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What are the effects of carbon and silicon in the chemical elements of seamless steel pipes on the properties of steel

The effects of carbon and silicon in the chemical elements of seamless steel pipes on the properties of steel are as follows:
1. Carbon (C): Carbon is the main element second only to iron in the steel used for seamless steel pipes. As the carbon content increases, the strength of the steel increases, while the plasticity and toughness, especially the low-temperature impact toughness, decrease, while the weldability, Corrosion resistance, and cold bending performance are significantly reduced. Therefore, the carbon content of steel for seamless steel pipe structures should generally not exceed 0.22%, and for welded structures, it should be less than 0.2%. High carbon content will also reduce the atmospheric corrosion resistance of steel, and high-carbon steel in open-air stockyards will easily rust; in addition, carbon can increase the cold brittleness and aging sensitivity of steel.

2. Silicon (si): Silicon is added to the raw material of seamless steel pipe as a reducing agent and strong deoxidizer during the steelmaking process, so killed steel contains 0.15-0.30% silicon. If the silicon content in steel exceeds 0.50-0.60%, silicon becomes an alloying element. An appropriate amount of silicon can improve the strength of steel without significant adverse effects on plasticity, toughness, cold bending performance, and weldability. Silicon can significantly increase the elastic limit, yield point, and tensile strength of steel, so it is widely used in making spring steel.

Adding 1.0-1.2% silicon to quenched and tempered structural steel can increase the strength by 15-20%. Silicon is combined with molybdenum, tungsten, chromium, etc. to improve corrosion resistance and oxidation resistance, and can be used to make heat-resistant steel. Low-carbon steel containing 1-4% silicon has extremely high magnetic permeability and is used in the electrical industry to make silicon steel sheets. When the silicon content is too high, the plasticity, toughness, corrosion resistance, and weldability of the steel will be reduced.


Post time: May-13-2024