Steel is the most widely used and widely used metal material in economic construction, occupying an important position in modern industrial and agricultural production.

Carbon steel: Iron carbon alloys with a carbon content between 0.0218% and 2.11% are called carbon steel, abbreviated as carbon steel.

Alloy steel: Iron based alloys that intentionally add one or more alloying elements to carbon steel to improve its usability and process performance are called alloy steel.

In addition to iron, carbon, and alloy elements, there are also elements such as silicon, manganese, sulfur, phosphorus, nitrogen, hydrogen, and oxygen brought in with pig iron, deoxidizers, and fuel during steelmaking.

There are various classification methods for steel, and the main methods are as follows:

1、 Variety of steel

For the convenience of procurement, ordering, and management, China currently divides steel into four categories based on its appearance: profiles, plates, pipes, and metal products, with a total of sixteen varieties:

1. Profile

Rail, profile steel (round steel, square steel, flat steel, hexagonal steel, I-beam, channel steel, angle steel, and threaded steel, etc.), wire rod (round steel and wire rod with a diameter of 5-10 millimeters), etc.

2. Plate

Thin steel plate: steel plates with a thickness of 4 millimeters or less;

Thick steel plate: steel plate with a thickness greater than 4 millimeters; It can also be divided into medium plates (thickness greater than 4mm but less than 20mm), thick plates (thickness greater than 20mm but less than 60mm), and extra thick plates (thickness greater than 60mm);

Steel strip: also known as strip steel, it is actually a thin steel plate that is long and narrow and supplied in coils;

Electrical silicon steel sheet: also known as silicon steel sheet or silicon steel sheet.

3. Pipe materials

Seamless steel pipe: a seamless steel pipe produced by methods such as hot rolling, hot rolling cold drawing, or extrusion, with no seams on the pipe wall;

Welded steel pipe: a steel pipe made by bending a steel plate or strip into shape and then welding it.

4. Metal products: including steel wires, wire ropes, steel strands, etc.

2、 Classification of Steel

There are various types of steel, and in order to facilitate production, use, and research, steel can be classified based on chemical composition, metallurgical quality, and usage.

1. Classify according to chemical composition. There are two major categories: carbon steel and alloy steel.

Carbon steel: Low carbon steel (Wc<0.25%), medium carbon steel (Wc=0.25%~0.60%), and high carbon steel (Wc>0.6%)

Alloy steel: divided into low alloy steel (Me<5%), medium alloy steel (Me=5-10%), and high alloy steel (Me>10%) based on the total amount of alloying elements in the steel (Me%).

According to the type of alloy elements, it can be divided into manganese steel, chromium steel, boron steel, chromium nickel steel, silicon manganese steel, etc.

2. Classified by metallurgical quality. According to the amount of harmful impurities such as sulfur and phosphorus contained in steel, it can be divided into:

Ordinary steel: S% ≤ 0.055%, P% ≤ 0.045%

High quality steel: S%, P% ≤ 0.040%

High quality steel: S% ≤ 0.030%, P% ≤ 0.035%

In addition, according to the degree of deoxidation during smelting, steel can be divided into three categories: boiling steel (partially deoxidized), killed steel (partially deoxidized), and semi killed steel.