24 Types of Steel You Should Know

Do you know how many types of steel there are?

What are the characteristics of each steel?

Today I will explain 24 kinds of steel.

I believe there must be something you don’t know.

Let’s dive into it.

1. Carbon steel

Carbon steel, also known as carbon steel, is a ferrocarbon alloy with a carbon content (wc) of less than 2%.

Carbon steel generally contains a small amount of silicon, manganese, sulfur and phosphorus in addition to carbon.

Carbon steel can be divided into carbon structural steel, carbon tool steel and free cutting structural steel.

Carbon structural steel can be divided into building structural steel and machine manufacturing structural steel.

Carbon steel can be divided into low carbon steel (wc ≤ 0.25%), medium carbon steel (wc 0.25%~0.6%) and high carbon steel (wc>0.6%) according to carbon content.

According to phosphorus and sulfur content, carbon steel can be divided into ordinary carbon steel (with higher phosphorus and sulfur content), high-quality carbon steel (with lower phosphorus and sulfur content) and high-grade high-quality steel (with lower phosphorus and sulfur content).

Generally, the higher the carbon content in carbon steel is, the higher the hardness and strength are, but the plasticity is reduced.

2. Carbon structural steel

This type of steel mainly guarantees the mechanical properties, so its brand reflects its mechanical properties, expressed by Q+numbers, where “Q” refers to the yield point, and the number represents the yield point value, for example, Q275 represents the yield point of 275MPa.

If the letters A, B, C and D are marked behind the grade, it means that the steel quality grade is different, the content of S and P decreases in turn, and the steel quality increases in turn.

If the letter “F” is marked behind the grade, it is rimmed steel; if “b” is marked, it is semi killed steel; if “F” or “b” is not marked, it is killed steel.

For example, Q235-A · F represents Grade A rimmed steel with a yield point of 235MPa, and Q235-c represents Grade C killed steel with a yield point of 235MPa.

Carbon structural steel is generally used in the supply state without heat treatment.

Generally, Q195, Q215 and Q235 steels have low carbon content, good welding performance, good plasticity and toughness, and certain strength.

They are often rolled into thin plates, reinforcing bars, welded steel pipes, etc., and used for bridges, buildings and other structures, and for manufacturing ordinary rivets, screws, nuts and other parts.

Q255 and Q275 steels have slightly higher carbon content, higher strength, better plasticity and toughness, and can be welded.

Generally, rolled formed steel, strip steel and steel plate are used as structural members, as well as connecting rods, gears, couplings, pins and other parts for manufacturing simple machines.

3. High-quality structural steel

This kind of steel must ensure both chemical composition and mechanical properties.

The grade is expressed by two digits, i.e., 10000% of the average carbon mass fraction in the steel (wс× 10000).

For example, 45 steel means that the average carbon mass fraction in the steel is 0.45%;

08 steel means that the average carbon mass fraction in steel is 0.08%.

High quality carbon structural steel is mainly used to manufacture machine parts.

Generally, heat treatment is required to improve mechanical properties.

There are different uses according to the carbon mass fraction.

08, 08F, 10, 10F steel, with high plasticity and toughness, has excellent cold forming performance and welding performance, and is often cold-rolled into thin plates, which are used to make cold stamping parts on instrument housings, automobiles and tractors, such as automobile bodies, tractor cabs, etc;

15, 20, 25 steel is used to make carburized parts with small size, light load, wear-resistant surface requirements and low central strength requirements, such as piston pin and sample plate;

After heat treatment (quenching+high temperature tempering), steel 30, 35, 40, 45 and 50 have good comprehensive mechanical properties, that is, they have high strength, high plasticity and toughness, and are used to make axle parts.

For example, steel 40 and 45 are often used to make crankshafts, connecting rods, spindles of general machine tools, gear of machine tools and other axle parts with low stress;

55, 60 and 65 steels have high elastic limit after heat treatment (quenching+medium temperature tempering).

They are commonly used to make springs with small load and small size (section size less than 12~15mm), such as pressure regulating and speed regulating springs, plunger springs, cold coiled springs, etc.

4. Carbon tool steel

Carbon tool steel is a kind of high carbon steel that basically does not contain alloy elements.

Its carbon content ranges from 0.65% to 1.35%.

