Alloy Steel vs. Carbon Steel
Learn more about the differences between these two types of steels.
Alloy steel and carbon steel both have very useful properties. Carbon steel is an alloy of iron and carbon, typically containing up to 2% carbon by weight. It is often utilized in the production of: machines, tools, steel buildings, bridges, and other infrastructure. Alloy steel, on the other hand, is a type that contains one or more alloying elements (usually other metals such as: manganese, chromium, and nickel) in addition to carbon. Alloy steel is often used in high-strength parts such as gears, shafts, and axles.
When choosing the right steel for a project, it is important to consider what properties the final product will need to have. For example, if strength and hardness are key requirements, alloy steel may be the better choice. If weldability is a key concern, carbon steel may be the better option. This article will take a detailed look at some of the key differences between alloy steel and carbon steel.
Alloy steel is a type of steel that contains alloying elements (e.g. aluminum, chromium, copper, manganese, nickel, silicon, and titanium) in addition to the carbon found in ordinary carbon steel. These alloying elements enhance the steel’s mechanical properties. Some alloys improve: strength, hardness, wear resistance, and/or corrosion obstruction. Alloy steel is widely used in a variety of applications, especially in the construction, automotive, and aerospace industries.
Carbon steel is a type of steel that contains carbon as the main alloying element. It typically has a higher carbon content than alloy steel. Carbon steel can be used for a variety of applications including automotive parts, construction materials, and hand tools. It is known for its strength and durability and can be heat-treated to increase hardness. Carbon steel is also more susceptible to rust than other types of steel. Carbon steel parts may be manufactured by forging, casting, and machining.
Alloy steel can contain a wide variety of elements that enhance its properties. Table 1 highlights some physical and chemical properties of alloy steel:
Alloy steels have alloying elements (such as chromium, manganese, molybdenum, and nickel) between 1-50%
Good thermal conductivity
High resistance to wear and tear
High resistance to corrosion
A hard and strong material
Carbon steel is an iron-carbon alloy with a carbon content of less than 2.11% by weight.
Resistance to wear and tear
Ductile and can easily be formed into different shapes
Carbon steel is magnetic and can be used in electrical applications
It has a low melting point and can be easily welded
There are many different types of alloy steel, each with unique properties and applications. Several broad categories are listed below:
- Low-alloy steel: These steels are the most common and incorporate carbon, manganese, silicon, copper, nickel, and/or molybdenum. Low-alloy steels are typically weaker and more ductile than others. They are widely used in the construction industry in the form of pipes and beams.
- High-alloy steel: High-alloy steel contains more than 5% of another element such as chromium, vanadium, or tungsten. These steels are incredibly strong and hard, making them ideal for use in automotive construction, power generation, and chemical processing equipment.
- Tool steel: Tool steel is a type of alloy steel that is particularly well-suited for making tools. It contains a high proportion of carbon as well as other elements such as chromium, manganese, and/or tungsten. Tool steels are incredibly hard and durable, making them ideal for use in cutting and drilling tools.
Different types of carbon steel are classified based on the amount of carbon present in the alloy. Below are the categories of carbon steel:
- Low-carbon steel (or mild steel): (also known as mild steel) Contains up to 0.30% carbon.
- Medium-carbon steel: Contains between 0.31% and 0.60% carbon.
- High-carbon steel: Contains between 0.61% and 1.50% carbon.
- Ultra-high-carbon steel: Contains between 1.51% and 2% carbon.
Listed below are the advantages of alloy steel compared to carbon steel:
- Alloy steels are more resistant to wear and tear than carbon steel
- Alloy steels are more resistant to corrosion and can be used in high-temperature environments without fear of damage.
- Alloy steels can be heat-treated to increase their strength and hardness, making them even more durable.
- Alloy steels are generally stronger and tougher than carbon steels.
Listed below are the disadvantages of alloy steel compared to carbon steel:
- Alloy steels are more expensive to produce than carbon steels.
- Alloy steels are more difficult to weld than carbon steels.
- Alloy steels are more susceptible to corrosion than carbon steels.
- Alloy steels have lower hardness and strength compared to carbon steels.
- Carbon steels can be more easily machined than alloy steels.
Table 3 highlights the comparisons between alloy steel and carbon steel:
Alloy steels vary in thermal conductivity but are generally less conductive than carbon steels
Carbon steels have a higher thermal conductivity of about 45 W/(mK)
Alloy steels have higher tensile strength than carbon steels (up to 960 MPa)
Carbon steels have lower tensile strength (450 MPa)
Used in a variety of high-temperature applications, such as in petrochemical and power plants
Used in applications without particularly high temperatures
Below are some mutual alternatives to both alloy and carbon steel:
- Stainless Steel: Like both alloy and carbon steel, stainless steel does not readily corrode, rust, or stain with water. Stainless steel is an alloy involving carbon and chromium.
- Nickel Alloys: Nickel alloys contain steel and nickel to make them resistant to corrosion and oxidation. They can also handle high temperatures, making them ideal for use in power plants and chemical plants.
Alloy steels and carbon steels are both composed primarily of iron. They also contain small amounts of other elements, such as: carbon, manganese, chromium, molybdenum, and nickel. Both types can also be produced in a wide variety of grades, each with its own unique set of properties and characteristics. Both alloy steel and carbon steel are strong, hard, and durable. They can be heat-treated to increase their strength and hardness.
Listed below are some other materials that, depending on the application, may serve as stand-ins for carbon steel:
- Cast Iron: This metal is made by re-melting pig iron, usually with considerable quantities of scrap iron and sometimes with steel. It is generally used for making gray iron castings.
- Ductile Iron: Also called nodular cast iron, spheroidal graphite iron, or nodular iron, this is a variation of cast iron that has been treated with an element such as cerium or magnesium while molten. The process is done to induce the formation of free graphite as nodules in the metal matrix.
- Wrought Iron: This is an iron alloy with very low carbon content. It is a semi-fused mass of iron with fibrous slag additions (up to 2% by weight), which gives it a "grain" resembling wood that is visible when it is etched or bent to the point of failure.
- Beryllium Copper Alloy: This copper alloy contains 0.5-3% beryllium and sometimes other elements. Beryllium copper combines high strength with non-magnetic and non-sparking qualities.
- Aluminum Bronze: This is an alloy of copper with aluminum in varying proportions. Typical compositions are 8–12% Al, 0.5–3% Fe, and 89–91% Cu. It is strong and corrosion-resistant, finding use in marine applications.
- Brass: The proportions of zinc and copper in this alloy can be varied to reach different mechanical and electrical properties.
Listed below are a few other alternatives to alloy steel:
- Chrome Steel: A chrome Steel is created by plating a layer of chromium on carbon steel. It is highly corrosion-resistant and is used for applications that include: drills, tools, and utensils.
- Copper Steel: An alloy of copper and steel used in the manufacture of rail tank cars and bridges.
- Beryllium Steel: This alloy of beryllium and iron regularly appears in the aerospace industry for its high strength and low weight.
- Aluminum Steel: Aluminum can be alloyed with other metals to give it superior properties. Aluminum alloys include the 3003 aluminum alloy and the 3004 aluminum alloy. They are used in the production of cooking utensils, pressure vessels, beverage cans, and sheet metal fabrications.
- Magnesium Steel: An alloy of magnesium and steel, this material gets used in the automotive industry for its low density and high strength.
- Tungsten Steel: An alloy of tungsten and steel is regularly used in the manufacture of cutting tools and other wear-resistant parts.
This article presented alloy steel and carbon steel, explained what they are, and discussed the different uses of each. To learn more about steel materials, contact a Xometry representative.
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