Weathering steel products are commonly used in the painted condition for constructions such as steel boats and freight containers for sea transport. In continuous contact with water, the corrosion rate hardly differs from that of general structural steels, but the paint life on weathering steels can be up to twice as long. This is because the propagation of corrosion under local damage on painted surfaces is markedly slower than on ordinary steel. In this way, the appearance of painted structures remains trim much longer and the lifetime cost of shot blasting and repainting is halved.
NES Architectural oers weathering steels to both Standard EN 10155 and under the brand name COR-TEN. The steel grades S355JOWP, S355J2JOWP and COR-TEN A have the best weathering properties. Because of the phosphorus used as an alloying element, however, the impact strength of these steel grades is lower than that of other weathering steels. These weathering steels are best suited for sheet steel structures that are not under the risk of brittle fracture. Typical applications for weathering structural steels include
• external wall claddings of buildings, weather strips
• chimneys and other structures under ue gas conditions
• transport tanks
• freight containers
• heat exchangers
• similar other steel structures.
When the risk of brittle fracture has to be taken into consideration in the design because of high material thickness, low service temperature or for other reasons, it is better to choose another EN 10155 steel or COR-TEN B. Then the impact strength requirements for hot rolled steel can be agreed upon as for general structural steels. At temperatures above 540°C, S355J0WP, S355J2WP, COR-TEN A and COR-TEN B have a clearly higher resistance to scaling than general structural steels. Research has shown that the resistance to scaling is rather good at a stable temperature up to 650°C, but reduces, if the temperature keeps changing considerably. In the latter case, it is recommended that the peak temperature should be 540°C. In terms of resistance to scaling at high temperatures, the best weathering steel is COR-TEN High Temp.