Application of steel materials

There are many types of steel, but they can be broadly divided into two categories: carbon steel and alloy steel

Steel is the most widely used metal material. They are all iron-carbon alloys. The difference lies in the amount of carbon. In theory, Carbon content below 2.6% is steel, above iron. In fact, the carbon content of steel is generally below 1.4%, and the carbon content of iron is between 2.5~4.0%.

Classification and application of steel

There are many types of steel, but they can be broadly divided into two categories:

carbon steel and alloy steel:

Carbon steel: ordinary carbon steel, high-quality carbon steel, carbon tool steel

Alloy steel: alloy structural steel, alloy tool steel, special performance alloy steel

Carbon steel According to the carbon content, carbon steel is divided into: low carbon steel (<0.25%=, medium carbon steel (0.25~0.6%C), and High carbon steel (0.6~1.4%C). The national grades divide carbon steel into:

a.Ordinary carbon steel:

The average carbon content is 0.1~0.6%, the phosphorus content is ≤0.04%, and the sulfur content is 0.055%. Ordinary carbon structural steel belongs to engineering structural steel. Because of its low price, it is often used to manufacture machines with low requirements. Parts, such as screws, bolts, nuts, washers, handles, small shafts, etc.

b. High-quality carbon structural steel

In the smelting process, proper refining should be carried out, not only the carbon content is accurate, but also the removal of impurities such as phosphorus and sulfur is relatively clean. (≤0.04%P,≤0.04%S). The plasticity of this type of steel is higher than that of ordinary carbon structural steel, and it is not easy to crack during quenching, welding, forging and cold deformation. Applied to more important machine parts. Such as guide bushes, stops, friction plates, gears, screw rods, connecting rods and various shaft parts, Spring, etc.

c. Carbon tool steel

The average carbon content is 0.1~1.3%, which is a high-carbon steel with high hardness and wear resistance. Compared with structural steel, this type of steel has a higher quality and requires a particularly low content of impurities such as phosphorus and sulfur. It is refined High-quality steel. With high hardness and wear resistance, it is mainly used to manufacture knives, measuring tools and abrasive tools, but also to manufacture wear resistance Components.

Alloy steel

On the basis of carbon steel, it contains some Cr. Ni, Mo, W. V. Ti, B and other elements, or contains more The Si and Mn elements become alloy steel. According to the content of alloying elements, the alloy steel is divided into: low alloy steel ( <2.5%) Medium alloy steel (2.3%) and high alloy steel (> 10%). Alloy steel is divided into three categories according to its purpose.

a.Alloy structural steel

Alloy structural steel includes ordinary low-alloy structural steel and machine structural steel. The former is widely used in ships, vehicles, oil pipes, etc. The latter is used to manufacture parts such as piston pins, connecting rod bolts, transmission gears and precision boring bars.

b. Alloy tool steel

After proper heat treatment of this kind of steel, high hardness and wear resistance can be obtained. It is the manufacturing tool, measuring tool and mold. Tool steel. Such as die casting die steel, forging die steel, cold punch die steel and die, tap, reamer, turning tool, twist drill .

c.Special performance alloy steel

It has special physical and chemical properties, such as wear resistance, heat resistance, oxygen resistance, antimagnetic, magnetic permeability, etc. It belongs to special performance alloys Common steels include stainless steel, heat-resistant steel, wear-resistant steel and magnetic steel.