What is Carbon Steel? An Overview of its Types, Pros, and Cons

Introduction

We see steel all around us today. It is a valuable metal in manufacturing, construction, and electronics. From watches, belts, tables, and chairs to buildings and bridges. Steel is used everywhere, from everyday items to man-made structures. But you may not be aware that different varieties of steel are used in the industry today. These are known as alloys, and carbon steel is one such metal that is known for its strength and durability. Do you want to learn more about carbon steel and its benefits? Excellent, you have come to the right place.

Carbon Steel Explained

Carbon steel is an alloy metal formed by combining iron and carbon. The percentage of carbon in it can range from low (0.05%) to high (2%). You may think that such a small amount of carbon is insignificant, but it changes the properties of iron immensely. In contrast, other steels have a carbon content between 0.05% to 0.3%. Because carbon is the primary hardening material, this steel is strong, durable, flexible, and tough.

Types of Carbon Steel

Carbon steel comes in different compositions, known as grades. It exists in three distinct types: low-carbon, medium-carbon, and high-carbon steel. These categories represent the amount of carbon in the steel.

Low-Carbon Steel

Steel consisting of 0.05 to 0.25% carbon and the rest of pure iron is known as low-carbon steel. The low carbon content means that this steel is not very hard. It has many applications due to excellent malleability and ductility. You can also increase the surface hardness of low-carbon steel by heat treatment.

Despite offering low tensile strength, low-carbon steel has several useful properties. It is highly suitable for bending and welding operations. High-strength low-alloy (HSLA) steel is a form of low-carbon steel. Reinforced with metals like vanadium, nickel, copper, or molybdenum, it offers better physical properties. HSLA is resistant to cracking and offers greater corrosion resistance than other forms of carbon steel.

Low-carbon steel is highly machinable and offers other excellent mechanical properties. It is integral to the manufacturing, automobile, and furniture industries.

Medium-Carbon Steel

The carbon content in medium-carbon steels ranges between 0.3 to 0.6% by weight. It also has a small amount of manganese, ranging from 0.6% to 1.65%. The increase in the quantity of carbon and the introduction of manganese makes this steel suitable for some heat treatment processes. You will often find medium-carbon steel in quenched and tempered forms.

Medium-carbon steel has an altered martensite structure. It differs from low-carbon steel in several physical properties. Medium-carbon steel is harder than low-carbon steel, although this makes it less malleable and ductile. Medium-carbon steel is prone to hardening and cracking during welding. It is necessary to take some precautions before working with it. Pre-heating and using less hydrogen while welding can make the process smooth.

This steel finds great use in manufacturing and construction. You can find medium-carbon steel in railroad tracks, beams, bridges, and machine parts like axels, gears, and shafts.

High-Carbon Steel

Alloys with carbon content between 0.6% to 1% are known as high-carbon steels. They also have a manganese content of about 0.3% to 0.9%. They have the greatest hardness and tensile strength of all carbon steels. Due to their hard nature, high-carbon steels are less malleable, ductile, and tough. They are also unsuitable for welding operations, making them low in machinability.

High-carbon steels are hardened and tempered, which makes them greatly wear-resistant. Due to their extreme hardness, they are suitable for making cutting tools and equipment like knives, swords, and metal cutters. They are highly unsuitable for welding, however, due to the formation of brittle martensite structures during the cooling phase.

High-carbon steel tools and equipment display excellent temperature tolerance. You can find it in cutting tools, hammers, wrenches, screwdrivers, and springs.

Carbon Steel Grades

Carbon steel comes in many grades with different properties. It’s important to learn about these differences before buying steel.

1010 Carbon Steel

This is a low-carbon steel that contains 0.1% carbon by weight. It is low in tensile strength but has good ductility. 1010 carbon steel makes wires, nails, automobile panels, etc.

1020 Carbon Steel

Another low-carbon steel. It has better tensile strength and good malleability. It contains 0.2% carbon by weight. Sheet steel, structural steel, and pipes are some common applications of this.

A36 Carbon Steel

This low-carbon steel contains 0.29% carbon by weight. It is a primary component of buildings and structures. Commonly available forms include plates, bars, girders, etc.

A516 Grade 70 Carbon Steel

This metal is classified as a low-carbon steel. It contains about 0.3% carbon by weight. It also contains silicon and manganese. It is suitable for making low-temperature pressure vessels like boilers.

