High-Carbon Steel: Uses, Composition, and Its Properties
High-carbon steel is defined by a carbon content of between 0.6% and 1.0%. A lower carbon content will define the metal as either low-carbon or medium-carbon steel, and those with a higher percentage are ultra-high-carbon steels. The hardness, corrosion resistance, and cost all rise in proportion to the carbon content of this form of steel. This is why high-carbon steel is used in knives, swords, masonry nails, and gear wheels. High-carbon steel, like other forms of steel, is produced by melting either recycled steel or pig iron, removing any impurities, and then adding alloying elements to produce the right chemical composition before casting or extruding the molten metal.
This article will discuss high-carbon steel, its uses, composition, and properties.
What Is High-Carbon Steel?
High-carbon steel is steel with a carbon content of 0.6-1.0%. This carbon content changes the structure of the steel by increasing both hardness and brittleness. High-carbon steel is also known as carbon tool steel or M2 steel. The name M2 comes from the M-series of steels that employ molybdenum to increase hardness, strength, and corrosion resistance.
How Is High-Carbon Steel Made?
Molten steel, by nature, dissolves carbon at high temperatures but typically releases it if it cools slowly. To create high-carbon steel, manufacturers must prevent steel from releasing carbon as it cools. To accomplish this, the steel is quenched to increase the cooling rate from roughly 200 °C per minute to 1000 °C per minute. The carbon does not have time to escape the metal’s lattice structure, so internal stresses in the microstructure are retained. Internal stresses sound bad, but in this case, they improve the hardness and strength of the steel.
How Does High-Carbon Steel Differ From Stainless Steel?
The difference between high-carbon steel and stainless steel is that stainless steel has at least 10.5% chromium content while high-carbon steel has less (or none at all). Although they both have a high carbon content, the chromium makes stainless steel more corrosion-resistant. High-carbon steel rusts more easily but has better tensile strength.
How Much Does High-Carbon Steel Cost?
High-carbon steel is more expensive than its mild counterparts because it contains so much alloying carbon. However, it is cheaper than stainless steel which has a high alloying content of chromium and molybdenum. The price of high-carbon steel depends on the form, grade, availability, and supplier, but it generally costs $800-1,000 per ton.
Is High-Carbon Steel a High-Alloy Steel?
No, high-carbon steel and high-alloy steel are two different concepts. While carbon is technically an alloying element and high-carbon steel has a significant amount of it, this is not the same as high-alloy steel. The latter term gets applied to steel with high percentages of other alloying elements such as chromium and molybdenum. An example of a high-alloy steel is stainless steel which contains more than 10.5% chromium.
To learn more, see our guide on Alloy Steel Material Properties.
What Are the Different Types of High-Carbon Steel?
Different types of high-carbon steel are used for different applications. The major ones are discussed below:
1. Alloyed Carbon Steel
Alloyed carbon steels are produced by adding other alloying elements to high-carbon steel. This is done to improve their properties but only when required since it also makes the metal far more expensive. Alloyed carbon steels can include constituents like: chromium, cobalt, manganese, molybdenum, nickel, tungsten, or vanadium. These elements can be used to improve heat resistance, tensile strength, corrosion resistance, hardness, toughness, and more. One common example of an alloyed carbon steel is stainless steel.
2. Spring Steel
Spring steel has a carbon content of 0.6-1%, and it may also have varying amounts of nickel, manganese, chromium, vanadium, and molybdenum. Above all, though, spring steel must contain silicon to earn the name. Silicon makes the steel flexible and gives it a high yield strength.
3. Plain Carbon Steel
Plain carbon steel has no other alloying elements of significance and therefore is the cheapest form of high-carbon steel. Plain carbon steel is hard to weld, fails after minimal elongation, and is sensitive to heat treatments,
4. Tool Steel
Tool steel gets alloyed with tungsten, molybdenum, cobalt, and vanadium to enhance its durability and heat resistance. The heat resistance of tool steel prevents the metal from tempering when heated since that would diminish the tool's strength. To learn more, see our guide on Tool Steel Composition.
What Are the Uses of High-Carbon Steel?
The increased hardness and relatively low price point of high-carbon steel lend themselves to many applications such as those listed below:
- Cutting tools
- Springs
- Knives
- Fasteners
- Masonry nails
- Gear wheels
- Chains
- Pneumatic drill bits
- Shears
Is High-Carbon Steel Good for Knives?
Yes, high-carbon steel is a perfect option for knives. The significant carbon content of this steel makes it tough, durable, and easy to sharpen. The downside is that it’s prone to corrosion. High-carbon steel is often fashioned into machetes and survival knives. Stainless steel is a high-carbon steel competitor when it comes to knives because it resists corrosion, but at the same time, it’s less tough and more expensive.