It has low production cost, easy access to raw materials, good machinability, and high hardness and wear resistance after treatment.

Therefore, it is widely used to manufacture various cutting tools, molds, and measuring tools.

Related reading: Cutting Tools Basics

However, this kind of steel has poor red hardness, that is, when the working temperature is greater than 250 ℃, the hardness and wear resistance of the steel will drop sharply and lose the working ability.

In addition, carbon tool steel is not easy to harden if it is made into larger parts, and it is easy to produce deformation and cracks.

5. Free-cutting structural steel

Free cutting structural steel is to add some elements that make the steel brittle, so that the chips are easy to break into chips during steel cutting, which is conducive to improving the cutting speed and prolonging the tool life.

Sulfur is the main element that makes steel brittle.

Lead, tellurium, bismuth and other elements are used in ordinary low alloy-free cutting structural steel.

The sulfur content ws of this steel is 0.08% – 0.30%, and the manganese content wMn is 0.60% – 1.55%.

The sulfur and manganese in steel exist in the form of manganese sulfide, which is very brittle and has lubrication efficiency, so that the chip is easy to break, and is conducive to improving the quality of the machined surface.

6. Alloy steel

In addition to iron, carbon and a small amount of inevitable silicon, manganese, phosphorus and sulfur elements, steel also contains a certain amount of alloy elements.

The alloy elements in steel include one or more of silicon, manganese, molybdenum, nickel, chromium, vanadium, titanium, niobium, boron, lead and rare earth.

This steel is called alloy steel.

The alloy steel systems of various countries vary with their respective resources, production and use conditions.

Nickel and chromium steel systems have been developed abroad in the past, while China has developed alloy steel systems based on silicon, manganese, vanadium, titanium, niobium, boron and rare earth.

Alloy steel accounts for about 10% of the total output of steel.

Generally, alloy steel smelted in electric furnace can be divided into 8 categories according to the use, including alloy structural steel, spring steel, bearing steel, alloy tool steel, high-speed tool steel, stainless steel, heat resistant and non peeling steel, and silicon steel for electrical engineering.

7. Ordinary low alloy steel

Ordinary low alloy steel is a kind of ordinary alloy steel containing a small amount of alloy elements (in most cases, the total amount of w does not exceed 3%).

This kind of steel has high strength, good comprehensive properties, corrosion resistance, wear resistance, low temperature resistance, and good cutting and welding properties.

Under the condition of saving a lot of rare alloy elements (such as nickel and chromium), 1t ordinary low alloy steel can be used for 1.2-1.3t carbon steel, and its service life and scope of use are far more than carbon steel.

Ordinary low alloy steel can be smelted in open hearth furnace and converter with general smelting method, and the cost is close to that of carbon steel.

8. Engineering structural steel

This refers to alloy steels used for engineering and building structures, including weldable high-strength alloy structural steels, alloy reinforcement steels, alloy steels for railways, alloy steels for geological oil drilling, alloy steels for pressure vessels, high manganese wear-resistant steels, etc.

This kind of steel is used as engineering and building structural members.

In alloy steel, the total alloy content of this kind of steel is low, but the production and use are large.

9. Mechanical structural steel

This kind of steel refers to alloy steel suitable for manufacturing machines and machine parts.

On the basis of high-quality carbon turbulence steel, one or several alloy elements are properly added to improve the strength, toughness and hardenability of the steel.

This kind of steel is usually used after heat treatment (such as quenching and tempering treatment, surface hardening treatment).

It mainly includes two categories of commonly used alloy structural steel and alloy spring steel, including quenched and tempered alloy steel, surface hardened alloy steel (carburized steel, nitrided steel, surface high-frequency quenched steel, etc.), and alloy steel for cold plastic forming (cold heading steel, cold extrusion steel, etc.).

According to the basic composition series of chemical composition, it can be divided into Mn series steel, SiMn series steel, Cr series steel, CrMo series steel, CrNiMo series steel, Nj series steel, B series steel, etc.

10. Alloy structural steel

The carbon content wc of alloy structural steel is lower than that of carbon structural steel, generally in the range of 0.15% – 0.50%.

In addition to carbon, it also contains one or several alloy elements, such as silicon, manganese, vanadium, titanium, boron, nickel, chromium, molybdenum, etc.

