7 Classification Methods of Steel You Should Know

Types of metals

First, let’s see the definition of steel.

Definition of metals from Wikipedia:

Steel is an alloy made up of iron with typically a few tenths of a percent of carbon to improve its strength and fracture resistance compared to other forms of iron.

Then how many types of steel are there?

Let’s dive right in.

ferrous metals and non ferrous metals

According to the various cross-sectional shapes, steel is generally classified into four categories: profiles, plates, pipes, and metal products. It is further divided into heavy rail, light rail, large section steel, medium section steel, small section steel, cold-formed steel sections, high-quality steel sections, wire rods, medium-thick steel plates, thin steel plates, silicon steel sheets for electrical purposes, strip steel, seamless steel pipes, welded steel pipes, and various other metal products.

Classified by the smelting process

Steel can be divided into:

  • Hand furnace steel
  • Electric furnace steel
  • Converter steel
Converter smelting

And electric furnace steel can be divided into:

  • Electric arc furnace
  • Induction furnace
  • Vacuum induction furnace
  • Electroslag furnace
Crucible type high frequency induction furnace

Crucible type high frequency induction furnace

Electroslag furnace

Electroslag furnace

Classified by the degree of deoxidation

  • Rimmed Steel (Q235AF)
  • Killed steel (Z)
  • Semi-killed steel (b)
  • Special killed steel (TZ)
Rimmed Steel

Rimmed Steel

Classified by application

Steel can be divided into:

  • Structural steel
  • Tool steel
  • Special performance steel
Tool steel

Tool steel

Specifically, structural steel can be further divided into:

  • Building structural steel
  • Machine manufacturing steel

Tool steel can be divided into:

  • Measuring tool steel
  • Cold mold tool steel
  • Hot mold tool steel
Hot mold tool steel

Hot mold tool steel

Special property steel can be divided into:

  • Impact resistant low-temperature steel
  • Stainless acid resistant steel
  • Weathering resistant steel
  • Electrical steel
Electrical steel

Electrical steel

Classified by the metallographic structure

(1) Based on the equilibrium state and annealed structure, steel is classified into: hypereutectoid steel, eutectoid steel, hypoeutectoid steel, and peritectic steel.

(2) Based on the normalizing structure, steel is classified into: pearlitic steel, bainitic steel, martensitic steel, and austenitic steel.

(3) Based on the metallographic structure during the heating phase with or without phase change, steel is classified into: ferritic steel, austenitic steel, martensitic steel, and duplex steel.

Classified by the chemical component

Carbon steel is divided into:

  • Ordinary carbon steel
  • High-quality carbon steel
  • Advanced carbon steel
Ordinary carbon steel

Ordinary carbon steel

Alloy steel is divided into:

  • Low-alloy steel
  • Medium alloy steel
  • High alloy steel
Alloy steel

Alloy steel

Carbon steel:

Also referred to as mild steel, this material primarily consists of iron, carbon, and a small amount of impurities such as silicon (Si), manganese (Mn), sulfur (S), and phosphorus (P). The impurities present in mild steel do not exceed 2% of the total composition. Based on the carbon content, mild steel can be further categorized into three types:

  • Low carbon steel, which contains less than 0.25% carbon.
  • Medium carbon steel, with a carbon content ranging from 0.25% to 0.6%.
  • High carbon steel, which has a carbon content greater than 0.6%.

Alloy steel:

In addition to the elements found in carbon steel, there are other alloying elements such as chromium (Cr), nickel (Ni), molybdenum (Mo), tungsten (W), vanadium (V), and boron (B). Based on the amount of alloying elements, steel can be further classified into three categories:

  • Low alloy steel, which contains less than 5% of alloying elements.
  • Medium alloy steel, with an alloy content ranging from 5% to 10%.
  • High alloy steel, which has an alloy content greater than 10%.

Alloy Steel

Classified by quality

(1) Ordinary steel

(2) High-quality steel

(3) Premium quality steel A

(4) Special high-quality steel E

Classified by shape

Thick Plate


  • 2-4.0 mm: steel sheet
  • 4-20mm:medium plate
  • >20mm: thick plate


  • Seamless tube (hot rolled, cold drawn and pressed)
  • Seamedwelding tube (straight seam pipe, spiral tube)
Seamless tube

Seamless tube


Angle steel, channel steel, I-beam, round steel, square steel, flat steel and hexagonal steel.


Wire rod:

Rebar, steel wire and iron wire

Wire rod

Now that you are familiar with the various types of steel, you may be interested in learning about the different types of metals. To expand your knowledge on this topic, you can refer to the following post, which provides information on the different types of metals.

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