What Is the Chemical Composition of High-Carbon Steel?
High-carbon steel has a very simple chemical composition. It typically consists of 0.60-1.00% carbon and 0.30-0.90% manganese, with the remaining content being iron (98.1-99.1%). Table 1 lists the chemical composition of high-carbon steel in detail:
| Element | Content |
|---|---|
Element Iron | Content 98.10 - 99.10% |
Element Carbon | Content 00.60 - 01.00% |
Element Manganese | Content 00.30 - 00.90% |
What Is the Carbon Content of High-Carbon Steel?
The carbon content of high-carbon steel is 0.6-1.0% carbon. Any more than this would make it an ultra-high-carbon steel and any less is a medium-carbon steel. These small differences in carbon content have big impacts on the steel's properties. According to the iron-carbon phase diagram, high-carbon steel austenite, when cooled, will undergo a eutectoid transformation into two phases. It becomes either pearlite + ferrite or pearlite + cementite. Upon cooling, a large amount of the carbon will become trapped in the lattice structure of the steel, pushing apart the iron atoms in the structure and creating internal stresses that make it harder and more brittle.
What Are the Properties of High-Carbon Steel?
Table 2 lists some properties of high-carbon steel:
| Property | AISI 1060 Values | AISI 52100 Values |
|---|---|---|
Property Density | AISI 1060 Values 7.85 g/cm² | AISI 52100 Values 7.81 g/cm² |
Property Yield Strength | AISI 1060 Values 485 MPa | AISI 52100 Values 2033 MPa |
Property Hardness (Rockwell B) | AISI 1060 Values 89 | AISI 52100 Values 64 |
Property Magnetism (Curie point) | AISI 1060 Values 770 ºC | AISI 52100 Values 770 ºC |
What Is the Machinability Rating of High-Carbon Steel?
A high-carbon steel grade such as 1060 steel, which has 0.6% carbon, will have a machinability rating of 57% while 1095 steel, which has 0.95% carbon, has a machinability rating of 45%. The carbon content of steel directly impacts its machinability rating. Steels with 0.2% carbon have the best machinability rating. Steels with less than 0.2% will tear rather than cut while those which contain more than 0.2% get increasingly hard. All high-carbon steels lie well above this 0.2% threshold.
What Are the Characteristics of High-Carbon Steel?
High-carbon steel has many characteristics that make it a desirable material for things such as household appliances, toys, manufacturing tools, automotive parts, and construction products. These characteristics include:
- High strength
- Resistance to wear
- Hardness
- Brittleness
Is High-Carbon Steel the Strongest?
In most contexts, yes, high-carbon steel is the strongest type of carbon steel you’ll usually encounter. It’s notably stronger than stainless, medium-carbon, and low-carbon steel. The greater number of carbon atoms in the lattice structure increases its hardness, strength, and wear resistance. However, certain alloy steels that contain chromium and/or manganese can surpass the strength of high-carbon steel.
Is High-Carbon Steel Rust-Resistant?
No. High-carbon steel does not resist rust to a significant degree, though it does fare better than its low-carbon counterparts. Rust can be prevented in high-carbon steel by proper treatment and maintenance. For example, protective oil or paint coatings or regular cleaning with water or a mild detergent can all help protect the surface from rust and make it more durable.
Can High-Carbon Steel Be Welded?
Yes, high-carbon steel can be welded. However, it is more prone to weld-related cracking than medium-carbon or low-carbon steel. To avoid such cracking, the steel part should undergo a thorough heating process both before and after welding.
Is High-Carbon Steel Corrosion-Resistant?
The answer to this question depends on your perspective. High-carbon steel resists corrosion better than its low- and medium-carbon counterparts. That’s a reason why it is so often employed in pressure tanks and bridges. However, high-carbon steel has nowhere near the degree of corrosion resistance seen in stainless steel. The latter owes its corrosion-resistant properties primarily to its inclusion of at least 10.5% chromium. Although resistance to corrosion does scale with the carbon content, it can’t compare to a high chromium content. It is also important to note that high-carbon steel is particularly vulnerable to corrosion from sulfuric acid or salt water.
Is High-Carbon Steel Brittle?
Yes. High-carbon steel is considered to be brittle in comparison to many other engineering metals. This is due to the large amounts of carbon present. Carbon strengthens the structure and affords it the ability to harden when exposed to heat, but also makes it less weldable and ductile than ordinary steel. All the impurities in high-carbon steel can make it more brittle and prone to fracturing.
What Are the Thermal Properties of High-Carbon Steel?