1030 Carbon Steel

This medium-carbon steel has carbon between 0.27 to 0.34%. It has good tensile strength and ductility. It can be hardened by heat treatment like quenching and tempering. It has good machinability after annealing. It serves in making bolts, axles, gears, and machine parts.

1040 Carbon Steel

1040 carbon steel is categorized as medium-carbon steel and contains 0.37 to 0.44% carbon. In addition, 1040 carbon steel consists of a small quantity of manganese. It has high tensile strength. 1040 steel also has good welding properties. The manufacturing of crankshafts, cold-headed parts, and couplings is carried out with 1040 steel.

1080 Carbon Steel

This is high-carbon steel containing 0.75 to 0.88% carbon. 1080 carbon steel offers great load bearing but has low workability. Due to excellent wear resistance and hardness, it is employed in making cutting tools, durable wires, and springs. It is not suitable for welding applications.

1095 Carbon Steel

Another high-carbon steel that contains about 0.90 to 1.04% carbon by weight. It offers the high tensile strength and the greatest hardness. Due to low ductility and machinability, it is used in making cutting tools and springs.

Applications of Carbon Steel

Structures and Construction

Medium to high carbon steels offer excellent tensile strength, hardness, and wear resistance. These are precisely the qualities needed for construction. They also possess good machinability, welding, and hot and cold forming properties. Carbon steel has several beneficial properties, excellent heat treatment capabilities, and affordable pricing. All this makes it exceptional at meeting the rigorous requirements of structural engineering. It can make diverse steel profiles and sections.

Petrochemical Wells

Steel that is in constant contact with petrochemicals is prone to hydrogen-induced cracking (HIC). Low-carbon steel that is desulphurized and dephosphorized is employed for this application. HIC-resistant carbon steel has an exceptionally pure composition that is resistant to hydrogen embrittlement and cracking.

Naval and Shipbuilding Applications

The excellent hot forming and flat rolling properties of carbon steel make it ideal for shipbuilding and naval use. It is used in conjunction with harder metals to form major shipping superstructures. Low-carbon steel complements the manganese-rich corrosion-resistant hull cladding in ships. Many ship parts have carbon steel as part of their foundation.

Pipes and Pressure Vessels

Due to the high weldability and malleability of low-carbon steel, it is often utilized in pipelines and pressure vessels. Through the process of carburization, carbon steel can be made hard and wear-resistant on the exterior. It retains the pearlite structure in its interior. This property of carbon steel is exceptionally useful in making high-pressure containers and pipes.

Pros of Carbon Steel

There is a reason why you see carbon steel across all industries. Here is a comprehensive list of its pros:

1. Carbon steel is hard, strong, and wear-resistant. It has high durability and is particularly useful in construction and manufacturing.

2. Low-carbon steel has excellent machinability and welding properties. Although medium-carbon steel is less ductile, annealing can increase its machinability.

3. Carbon steel is highly weldable. Most forms of low and medium-carbon steel can weld by any method.

4. It does not require much maintenance during its lifespan.

5. Carbon steel has excellent heat treatment properties. Chemical and heat treatment techniques enhance its physical properties. Quenching and tempering can increase the hardness of carbon steel.

6. Carbon steel is inexpensive and easily available.

Cons of Carbon Steel

Despite many strengths, carbon steel falls short in some aspects compared to other steel. It is necessary to understand the cons of carbon steel before investing:

1. Carbon steel does not contain chromium like stainless steel. This makes it susceptible to corrosion and rust.

2. Due to exceptional strength and hardness, carbon steel can prove to be difficult to shape. It is challenging to weld and machine steel with a high concentration of carbon.

3. The initial investment in producing carbon steel is high.

4. Bending and molding operations with carbon steel are challenging and can lead to cracks.

5. Producing and working carbon steel can generate costly waste. Due to forming difficulties, re-working may be required. Frequent changes increase the operation time and cost.

Conclusion

Carbon steel is an excellent choice whether you want to build machine parts, automobile panels, structures, or cutting tools. It is inexpensive and widely available. It is a versatile metal that responds well to several treatment methods like quenching, tempering, annealing, and carburization. These techniques can help you alleviate the weaknesses of carbon steel and modify it according to your needs. Its great versatility is the reason we see carbon steel almost everywhere. We would be glad to hear from you and help you select the best carbon steel. Our professional team is just a phone call away. Contact us to receive a quick and comprehensive consultation.