Global steel production touched 1.9 billion tonnes in 2023. Did you know a big chunk of that, around 90% comes from carbon steel grades? But what makes carbon steel so popular? This versatile metal forms the backbone of industries. It is strong, affordable, and versatile.
But why are there different types of carbon steel? Let’s see how different carbon steel grades stack up against each other. This will help you select the right material for your project.
What is Carbon Steel?
Carbon steel is an alloy of iron and carbon. During production, carbon is added to molten iron to create steel. Its mechanical properties depend on the amount of carbon present, ranging from 0.04% to 2.5%.
Higher carbon content increases strength and hardness. However, it reduces weldability and ductility. Through heat treatment, carbon steel can achieve even greater toughness. It is also more cost-effective compared to many other metals.
Carbon steel is divided into three categories:
- Low-carbon steel
- Medium-carbon steel
- High-carbon steel
Each type has unique properties and uses.
Low Carbon Steel
Low-carbon steel has a lower carbon-to-iron ratio than other types. Its carbon content ranges between 0.05% and 0.32% by weight. Because of the low carbon levels, it is softer and more ductile than high-carbon steel. Small amounts of silicon and manganese are also added. These elements improve strength and offer light corrosion resistance.
The main purpose of low-carbon steel is flexibility and durability.
Properties
Here are some unique properties of low-carbon steel grades.
Ductile
Low-carbon steel is extremely ductile. It can stretch into different shapes without breaking. It can elongate 20% to 30% before snapping.
Welds Easily
Low-carbon steel welds easily. Minimal carbon means less risk of wrapping during the process. It is ideal for fabrication and structural projects.
Strong
Low-carbon steel maintains a strong structure while staying lightweight. Its density supports both durability and easy handling.
Easy Machinability
Its low melting point benefits forging, welding, and shaping processes.
Thermal Conductivity
Low-carbon steel conducts heat moderately. It diffuses energy well. That makes it perfect for cookware and heating equipment.
High Tensile Strength
Low-carbon steel has high tensile strength. It can withstand pulling forces. Its yield strength is moderate, allowing flexibility under stress.
Properties | Values |
Density | 2.85-8.08 g/cm3 |
Shear modulus | 10200-11600 ksi |
Melting point | 2600°F |
Fracture toughness | 30.0 – 105 ksi-in½ |
Tensile strength | 400-550 MPa |
Yield strength | 200-300 MPa |
Thermal conductivity | 25.3-90 W/m-k |
Types of Low-Carbon Steel
Low-carbon steel comes in various forms. Each type is suited for different applications.
Low-carbon Structural Steel
This type is used in construction and structural projects. It offers stiffness and durability. Carbon steel grades in this category are perfect for building bridges.
Low-carbon Sheet and Strip Steel
This steel is available in coils, sheets, and strips. It is ideal for applications requiring thin, flat surfaces. Carbon steel grades in this form are flexible and easy to shape. Common uses include vehicle parts, air conditioners, and electronics. The thickness ranges from 0.18 mm to 4.50 mm.
Low-carbon Tubing and Piping Steel
This steel stays strong under high temperatures and pressure. It is important in chemical plants, underwater oil pipelines and water treatment facilities. It is crucial in maintaining safety and performance.
Low-carbon Pressure Vessel Steel
This steel is designed for heavy equipment and machinery. It is ideal for boilers and pressure vessels. Carbon steel grades in this category are built to withstand high internal pressures.
Low-carbon Galvanized Steel
It is coated for protection. This low-carbon steel is durable and resistant to corrosion. It is used in roofing, automotive body panels, and HVAC systems.
