Classification of carbon steel

1. Classification by carbon content

According to the carbon content, carbon steel can be divided into the following three categories:

Low carbon steel (also known as mild steel)

Carbon content: ≤0.25%

Features: good plasticity and toughness, easy to process and weld.

Typical uses: plates, pipes, building materials, etc.

Medium carbon steel

Carbon content: 0.25%~0.6%

Features: high strength and hardness, but slightly poor plasticity and toughness, suitable for heat treatment.

Typical uses: mechanical parts, axles, gears, etc.

High carbon steel (also known as tool steel)

Carbon content: 0.6%~2.0%

Features: high strength and hardness, but low plasticity and toughness, often used in tool manufacturing.

Typical uses: knives, molds, springs, etc.

2. Classification by manganese content

Ordinary carbon steel

Manganese content: 0.25%~0.8%.

It is widely used and is a common basic material.

High-quality carbon steel

The manganese content is relatively high (generally 0.8%~1.2%).

The performance is more uniform and suitable for high-demand mechanical parts.

3. Classification by quality grade

Ordinary carbon structural steel

Standard: GB/T 700 (such as Q235).

Features: low cost, widely used in construction and engineering.

High-quality carbon structural steel

Standard: GB/T 699 (such as 45 steel).

Features: excellent performance, widely used in machinery manufacturing.

Carbon tool steel

Standard: GB/T 1298 (such as T8, T10).

Features: strong wear resistance, suitable for manufacturing cutting tools and molds.

4. Classification by use

Structural carbon steel

Mainly used in engineering fields such as construction, bridges, and shipbuilding.

Tool carbon steel

Used to manufacture knives, molds and measuring tools.

Special purpose carbon steel

For example, free-cutting steel, spring steel, bearing steel, etc.

5. Classification by deoxidation method

Boiling steel (F steel)

Features: incomplete deoxidation, more impurities, low cost.

Suitable for occasions with low performance requirements.

Killed steel (Z steel)

Features: Complete deoxidation, better quality than rimmed steel.

Commonly used in fields with high performance requirements.

Semi-killed steel

Features: Performance is between rimmed steel and killed steel, and the cost is moderate.

Semi-killed steel is often used to produce steel for building structures. These structural components require certain strength and toughness, and semi-killed steel can meet these requirements while having certain economy.

Killed steel picture