American Standard A588 Weathering Steel Chemical Composition Analysis and Application

A588 is the grade of American standard weathering steel. Weathering steel refers to low-alloy steel that has good corrosion resistance in the atmosphere by adding a small amount of alloying elements. Weathering steel is widely used abroad, and related research and development are also being carried out in China. The product has been developed and put into use. In order to meet the market demand and adjust the product structure, the development of new products has been intensified, and the American Standard weathering steel A588 series has been successfully developed: A588GrA, A588GrB, and A588GrC.

A588 steel plate series Chemical composition: (%)

Carbon content C: ≤0.19
Silicon content Si: 0.30~0.65
Manganese content Mn: 0.8~1.25
Phosphorus content P: ≤0.040
Sulfur content S: ≤0.050
Vanadium content V: 0.02~0.10
Chromium content Cr: 0.40~0.65
Nickel content Ni: ≤0.40
Copper content Cu: 0.25~0.40

Adding a small amount of alloying elements copper, chromium, and nickel to ordinary low-alloy steel can improve the corrosion resistance of the steel plate, and its atmospheric corrosion resistance is 2 to 8 times that of ordinary carbon steel, and the longer the use time, the more prominent the corrosion resistance .

1. Cu is the most important and most commonly used alloying element in atmospheric corrosion-resistant steels to improve atmospheric corrosion resistance, because in the process of atmospheric corrosion, Cu acts as an active cathode, which can passivate the anode of the steel, thereby Reduces the corrosion rate of steel. However, due to the selective oxidation of Cu, Cu added alone will be enriched on the surface of the steel, which will easily lead to hot cracks in the production process of Cu-containing steel. This is because Cu delays the transformation of austenite. With the increase of Cu content, the steel The third brittle zone becomes wider and the brittle temperature range increases.

2. Adding Ni to the steel can increase the plasticity and minimum area reduction rate of the third brittle zone, and improve the high temperature plasticity of the steel. Ni is also an effective element for atmospheric corrosion resistance, and when Ni and Cu are used in combination, the effect of improving atmospheric corrosion resistance is better. In actual production, copper brittleness can be prevented by adding Ni higher than 1/2 Cu content. Cr can form a dense oxide film on the surface of steel, improve the passivation ability of steel, and slow down the growth rate of rust layer.

3. When Cu, Ni and Cr are added at the same time, its corrosion resistance is particularly obvious. Combined with the requirements of ASTM A588/A588M-2003 standard for chemical composition, the designed smelting composition takes measures to improve the purity of molten steel, such as controlling the content, shape and size of inclusions in the steel, and improving the corrosion resistance of steel.

4. As the strength level of weathering steel increases, the requirements for inclusions also increase. According to relevant data, when producing weathering steel, T (O) < 30 × 10, (H) < 2 × 10, (N )<50×10, (S)<200×10.

Application range of A588 steel plate:

A588GrA, A588GrB, A588GrC These steels are used in welding, engineering machinery, riveting and bolting structures, but are mainly used in welded bridges and buildings where weight reduction or life extension is required. The atmospheric corrosion resistance of this steel is significantly better than copper-containing or copper-free carbon structural steel under most environmental conditions.

When fully exposed to the atmosphere, this steel is suitable for many occasions in the bare (uncoated) state, such as: drilling rigs for mines and various engineering constructions, electric shovels, electric wheel dump trucks, mining vehicles, Excavators, loaders, bulldozers, various types of cranes, coal mine hydraulic supports and other mechanical equipment and other structural parts, or for construction in harsh weather, or for the construction of waiting halls, steel structure welding.