Low-Carbon Steel Grades
Each carbon steel grade is defined by its distinct properties. These are influenced by factors like chemical composition and heat treatment. Here are some commonly used low-carbon steel grades:
Standard | Grade | Usage |
ASTM A36/A36M | A36 | Buildings, bridges |
ASTM A513/A513M | 1010 | Automotive parts |
SAE J403 | 1006 | Wire products |
ASTM A53/A53M | B | Water and gas pipelines |
SAE J403 | 1008 | Sheet metal work |
SAE J403 | 1010 | Sheet metal work |
ASTM A516/A516M | 70 | Boilers and pressure vessels |
AISI/SAE | 1018 | Shafts, spindles, and mounting plates |
ASTM A1011/A1011M | 33 | Automotive and agricultural equipment |
Comparison Between 1018 and A36 Carbon Steel
Both 1018 and A36 are popular carbon steel grades. 1018 is a cold-rolled steel. A36 is a hot-rolled steel. Their properties differ in strength, surface finish, and machinability. Here is a quick comparison of the carbon steel grades:
Property and content | 1018 steel | A36 steel |
Tensile strength (psi) | 63,800 | 58,000-79.800 |
Yield strength | 53,700 | 36,300 |
Elongation | 15% | 20% |
Iron | 98.81% – 99.26% | 99% |
Carbon | 0.18% | 0.26% |
Manganese | 0.60% – 0.90% | 0.75% |
Phosphorus | 0.04% max | 0.04% max |
Sulfur | 0.05% | 0.05% |
Copper | – | 0.20% |
Medium-carbon Steel
Medium carbon steel blends strength and toughness in a perfect balance. It contains between 0.3% to 0.6% carbon. This higher carbon level gives it more hardness than low-carbon steel. But it also makes it less flexible. Forming and welding need extra effort.
Medium carbon steel contains manganese, too. Manganese levels range from 0.60% to 1.65%. This adds even more strength and hardenability. Because of these traits, medium carbon steel is trusted for heavy-duty parts. It stands strong where both strength and wear resistance matter.
Properties
Medium carbon steel strikes a fine balance between strength and flexibility. Its properties depend heavily on carbon levels and other alloying elements.
Tensile Strength
It offers higher tensile and yield strength than low-carbon steel. Hard carbide particles form inside the structure, acting like tiny reinforcements. This makes steel tougher and harder to bend or break under pressure.
Ductility
Although medium carbon steel is tough, it can still bend, shape, and form without cracking. It absorbs shocks well, making it ideal for parts that face heavy impacts.
Machinability
Thanks to its carbon content and small amounts of manganese or sulfur, it cuts cleanly. Machines can shape it easily, creating smooth finishes and accurate parts.
Heat Treatability
Heat treatability gives it even more versatility. Processes like quenching and tempering can boost hardness.
Weldability
The weldability of medium carbon steel is trickier than low carbon steel options. Without preheating or using proper techniques, cracks might occur.
Properties | Values |
Melting point | 1420 – 1460 °C |
Machinability | 40.0 – 80.0% |
Tensile strength | 420 Mpa |
Hardness | 200 Mpa |
Density | 7.75 – 7.89 g/cm³ |
Thermal conductivity | 21.9 – 52.0 W/m-K |
Shear modulus | 72.0 – 82.0 GPa |
Fracture toughness | 80.9 – 143 MPa-m½ |
Modulus of elasticity | 187 – 213 GPa |
Medium-carbon steel grades
Let’s explore some common grades of medium-carbon steel
4140
This grade blends chromium and molybdenum with 0.38-0.43% carbon. It delivers exceptional strength. It resists wear and corrosion better than many other carbon steel grades. You will often find it in hydraulic cylinders, shafts, and heavy machinery parts. Its weldability is another bonus, making fabrication much easier.
1045
With 0.45% carbon, 1045 steel offers a fine mix of toughness and workability. It is easier to machine and weld than 4140 or 1060. However, it lacks the strong corrosion resistance of higher alloys. It is ideal for crafting rockets, gears, axles and shafts.
Each of these carbon steel grades brings unique strengths to the table.
Common Forms of Medium-Carbon Steel
Medium carbon steel comes in different forms. Each suits a specific need.
Bars
Bars are a popular choice. They come in cylindrical and rectangular shapes. They are ideal for manufacturing heavy-duty shafts, axles, and gears. Many bars also bend pearlite and ferrite to boost durability. Bar stock is a top pick for CNC-machined parts.
Sheets
Sheets are another common form. They are widely used in making automotive panels and structural parts. They are easy to mould, form, weld, and machine. These sheets handle tough jobs without cracking. Like bars, sheets often contain pearlite and ferrite for added strength.
Wire
Medium carbon steel grades are used for crafting springs, cables, and other products needing both toughness and bendability. Even when twisted or bent, medium carbon steel wire holds its shape. It remains strong under pressure, making it a trusted material in demanding industries.