Alloy structural steel is easy to harden and not easy to deform or crack, which is convenient for heat treatment to improve the performance of steel.

Alloy structural steel is widely used to manufacture various transmission parts and fasteners for automobiles, tractors, ships, steam turbines and heavy machine tools.

Low carbon alloy steel is generally carburized, and medium carbon alloy steel is generally quenched and tempered.

11. Alloy tool steel

Alloy tool steels are medium and high carbon steels containing a variety of alloy elements, such as silicon, chromium, tungsten, molybdenum, vanadium, etc.

Alloy tool steel is easy to harden, and is not easy to produce deformation and cracks.

It is suitable for manufacturing large and complex cutting tools, dies and measuring tools.

The carbon content of alloy tool steel varies with different applications.

The carbon content of most alloy tool steels is 0.5%~1.5%.

The carbon content of hot deformation die steel is low, and the wc is in the range of 0.3%~0.6%;

Steel for cutting tools generally contains about 1% carbon wc;

The carbon content of steel for cold working dies is relatively high, for example, the carbon content of graphite die steel is 1.5%, and the carbon content of steel for high carbon and high chromium cold working dies is more than 2%.

12. High-speed tool steel

High speed tool steel is a high carbon and high alloy tool steel.

The carbon content in the steel is 0.7% – 1.4%.

The steel contains alloy elements that can form high-hardness carbides, such as tungsten, molybdenum, chromium and vanadium.

High speed tool steel has high red hardness.

Under the condition of high speed cutting, the hardness will not decrease even when the temperature reaches 500-600 ℃, thus ensuring good cutting performance.

13. Spring steel

Spring is used under impact, vibration or long-term alternating stress, so spring steel is required to have high tensile strength, elastic limit and high fatigue strength.

In terms of technology, it is required that the spring steel has certain hardenability, is not easy to decarburize, and has good surface quality.

Carbon spring steel refers to high-quality carbon structural steel with a carbon content of 0.6%~0.9% (including normal and high manganese content).

Alloy spring steel is mainly silicon manganese steel, and their carbon content is slightly lower, mainly by increasing the silicon content WSi (1.3% ~ 2.8%) to improve the properties;

In addition, there are chromium, tungsten and vanadium alloy spring steels.

Combined with the resources of our country and according to the requirements of new technologies for automobile and tractor design, a new steel grade with boron, niobium, molybdenum and other elements added on the basis of silicon manganese steel has been developed, which extends the service life of the spring and improves the quality of the spring.

14. Bearing steel

Bearing steel is used to make balls, rollers and bearing rings.

Bearing bears great pressure and friction when working, so bearing steel is required to have high and uniform hardness, wear resistance and high elastic limit.

The requirements for the uniformity of chemical composition, the content and distribution of non-metallic inclusions, and the distribution of carbides of bearing steel are very strict.

Bearing steel is also called high carbon chromium steel.

The carbon content wc is about 1%, and the chromium content wc is 0.5% – 1.65%.

Bearing steel is divided into high carbon chromium bearing steel, chromium free bearing steel, carburized bearing steel, stainless bearing steel, medium and high temperature bearing steel and antimagnetic bearing steel.

15. Electrical silicon steel

Silicon steel for electrical industry is mainly used to make silicon steel sheets for electrical industry.

Silicon steel sheet is a large amount of steel used in motor and transformer manufacturing.

Silicon steel can be divided into low silicon steel and high silicon steel according to chemical composition.

The silicon content of low silicon steel is 1.0% ~ 2.5%, which is mainly used to manufacture motors;

The silicon content of high silicon steel is 3.0% ~ 4.5%, which is generally used to manufacture transformers.

Their carbon content wc ≤ 0.06%~0.08%.

16. Rail steel

The steel rail mainly bears the pressure and impact load of rolling stock, so it is required to have sufficient strength, hardness and certain toughness.

The rail steel commonly used is carbon-killed steel smelted in an open hearth furnace and converter.

This steel contains 0.6%~0.8% carbon, belonging to medium carbon steel and high carbon steel.

However, the manganese content in steel is high, within the range of 0.6%~1.1%.

