Steels

COR-TEN steel is resistant to air corrosion, allowing it to be utilized without paint in many structural / architectural applications such as bridges, some open-frame buildings, transmission poles, and sculptures. COR-TEN steel also possesses high temperature properties, making it an excellent material for various flues, chimneys, and high temperature ducting. COR-TEN steel's corrosion resistance gives it significant benefits over other metals for structures exposed to the elements. These are provided below.

1. Low maintenance COR-TEN steel is appropriate for bridges and other structures with difficult or dangerous access and where future disruption must be kept to a minimum. The only maintenance required to maintain the structure's continued performance is inspection and cleaning.
2. Start up cost benefits The savings from not having to use any protective coatings or paints more than offsets the additional material cost of the COR-TEN steel. Weathering steels, for example, are around 5% less expensive than traditional painted steel alternatives in bridges.
3. Project life cost benefits Nominal maintenance requirements of COR-TEN steel structures significantly reduce maintenance operations costs and potential indirect costs of traffic delays in the case of bridges.
4. Construction Speed Because COR-TEN steels do not require painting on-site or in the fabrication shop, construction activity is expedited.
5. Aesthetic appeal The appealing appearance of mature COR-TEN steel frequently combines well with the surroundings. With age, its appearance changes and improves.
6. Environmental benefits Use of COR-TEN steel eliminates the need for blast cleaning and VOC laden paints.
7. High temperature benefits Steel can oxidize at temperatures above 400 degrees Celsius. The use of COR-TEN steels can help to reduce this. COR-TEN steels develop a protective patina at temperatures above 400 degrees Celsius. A typical improvement is a temperature increase of 50 degrees Celsius over the comparable loss in cc-Mn steels. Above 450 degrees Celsius, COR-TEN steels are not acceptable for use in substantial load bearing parts.

Corrosion

Corrosion is the chemical or electrochemical degradation of construction materials caused by external factors. Corrosion is a property of all materials. In the case of steel, this leads to rusting. Steel's rusting behavior is determined by its chemical makeup, the environment, structural concerns, and a proper building design. Weathering steels are alloyed with minor amounts of Cr, Ni, Cu, and P to control corrosion behavior. Figure 2 depicts a comparison of the corrosion rates of COR-TEN steel and plain C steel.

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Fig 2 Comparison of the corrosion rates of COR-TEN steels and plain C steels
The environment also has a considerable influence on the corrosion behaviour of the steels. Corrosion rates of COR-TEN steels in different environments are shown in Fig 3.

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Fig 3 Corrosion rates of COR-TEN steels When the surface of COR-TEN steel is exposed to outdoor air, the O2 and moisture in the air produce a compact oxide layer, patina, developing on the surface, thus preventing the further propagation of corrosion. Fig 4 illustrates the difference between the corrosion rates of general structural steels and COR-TEN steels. There is difference between the corrosion rates of general structural steel and COR-TEN steel. Cyclical corrosion loss represents the change in weight/ reduction of thickness which occurs when a protective oxide layer fails to develop. The corrosion cycle of steel consists of steel oxidizes – the rust layer protects – wears off – the steel surface oxidizes again, etc. In COR-TEN steel, the initial corrosion rate remains high until the protective oxide layer prevents further oxidation. The actual corrosion loss is low.

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Fig 4 Comparison of corrosion rates of COR-TEN steel and structural steel Forming COR-TEN steel, like conventional structural steels of the equivalent grades, can be cold formed. Successful shaping necessitates good workshop technology from the steel product's manufacturer. Worn tools, insufficient lubrication, plate surface flaws, and cutting burrs can all degrade quality. Shot blasting can also be harmful.
Bending with the axis transverse to the principal rolling direction is desirable for strip rolled items. Exacting forming procedures are easier to carry out either by warm forming at temperatures below 600 degrees Celsius or by hot forming at temperatures ranging from 800 degrees Celsius to 1050 degrees Celsius.

Can Corten Steel be Welded?

Welding on corten steel is identical to welding on low carbon steel. The sole precaution welders must take is with regard to the filler or electrode, which differs from mild steel. When it comes to welding electrodes for weathering steel, AWS E7018 is the best option. The electrode used is determined by two factors: needed strength and code requirements.

Corten Products & Applications

Acoustical Panels	Buses	Door (Water-cooled)	Open Bridge Deck	Ski-tow Towers	Tanks
Agricultural Equipment	Cable Guards	Exhaust Fans - Industrial	Outdoor Signboard Supports	Snow Plow Parts	Towboats
Air Conditioning Equipment	Cable Trays	Flash Chamber - Evaporators	Outside Storage Racks	Spray Dryers	Traffic Signal boxes/Lights
Airport Runway Lights	Cladding	Floor Parts	Pipe - Structural	Stack/Stacks Liners	Transformer Shells
Air Pre heaters	Concrete Forms	Frame Expansion Joints	Pole Line Hardware	Stack Regulators	Transmission Towers
Amusement Park Rides	Containers	Door (Water-cooled)	Pollution Control Equipment	Stairs and Handrails	Trash barrels
Auto Transport Loading Ramps	Conveyors	Door (Water-cooled)	Pontoons/Pontoon Grating	Steam-generating Apparatus	Trenching Machinery
Baghouse Dust Collectors	Dams and Locks	Exhaust Fans - Industrial	Pumps and Pump Parts	Storage Containers	Trolley Cars
Bins	Derricks	Flash Chamber - Evaporators	Railroad Rolling Stock	Stove Parts	Trucks
Blast Plates	Ductwork	Floor Parts	Open Bridge Deck	Structural Conveyor Tubes	Tubing - Mechanical
Blowers	Electric Dust Precipitators	Ladders	Railroad Signal Towers and Boxes	Tanks	Ventilation Louvers
Bolts and Nuts	Earth-moving Equipments	Light Standards	Rakes - Classifier	Towboats	Wheelbarrows

According To Following Standard & Specifications:

EN 10155	NFA 35-502	SEW 087	UNI	BS 4360	JIS G3114	ASTM	INDIAN STANDARD	OTHERS
S235J2W	E24 W 4	WTSt 37-3	Fe 360 DK1	WR 50 A	SMA 50 AW	Weathering Steel-A	IRSM41-97	09CUPCRNI-A
S355J0WP	E36 WA 3	WTSt 52-3	Fe 510 C1K1	WR 50 B	SMA 50 CP	Weathering Steel-B	SAILCOR	9CRNICUP234
S355J2WP	E36 WA 4		Fe 510 D1K1	WR 50 C		A242 Type1		10HNAP,
S355J0W	E36 WB 3		Fe 510 C2K1			A 588 Gr.B		10XHAP
S355J2G1W	E36 WB 4		Fe 510 D2k1			A 588 Gr. A		10 KHNDP
S355J2G2W						A 588 Gr. C		JIS G 3125 SPA-H
S355K2G1W						A 709 Gr. 50 W		15217
								17G1S

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