High-carbon steel
High-carbon steel holds between 0.60% and 1.5% carbon. It also contains 0.30% to 0.90% manganese. This type stands out for its incredible hardness and strength. The higher carbon boosts its wear resistance, making it perfect for tough environments. Its natural toughness gives it an edge over other steels in durability.
Yet, this strength comes at a cost. High-carbon steel tends to be brittle. It can crack under sudden force or stress. Flexibility is not its strong point. Moreover, special care is needed during fabrication.
Properties
Here are some noteworthy characteristics of high-carbon steel.
Hardness
High-carbon steel is known for its outstanding hardness. The high carbon content binds with iron to form strong carbides. This structure increases both hardness and overall strength.
Strength
High carbon steel shows excellent strength after heat treatments like oil and water quenching. These processes enhance hardness and improve tensile strength. As a result, high-carbon steel performs well under heavy loads.
Wear resistance
The hard surface withstands friction and abrasion effectively. This makes it ideal for hammerheads, blades, and industrial needles.
Risk of Cracking
Higher carbon content improves hardness but also increases the risk of cracking. Careful handling during manufacturing and usage is essential to prevent breakage.
Properties | Values |
Melting point | 1540 – 1590°C |
Density | 0.451-8.26 g/cc (0.0163 – 0.298 lb/in³ ) |
Tensile strength | 161-3200 MPa |
Shear modulus | 78.0 – 82.7 GPa |
Machinability | 10.0 – 125% |
Thermal conductivity | 19.0 – 52.0 W/ m-k |
Modulus of elasticity | 13.8 – 235 GPa |
Fracture toughness | 13.2 – 165 MPa-m½ |
Hardness | 43.0 – 100 |
Types of High-Carbon Steel
High carbon steel grades come in several specialized types, each built for tough performance.
Plain Carbon Steel
Plain carbon steel is the simplest. It blends iron with trace elements like manganese and silicon. Known for its strength and affordability, it handles harsh conditions well. You will find it in bridges, buildings, and other heavy structures.
Alloyed Carbon Steel
Other trace elements are added to raise their toughness, like:
- Chromium
- Cobalt
- Molybdenum
- Nickel
- Tungsten
- Vanadium
It gains better rust resistance. It is a favorite for automotive parts and heavy-duty tools that demand lasting power.
Spring Steel
It stands apart with its flexibility. It contains 0.6 to 1.0% carbon with silicon. This mix gives it high-yield strength, making it perfect for springs and resilient parts.
Tool steel
Packed with elements like tungsten and molybdenum, it shows extreme hardness. This toughness makes it ideal for drill bits and saw blades.
High-Carbon Steel Grades
Each carbon steel grade falls under a specific standard. Here are some of the most widely used grades of high-carbon steel:
Standard | Grade | Usage |
ASTM A29/A29M | 1060 | Springs, gears, and axles |
ASTM A29/A29M | 1065 | Springs and cutting tools |
ASTM A29/A29M | 1070 | Automotive suspension components |
ASTM A29/A29M | 1080 | Heavy machinery parts |
ASTM A295 | 52100 | Ball and roller bearings |
The two most popular high-carbon steel grades are 1060 and 52100. Let’s compare them side by side.
Properties | 1060 | 52100 |
Melting point | 1540–1590ºC | 1424–1460ºC |
Density | 7.85 g/cm² | 7.81 g/cm² |
Machinability | 45 to 57% | 50% |
Yield strength | 485 MPa | 2033 MPa |
Thermal conductivity | 19.0 – 52.0 W/ mk | 46.6 W/m.k |
Hardness | 89 | 64 |
FAQs
Is medium-carbon steel more expensive than low-carbon steel?
Yes, medium-carbon steel is generally more expensive. This is due to its higher strength, more alloying elements, and complex manufacturing process.
Is high-carbon steel more brittle than low-carbon steel?
Yes, high-carbon steel is more brittle and harder to work with than low-carbon steel. However, it offers superior strength and wear resistance.
How does carbon content affect steel properties?
Higher carbon content increases hardness and strength but reduces ductility. The right carbon level depends on the application’s needs.
Conclusion
Carbon steel is the backbone of industries. Understanding carbon steel grades ensures smarter decisions in construction and manufacturing. Choosing the right grade depends on strength, flexibility, and cost needs. From flexible low-carbon steel to tough high-carbon steel, each type has its unique spot. Call us to get a favourable price.
