Classification of carbon steel, common grade of carbon steel

Classification of carbon steel, common grade of carbon steel

Carbon steel is an iron carbon alloy with carbon content ranging from 0.0218% to 2.11%. Also known as carbon steel. It also contains small amounts of silicon, manganese, sulfur and phosphorus. The higher the carbon content of general carbon steel, the greater the hardness, the higher the strength, but the lower the plasticity.

1. According to carbon content:

Low carbon steel, medium carbon steel, high carbon steel.

(1) The carbon content of low carbon steel is generally less than 0.25%. Its strength is relatively low, but the plasticity, toughness and welding performance are better, easy to press. Therefore, commonly used to make a variety of plates, can be used to make a variety of stamping parts and containers. This kind of steel is also often used to manufacture a variety of carburized parts. After carburizing and quenching, the steel surface has high hardness and good wear resistance, while the heart maintains a certain strength and toughness. Can be used to make impact load bearing parts and wear resistant parts, such as gears, short shafts, dowel, etc. Therefore, this kind of steel is also called surface hardening steel or carburizing steel.

(2) carbon steel steel carbon content is generally between 0.25~0.6%. This kind of steel has high strength but low plasticity and toughness. This kind of steel in use is generally after heat treatment and tempering treatment, after tempering treatment, can get high strength and good toughness. It can be used to manufacture all kinds of shafts, rods, sleeves, pins, bolts, nuts, etc. If the surface quenching after conditioning, can make the surface hard and wear-resistant, can manufacture a variety of wear-resistant parts, such as gear, spline shaft, etc. This type of steel is also called tempered steel.

(3) The carbon content of high carbon steel is greater than 0.6%. This kind of steel has high hardness and strength, but poor plasticity and toughness. If this kind of steel after quenching and tempering, not only has a high strength and good elasticity. It is mainly used to make some springs that do not require too much performance. Such as valve spring, plate spring, gyrospring and spring ring, etc.

2. Score according to quality:

Ordinary carbon steel, high quality carbon steel, high quality carbon steel.

The National Standard for ordinary carbon structural steel (GB700-1988) stipulates that the grade of carbon structural steel consists of the following four parts.

(1) Yield strength letter Q - yield strength.

(2) The numerical unit of yield strength is Mpa.

(3) Quality grade symbols A, B, C, D grade from A to B increase successively.

(4) deoxidation method symbol F - boiling steel; b -- semi-killed steel; Z-town

Static steel; TZ -- special sedative steel Z and TZ are omitted.

Example :Q235AF - represents Grade A boiling steel with yield strength of 235Mpa.