Ordinary low alloy steel rails have been widely used, such as high silicon rail, medium manganese rail, copper rail, titanium rail, etc.

The common low alloy rail is more wear-resistant and corrosion resistant than the carbon rail, and its service life is greatly improved.

17. Shipbuilding steel

Shipbuilding steel refers to the steel used to manufacture seagoing ships and large inland river hull structures.

As the hull structure is generally made by welding, shipbuilding steel is required to have good welding performance.

In addition, certain strength, toughness and low temperature and corrosion resistance are also required.

In the past, low carbon steel was mainly used as shipbuilding steel.

Ordinary low alloy steel has been widely used, and the existing steel grades include 12 manganese ship, 16 manganese ship, 15 manganese vanadium ship, etc.

These steel grades have high strength, good toughness, easy processing and welding, seawater corrosion resistance and other comprehensive characteristics, and can be successfully used to manufacture 10000 ton ocean going giant ships.

18. Bridge steel

Railway or highway bridges bear the impact load of vehicles.

Bridge steel is required to have certain strength, toughness and good fatigue resistance, and has high requirements on the surface quality of steel.

Basic open hearth killed steel is often used as bridge steel, and common low alloy steel such as 16 manganese, 15 manganese vanadium nitrogen is successfully used.

19. Boiler steel

Boiler steel mainly refers to the materials used to manufacture superheater, main steam pipe and heating surface of boiler fire chamber.

The performance requirements of boiler steel are mainly good welding performance, certain high temperature strength, alkali corrosion resistance, oxidation resistance, etc.

The commonly used boiler steels are low carbon killed steel smelted in open hearth furnace or low carbon steel smelted in electric furnace, and the carbon content wc ranges from 0.16% to 0.26%.

Pearlitic heat-resistant steel or austenitic heat-resistant steel shall be used when manufacturing high-pressure boilers.

Ordinary low alloy steel is also used to build boilers, such as 12 manganese, 15 manganese vanadium, 18 manganese molybdenum niobium, etc.

20. Steel for welding rod

This kind of steel is specially used for making wire for electric arc welding and gas welding electrodes.

The composition of steel varies with the material being welded.

As required, it can be roughly divided into three categories: carbon steel, alloy structural steel and stainless steel.

The sulfur and phosphorus content ws and wP of these steels are not more than 0.03%, which is stricter than that of ordinary steels.

These steels do not require mechanical properties, but are only tested for chemical composition.

21. Stainless steel

Stainless and acid resistant steel is called stainless steel for short, which is composed of stainless steel and acid resistant steel.

In short, the steel that can resist atmospheric corrosion is called stainless steel, and the steel that can resist chemical medium (such as acid) corrosion is called acid resistant steel.

Generally speaking, the steel with chromium content greater than 12% has the characteristics of stainless steel.

According to the microstructure after heat treatment, stainless steel can be divided into five categories: ferritic stainless steel, martensitic stainless steel, austenitic stainless steel, austenitic ferritic stainless steel and precipitation hardening stainless steel.

22. Heat resistant steel

Under high temperature conditions, the steel with oxidation resistance, sufficient high temperature strength and good heat resistance is called heat resistant steel.

Heat resistant steel includes oxidation resistant steel and heat strength steel.

The oxidation resistant steel is also called non peeling steel.

Heat strength steel refers to the steel with good oxidation resistance and high high temperature strength at high temperature.

Heat resistant steel is mainly used for parts used for a long time under high temperature.

23. Superalloy

Superalloy is a kind of thermal strength material with sufficient endurance strength, creep strength, thermal fatigue strength, high temperature toughness and sufficient chemical stability at high temperature.

It is used for thermal power components working at high temperature above 600 ℃.

According to their basic chemical composition, they can be divided into nickel base superalloys, iron nickel base superalloys and cobalt base superalloys.

24. Precision alloy

Precision alloy refers to the alloy with special physical properties.

It is an indispensable material in electrical industry, electronic industry, precision instrument industry and automatic control system.

According to their different physical properties, precision alloys can be divided into seven categories: soft magnetic alloys, deformed permanent magnetic alloys, elastic alloys, expansion alloys, thermal bimetals, resistance alloys, and thermocouple alloys.

The vast majority of precision alloys are based on ferrous metals, and only a few are based on nonferrous metals.