The thermal properties of high-carbon steel are listed in Table 3 below:
| Thermal Property | Value |
|---|---|
Thermal Property Melting point | Value 1540 - 1590℃ |
Thermal Property Thermal conductivity | Value 19.0 - 52.0 W/m⦁K |
Thermal Property Coefficient of Thermal Expansion | Value 9.9 - 14.8 µm/m⦁ºC |
Thermal Property Specific Heat Capacity | Value 0.410 - 0669 J/g⦁ºC |
What Are the Common Forms of High-Carbon Steel Material?
High-carbon steel is available in some forms. Each form has a very similar chemical composition but may vary in its characteristics, microstructure, and applications. These different forms of high-carbon steel include:
Hot-Rolled Steel
The hot-rolling process is carried out near the recrystallization temperature. Hot-rolling leaves fewer residual internal stresses in its structure. This makes for steel that is less hard than its cold-rolled counterpart. Hot-rolled steel is not as strong as the cold-rolled version because the hot-rolling process allows for recrystallization, which, in turn, creates finer grains in the steel microstructure. These finer crystals are more prone to dislocation.
The upshot is that hot-rolled steel is cheaper since the production process demands less energy than cold rolling. However, hot-rolled high-carbon steel is less dimensionally accurate because the material shrinks as it cools, making dimensions more challenging to control. Hot-rolled high-carbon steel is used in construction and railroad tracks where tolerances aren’t overly strict.
Cold-Rolled Steel
Cold rolling is carried out at room temperature. Cold-rolled high-carbon steel is harder, has a better surface finish, and is more dimensionally accurate than hot-rolled steel, though it’s less ductile. During cold rolling, the grains of the metal are elongated which strain-hardens the material. This steel must be stressed and relieved before being used because it may otherwise begin to warp. Its uses include: electric motors, water heaters, frying pans, and pressure vessels.
Tempered Steel
Tempering increases the strength and hardness of high-carbon steels. By reheating the high-carbon steel to just below its eutectoid point, allowing the carbon to be dissolved in the lattice structure, and then quenching it, the carbon is trapped in the structure. This altered crystal lattice is called martensite, and it’s harder and stronger than other steel microstructures. Tempered steel is used in swords, knives, tools, and construction equipment.
What Are the Equivalents of High-Carbon Steel?
There are many grades of high-carbon steel. They’re largely differentiated by their carbon content. An example of high-carbon steel is 1060, some equivalents of which are listed in Table 4 below:
| Country | Equivalent Grade |
|---|---|
Country EN | Equivalent Grade C60 |
Country Germany | Equivalent Grade C60 |
Country England | Equivalent Grade 070M60 |
Country Italy | Equivalent Grade 1C60 |
Country Japan | Equivalent Grade S58C |
Country China | Equivalent Grade 60 |
Country Russia | Equivalent Grade 60 |
What Are the Advantages of Using High-Carbon Steel?
High-carbon steel has many advantages compared to other steels and is particularly effective for construction materials, automotive components, and tools. Examples of the advantages are:
- High strength
- High hardness
- Low cost
- Unlikely to stress and break under pressure
- Resistance to wear
What Are the Disadvantages of Using High-Carbon Steel?
Whilst high-carbon steel has lots of benefits, the large quantities of carbon within it create some disadvantages as well:
- Susceptible to corrosion
- Poor weldability
- Low ductility and malleability
- Difficult to cut and form
What Is an Example of High-Carbon Steel?
Carbon steel is graded using the prefix 10XX. The “XX” is a placeholder for the number which represents the carbon content of the steel. For example, 1060 steel has 0.6% carbon and 1095 has 0.95% carbon. 1060 is a general-purpose steel that is valued for its hardness in items such as: axles, gears, clutch discs, and train wheels.
Is High-Carbon Steel Better Than Stainless Steel?
Yes, high-carbon steel is better than stainless steel for applications that require hardness. However, stainless steel is the better choice in corrosive environments. High-carbon steel is better for some knives, cutting tools, and gears, and stainless steel is better for applications like: medical instruments, food processing equipment, and boat components.
To learn more, see our guide on What is Stainless Steel.
What Is the Difference Between High-Carbon Steel and Medium-Carbon Steel?
The main difference between high-carbon steel and medium-carbon steel is the ratio of carbon to iron. In high-carbon steel, the carbon content is 0.6-1.0% carbon, whereas medium-carbon levels run between 0.3% and 0.6%. This difference means that high-carbon steel is stronger and harder than medium-carbon steel, but medium-carbon steel is more ductile.
Summary
This article presented high-carbon steel, explained it, and discussed its various uses and properties. To learn more about high-carbon steel, contact a Xometry representative.
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