A588GrB Steel Plate Analysis of Chemical Composition

1.A588GrB steel plate Introduction

A588GrB steel plate is a high weathering bridge structural steel plate, which belongs to the American standard steel plate and implements the American standard ASTM standard. When the A588GrB steel plate is rolled, a protective layer is formed on the surface of the metal matrix through the alloying of Cu, P, Cr, N, etc., so that the A588GrB steel plate has high atmospheric corrosion resistance.

2. Chemical composition of A588GrB steel plate (melting analysis %)

C: not more than 0.20, Mn: 0.75-1.25, P not more than 0.04, S not more than 0.05, Si: 0.15-0.50, Ni not more than 0.50, Cr: 0.40-0.70, Cu: 0.20-0.40, V: 0.01-0.1

The influence of the content of the five elements on the properties of the steel plate:

a. Carbon (C): The carbon content in the steel increases, the yield point and tensile strength increase, but the ductility and impact decrease. When the carbon content exceeds 0.23%, the welding performance of the steel deteriorates, so it is used for welding. Low alloy structural steel, the carbon content generally does not exceed 0.20%. High carbon content will also reduce the atmospheric corrosion resistance of steel, and high carbon steel in the open stock yard is easy to rust; in addition, carbon can increase the cold brittleness and aging sensitivity of steel.

b. Silicon (Si): In the steelmaking process, silicon is added as a reducing agent and a deoxidizer, so the killed steel contains 0.15-0.30% silicon. If the silicon content in the steel exceeds 0.50-0.60%, silicon is considered an alloying element. Silicon can significantly improve the elastic limit, yield point and tensile strength of steel, so it is widely used as spring steel. Adding 1.0-1.2% silicon to quenched and tempered structural steel can increase the strength by 15-20%. The combination of silicon and molybdenum, tungsten, chromium, etc. can improve corrosion resistance and oxidation resistance, and can manufacture heat-resistant steel. Low carbon steel with silicon content of 1-4% has extremely high magnetic permeability, and is used in electrical industry to make silicon steel sheets. An increase in the amount of silicon will reduce the weldability of the steel.

c. Manganese (Mn): In the process of steelmaking, manganese is a good deoxidizer and desulfurizer. Generally, steel contains 0.30-0.50% of manganese. When more than 0.70% is added to carbon steel, it is considered "manganese steel". Compared with ordinary steel, it not only has sufficient toughness, but also has higher strength and hardness, which can improve the hardenability of steel and improve the hot working performance of steel. For example, the yield point of 16Mn steel is 40% higher than that of A3. Steel containing 11-14% manganese has extremely high wear resistance and is used for excavator buckets, ball mill lining plates, etc. The increase of manganese content weakens the corrosion resistance of steel and reduces the welding performance.

d. Phosphorus (P): In general, phosphorus is a harmful element in steel, which increases the cold brittleness of steel, deteriorates welding performance, reduces plasticity, and deteriorates cold bending performance. Therefore, the phosphorus content in steel is usually required to be less than 0.045%, and the requirements for high-quality steel are lower.

e. Sulfur (S): Sulfur is also a harmful element under normal circumstances. It makes the steel hot brittle, reduces the ductility and toughness of the steel, and causes cracks during forging and rolling. Sulfur is also detrimental to weldability, reducing corrosion resistance. Therefore, the sulfur content is usually required to be less than 0.055%, and the high-quality steel is required to be less than 0.040%. Adding 0.08-0.20% sulfur to steel can improve machinability, usually called free-cutting steel.