Note: Wc, Ws, Wmn and Wp represent the mass fraction of C, S, Mn and P respectively.

FAQs about types of steel

How to classify steels?

What is steel?

Here is the definition:

Steel is an iron-carbon alloy with a carbon content of 0.04%-2.3%.

In order to ensure its toughness and plasticity, the carbon content of steel is generally not more than 1.7%.

The main elements of steel are iron and carbon, as well as silicon, manganese, sulfur and phosphorus.

The classification methods of steel are varied, and the main methods are as follows:

Steel Classification

Classification by quality. 

  • Ordinary steel(P≤0.045%,S≤0.050%) 
  • High-quality steel(P、S≤0.035%) 
  • Advanced high-quality steel(P≤0.035%,S≤0.030%) 

Classification by chemical composition.

(1) Carbon steel

  • Low carbon steel(C≤0.25%)
  • Medium carbon steel(C≤0.25~0.60%)
  • High carbon steel(C≤0.60%)

(2) Alloy steel

  • Low alloy steel(Total amount of alloying element≤5%)
  • Medium alloy steel(Total amount of alloying element>5~10%)
  • High alloy steel(Total amount of alloying element.>10%)

Classification by forming method.

  • Forged steel
  • Cast steel
  • Hot rolled steel
  • Cold drawn steel

Classification by metallographic structure.

(1) Annealed

  • Hyposteel(ferrite +pearlite)
  • Eutectoid steel(pearlite)
  • Hypereutectoid steel(pearlite +cementite)
  • Ledeburitic steel(pearlite +cementite)

(2) Normalized

  • Pearlitic steel
  • Bainite steel
  • Martensitic steel
  • Austenitic steel 

(3) Without phase change or partial phase change.

Classification by use.

(1) Construction and engineering steel

  • Ordinary carbon structural steel
  • Low alloy structural steel.
  • Reinforced steel

(2) Structural steel

a. Mechanical manufacturing steel

  • Tempered structural steel
  • Surface hardening structural steel: including carburized steel, carburized steel, surface hardening steel
  • Free-cutting structural steel
  • Cold plastic forming steel: Including cold stamping steel, cold heading steel.

b. Spring steel

c. Bearing steel

(3) Tool steel

  • Carbon tool steel.
  • Alloy tool steel
  • High-speed tool steel

(4) Special performance steel

  • Stainless acid-resisting steel
  • Heat resistant steel: including anti-oxidation steel, refractory steel, air valve steel;
  • Electrothermal alloy steel.
  • Wear-resistant steel
  • Cryogenic steel
  • Electrical steel

(5) Steel for dedicated use

Such as steel for bridge, ship, boiler, pressure vessel, agricultural machinery, etc.

Comprehensive classification

(1) Ordinary steel

a. Carbon structural steel.

  • Q195
  • Q215 (A, B)
  • Q235 (A, B, C)
  • Q255 (A, B)
  • Q275

b. Low alloy structural steel. 

c. General structural steel for a specific purpose.

(2) Quality steel (including high-grade steel)

a. Structural steel

  • Quality carbon structural steel
  • Alloy structural steel
  • Spring steel
  • Free-cutting steel
  • Bearing steel
  • High-quality structural steel for a specific purpose.

b. Tool steel

  • Carbon tool steel.
  • Alloy tool steel
  • High-speed tool steel

c. Special performance steel

  • Stainless acid-resisting steel.
  • Heat resistant steel
  • Electrothermal alloy steel.
  • Electrical steel
  • High manganese steel

Classification by smelting method.

(1) Classification by the furnace types

a. Open-hearth steel

  • Acid open-hearth steel
  • Basic open-hearth steel

b. Converter steel

  • Acid bessemer steel
  • Basic bessemer steel

OR

  • Bottom blown converter steel
  • Side-blown converter steel
  • Top blown converter steel

c. Arc-furnace steel

  • Electric-art furnace steel
  • Electroslag furnace steel
  • Induction furnace steel
  • Vacuum self-consuming furnace steel
  • Electron beam furnace steel

(2) Classification by the degree of deoxidation and the teeming system.

  • Rimming steel
  • Semi killed steel
  • Killed steel
  • Special killed steel

Related reading: Type of metal

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