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What is weathering steel?

What is weathering steel?
Update Time:2020-04-01

What is weathering steel?

Weathering steel is a low-alloy high-strength steel that has a small amount of alloying elements to make it have good corrosion resistance in the atmosphere. The weathering resistance of weathering steel is 2 to 8 times that of ordinary carbon steel, and the longer it is used, the more prominent the corrosion resistance. In addition to good weather resistance, weathering steel also has excellent mechanical and welding performance, and is widely used in railway vehicles, bridges and containers.

Weathering steel principle

The addition of phosphorus, copper, chromium, nickel and other trace elements to the steel will form a dense and highly adherent protective film on the surface of the steel, hinder the spread and development of rust, and protect the substrate below the rust layer to slow its corrosion rate. An amorphous spinel oxide layer of about 50 μm to 100 μm thick formed between the rust layer and the substrate is dense and has good adhesion to the base metal. The presence of this dense oxide film prevents oxygen and The infiltration of water into the steel substrate slows down the development of rust into the steel material and greatly improves the atmospheric corrosion resistance of the steel material. Weathering steel is a steel system that can be used thinner, barely used, or simplified coating, which makes the product prolonged corrosion resistance, save labor and reduce consumption, and upgrade. It is also a modern metallurgical new mechanism, new technology, and new process. Continuous development and innovative steel systems.

Weathering steel manufacturing process

Weathering steel generally adopts the process route of fine material into the furnace-smelting (converter, electric furnace-microalloying treatment-argon blowing-LF refining-low superheat continuous casting (feeding rare earth wire)-controlled rolling and cooling, etc. The scrap steel is added into the furnace together with the charge, and smelted according to the conventional process. After the steel is tapped, deoxidizers and alloys are added. After the molten steel is treated with argon blowing, the molten steel is cast. The rare earth element is added to the steel, the weathering steel is purified, and the content of inclusions is greatly reduced. (The rare earth element is an extremely active element and is a strong deoxidizer and desulfurizer, which mainly purifies the steel. The rare earth element can refine the crystal Grains, changing the state of inclusions in steel, reducing the number of harmful inclusions, reducing the source of corrosion, thereby improving the atmospheric corrosion resistance of steel)

Different weathering elements have different corrosion effects in different environments.For example, molybdenum is effective in reducing the corrosion rate of the industrial atmosphere, but the corrosion resistance of the marine atmosphere is not obvious. Therefore, depending on the corrosion environment, the weathering steel is special and special. The development of use, its composition system also changes accordingly, in order to improve the effectiveness and application efficiency of weathering elements. Special steel types such as seawater corrosion resistant steel, marine weathering resistant steel, acidic weathering resistant steel and heat-resistant zone weathering resistant steel are representative of this type of steel. Therefore, weathering steel should also develop in a diversified direction.

Surface treatment technology can also improve the performance of weathering steel. The development of a coating material that matches the weathering steel substrate will double its corrosion resistance.

Florence Tang
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