Medium-Carbon Steel: Uses, Composition, and Its Properties
Medium-carbon steel is a versatile alloy known for its balanced carbon content, typically ranging from 0.3% to 0.6%. Because of its particular makeup, it has a variety of useful qualities. It is the perfect material for producing items like gears, axles, and equipment because of its strength and longevity. The desired qualities of medium-carbon steel, including outstanding weldability and machinability, are obtained by a regulated heating and cooling procedure.
Iron serves as the principal ingredient in medium-carbon steel's basic chemical makeup, which also includes: carbon, manganese, and traces of other components. Toughness and resistance to wear and tear are imparted by this combination.
This article will discuss the many uses of medium-carbon steel, its importance across different industries, its characteristics, and applications.
Medium-carbon steel, often referred to as M2 steel contains approximately 0.30% to 0.60% carbon and 0.60% to 1.65% manganese. The term M2 steel denotes its specific composition and properties. Its chemical name is typically a combination of iron (Fe), carbon (C), manganese (Mn), and other alloying elements. The structure of medium-carbon steel consists of a crystalline lattice of iron atoms with carbon and manganese atoms interspersed. This composition allows medium-carbon steel to be quenched and tempered for increased strength. It is primarily used for manufacturing axles, couplings, shafts, crankshafts, forgings, and gears, while higher carbon content variants (0.40% to 0.60%) are employed in applications such as: rail axles, railway wheels, and rails.
Carbon steel production is the typical method used to create medium-carbon steel. The mining of iron ore is the first step in this complex process. After being recovered, the ore is subsequently melted down into pig iron in a blast furnace. Controlled amounts of carbon, typically ranging from 0.3% to 0.6%, and other alloying elements are incorporated into the molten pig iron to achieve the appropriate medium-carbon content. The alloy is then refined, and while doing so, it is cast into different shapes. When compared to low-carbon steel variants, this process produces medium-carbon steel that is stronger and harder.
High chromium concentration in stainless steel creates a barrier against rust and corrosion. On the other hand, carbon steel, which is rich in carbon, can rust and corrode when exposed to moisture. The corrosion resistance that chromium gives stainless steel makes a significant impact.
Medium-carbon steel normally costs between $500 and 720 per ton. However, these costs can change depending on the grade, the shape, and the state of the market. It's advisable to speak with specific vendors to get the most precise and recent pricing information.
No, medium-carbon steel is not considered a medium-alloy steel. Medium-carbon steel primarily contains iron and carbon (around 0.3–0.6% carbon) with minimal alloying elements, whereas medium-alloy steel contains a significant percentage of alloying elements like chromium, nickel, or molybdenum, enhancing its mechanical properties. In the classification of steel alloys, if a steel contains less than 8% alloying elements, it is typically labeled as low-alloy steel. Conversely, when a steel composition includes more than 8% alloying elements, it falls into the category of high-alloy steel.
To learn more, see our article on What is an Alloy Steel.
The following are various forms of medium-carbon steel:
4140 steel is a chromium-molybdenum alloy with a carbon content of 0.38–0.43%. It excels in strength, wear resistance, and toughness, even in cryogenic temperatures. Its good weldability and corrosion resistance, due to its higher chromium content, make it ideal for heavy machinery components like hydraulic cylinders and shafts.
To learn more, see our guide on What is 4140.
1060 carbon steel, with a carbon content of around 0.60%, is favored for high-hardness blades. It's perfect for cutting-focused knives. While more brittle than 1045 steel, proper tempering achieves the desired toughness. 1060 steel remains easy to sharpen and maintain.
1045 steel, featuring a 0.45% carbon content, offers moderate strength and hardness. It's easily machinable and weldable but lacks exceptional corrosion and wear resistance. Commonly used in parts requiring high strength or wear resistance, such as: shafts, axles, gears, and sprockets. Its cost-effectiveness and effective heat-treatability are advantages.
Medium-carbon steel, known for its strength and ductility, serves vital roles in various applications. It's used in the following:
- Railway tracks for durability.
- Train wheels to withstand heavy loads.
- Crankshafts for engines.
- Machinery parts in which a blend of strength and machinability is crucial.
