COR-TEN® is a trademarked name owned by U.S. Steel.
COR-TEN® steel is becoming more popular by roll formed product end-users. Its unique look and naturally oxidizing finish make it especially desirable for many architectural projects. Weathering steel, best-known under the trademark COR-TEN® steel, is a group of steel alloys which were developed to obviate the need for painting, and form a stable rust-like appearance if exposed to the weather for several years. Weathering steel has increased resistance to atmospheric corrosion when compared to other steels. COR-TEN® resists the corrosive effects of rain, snow, ice, fog, and other meteorological conditions by forming a coating of dark brown oxidation over the metal, which inhibits deeper penetration and negates the need for painting and costly rust-prevention maintenance over the years. In simple terms the steel is allowed to rust and that rust forms a protective coating that slows the rate of future corrosion.
CAN I BUY COR-TEN®?
No, COR-TEN® is not available. What is available is steel in an A606-4 or an A588 finish. If somebody tells you that they are supplying you COR-TEN® they are almost certainly unaware of their own product. Simply ask them if their steel was purchased from U.S. Steel. If the answer is ” No ” or ” I don’t know ” it’s almost certainly NOT COR-TEN®. When someone needs COR-TEN® they are normally referring to A606 Type 4 or A588. If you want COR-TEN® this will be the best available option. Weathering steels, such as ASTM A588, A242, A606 and COR-TEN® exhibit superior corrosion resistance over regular carbon steel as a result of the development of a protective oxide film on the metals surface which slows down further corrosion. A606-4 steel is available in metal roofing/siding panels, standing seam panels, flat sheets, and coil form.
WHAT IS A606 TYPE 4?
The original COR-TEN® received the standard designation A 242 (“COR-TEN® A”) from the ASTM International standards group. Newer ASTM grades are A 588 (“COR-TEN® B”) and A606 for thin sheet. All alloys are in common production and use.
CLIMATES NOT TO USE COR-TEN®:
COR-TEN® steel requires alternating wet and dry cycles to form a properly adhered protective layer. Areas that have salt laden air, high rainfall, humidity, or persistent fog are typically not the proper environment for COR-TEN®.
DOES IT COME PRE-RUSTED?
A606-4 and A588 steel arrives UNRUSTED and will rust with naturally exposure to the weather.
WHAT DO I HAVE TO DO TO GET COR-TEN® TO RUST?
Nothing. This material will rust on its own if left exposed to the weather. Getting the material wet will increase the speed in which it rust.
WILL COR-TEN® CONTINUE TO RUST?
Weathering Steel never completely stops rusting. The weathering process occurs after the panel is installed. It eventually decreases and from that point on the finish acts as a protective coating for the base metal.
This protective coating essentially stops the corrosion. Laboratory analysis of the rust film have shown that the alloying elements in the steel, particularly copper, chromium, and nickel produced insoluble compounds that clogged the pores at the rust/steel interface, thereby ending the regeneration.
WILL THE RUST STAIN THE SURROUNDING AREAS?
Yes, rust runoff will likely stain the surrounding areas.
IS THERE A WARRANTY?
There are no warranties for A606-4 or A588 Steel.
DISSIMILAR METALS AND COR-TEN®:
In general do NOT use dissimilar metals with COR-TEN®.
Galvanized, galvalume®®, and zinc should NOT come into contact with COR-TEN®.
Stainless steel is compatible with COR-TEN®.
WHAT ABOUT COLOR MATCHING THE SCREWS?
Screws are furnished in a Stainless Steel/Painted Koko Brown
IS THERE A SPECIAL TYPE OF UNDERLAYMENT FOR USE WITH COR-TEN®?
It is recommended to use a high temperature underlayment. We do not sell underlayment. Contact an expert in underlayment for further details.