How is steel classified

Steel is the most widely used metal material in industry. According to different requirements, its classification methods are different.

1. Classification by steel smelting method
According to the type of steelmaking furnace, the steel can be divided into open hearth steel, converter steel and electric furnace steel.
According to the degree of deoxidization and pouring system, the steel can be divided into boiling steel, killed steel and semi killed steel.

2. Classification according to the content of chemical elements in steel
According to the chemical composition of steel, it can be divided into carbon steel and alloy steel.
In carbon steel, if the carbon content is less than 0.25, it is called low carbon steel; if the carbon content is greater than 0.25, but less than 0.60, it is called medium carbon steel; if the carbon content is greater than 0.60, it is called high carbon steel. In alloy steel, if the total content of alloy elements is less than 5, it is called low alloy steel; if the total content of alloy elements is between 5-10, it is called medium alloy steel; if the total content of alloy elements is more than 10, it is called high alloy steel.

3. Classification by steel quality
According to the quality of steel, it can be divided into three types: ordinary steel, high-quality steel and high-quality steel.
In general steel, the content of sulfur and phosphorus is relatively high, which is generally no more than 0.05; in high-quality steel, the content of sulfur and phosphorus is relatively low, such as 20# carbon steel, which is no more than 0.04; in high-quality steel, the content of sulfur and phosphorus is the highest, which is no more than 0.035, with the letter "A" after the steel number, indicating high-quality steel.

4. Classification by use of steel
According to the use of steel, steel can be divided into: structural steel, tool steel, heat-resistant steel, low-temperature steel, stainless steel, etc.