Medium-carbon steel typically contains 0.3–0.6% carbon. Other significant elements include manganese (0.6–1.65%) and, in some cases, small amounts of silicon, phosphorus, sulfur, and traces of other alloying elements like chromium and nickel. Table 1 highlights the chemical composition of medium-carbon steel:
The carbon content of medium-carbon steel typically falls within the range of 0.3–0.6%. According to the Iron-Carbon Phase Diagram, hypo-eutectoid steels like medium-carbon steel, when the carbon percentage is less than 0.76%, exhibit specific microstructural transformations. Initially, at 0.3% carbon and 940 ºC, the alloy consists of a gamma (austenite) microstructure. Upon slow cooling, ferrite forms, resulting in an alpha and gamma microstructure. The percentage of ferrite increases, leading to the formation of pro-eutectoid ferrite. Further cooling leads to the conversion of austenite into pearlite, a lamellar structure. Hypo-eutectoid steels are known for their softness and ductility due to the presence of pro-eutectoid ferrite. The specific properties depend on the exact carbon composition and heat treatment.
The characteristics of medium-carbon steel are listed in Table 2 below:
It is typically magnetic
Machinability ratings for medium-carbon steel, such as 1045, range from 28–60%. This grade is in contrast to 1112 carbon steel, which acts as the benchmark and has a rating of 100%. A smaller percentage means that medium-carbon steel is harder and more resistant to wear, making it harder to manufacture effectively.
Medium-carbon steel exhibits notable characteristics:
- Good balance of strength and ductility.
- Suitable for heat treatment.
- Enhanced wear resistance.
- Moderate machinability.
No, medium-carbon steel is not the cheapest carbon steel. It tends to be more expensive than low-carbon steel because of the additional alloying elements present, which enhance its properties but also raise production costs.
To learn more, see our article on Carbon Steel.
No, medium-carbon steel is not rust-resistant by nature. Since it isn’t as corrosion-resistant as stainless steel or other coatings, it might corrode when exposed to moisture and oxygen.
Yes, medium-carbon steel can be welded. When welding medium-carbon steel, precautions like preheating, using a similar chemical composition filler rod, and post-weld cleaning are essential. Gas metal arc welding (GMAW) is commonly preferred due to its flexibility and heat transfer properties.
No, medium-carbon steel isn't intrinsically resistant to corrosion. When exposed to oxygen and moisture, it is vulnerable to corrosion. It can either be coated or alloyed to increase corrosion resistance.
Medium-carbon steel can exhibit increased brittleness compared to low-carbon steel due to its higher carbon content. However, the degree of brittleness can vary based on factors like heat treatment and alloying elements.
Yes, medium-carbon steel can be stronger and more resilient than stainless steel. However, due to its greater susceptibility to rust and less ductility, it may not be suitable for many applications.
To learn more, see our guide on the Characteristics of Stainless Steel.
Table 3 summarizes the thermal properties of medium-carbon steel:
Specific Heat Capacity
Coefficient of Thermal Expansion
10.8 x 10-6/°C
Here are the common forms of medium-carbon steel materials:
They are known for their high strength and wear resistance, making them ideal for applications such as: shafts, axles, and gears. The microstructure of medium-carbon steel bars often consists of a combination of ferrite and pearlite, contributing to their robust mechanical properties.
Medium-carbon steel sheets share a similar carbon content range as carbon steel bars. They offer moderate strength and formability, making them suitable for use in automotive panels and various structural components. The microstructure of these sheets frequently exhibits a mixture of ferrite and pearlite, providing a balance of strength and workability.
It stands out for its high tensile strength, making it particularly well-suited for applications involving springs and cables. As the drawing strain reaches ε = 6.4, medium-carbon ferrite-pearlite steel wire's tensile strength escalates significantly, rising from 750 MPa to 4,120 MPa.
Table 4 highlights some approximate equivalents for medium-carbon steel from different regions:
45# or 45G
Medium-carbon steel is favored in many industries for its advantages:
- It can be heat-treated to achieve the desired hardness and strength.
- Its low melting point allows for easy welding.
- Good machinability for intricate parts.
- Provides durability for heavy loads and wear resistance.
The disadvantages of using medium-carbon steel are:
- Brittleness at specific temperatures or pressure levels without proper treatment.
- Susceptibility to rapid rusting when exposed to moisture without protective coating.
- Higher cost compared to other steel types like low-carbon steels due to additional alloying elements.
High-carbon steel has a carbon percentage that ranges from 0.6% to 1.5%, while medium-carbon steel normally has a carbon content of 0.3% to 0.6%. High-carbon steel is better suited for applications needing exceptional strength but is more brittle than medium-carbon steel. Medium-carbon steel is suitable for a wide range of applications because it strikes a compromise between strength and ductility.
This article presented medium-carbon steel, explained it, and discussed its various uses and composition. To learn more about copper, contact a Xometry representative.
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