Low Carbon Steel: Properties, Grades, and Key Applications

Carbon steel, a popular material, has various grades and types to serve different functions. One such type is Low Carbon Steel. Let’s explore why it’s named so, its properties, and what makes it unique. To understand its importance, let’s explore its characteristics.

What is Low Carbon Steel

Steel alloy that consists of 0.05% carbon to a maximum of 0.3% carbon is classified as low carbon steel. It is also known as soft steel or neutral steel. Additionally, small amounts of silicon and manganese are also added to offer some corrosion resistance. However, the main function of low carbon steel is to provide flexibility and ductility.

Low Carbon Steel Properties

Ductility

Ductility means a material’s ability to stretch without breaking. Usually, materials with high ductility can be pulled and made into various shapes.

Low carbon steel has high ductility due to its low carbon content. It also has ferrite as microstructure, which makes it soft and flexible.

It makes it resistant to cracking and high elongation at break. This means low carbon steel can stretch up to 20-30% of its original length before failing.

Weldability

Weldability means the ability of steel to perform under heat and pressure to join together. This property is essential for making a proper structure using steel.

Low carbon steel is weldable in nature due to its minimal carbon content, which allows for welding without warping.

Density

Density enables steel to maintain structural integrity, despite being lightweight. Low carbon steel has a favourable density range.

Melting Point

Low carbon steel has a notably low melting point. This becomes beneficial for welding and forging processes.

Thermal Conductivity

Low carbon steel has a moderate thermal conductivity. It ensures efficient energy diffusion and minimises heat loss in cookware appliances.

Tensile and Yield Strength

Low carbon steel has high tensile strength so it can endure strong forces. But it has moderate yield strength, which limits its resistance to heavy loads.

Shear Modulus

Low carbon steel has moderate shear modulus. However, it can start to lose its shape and structures at constant shear stresses.

Properties	Specifications of Low Carbon Steel
Density	2.85-8.08 g/cm³
Tensile Strength	400-550 MPa
Yield Strength	200-300 MPa
Melting Point	1420-1460 ºC
Shear Modulus	70 – 80 GPa
Thermal Conductivity	25.3- 90 W/m-K

Types of Low Carbon Steel

Low carbon steel is available in various types, and the list of those types is given below.

Low Carbon Structural Steel

It is suitable for construction and structural projects.
It can offer high stiffness and durability.
Its major uses include building and bridge construction.

Low Carbon Sheet and Strip Steel

This type of steel comes in coils, sheets, and strip forms.
Applications that require thin material can use this, as it is renowned for thin and flat surfaces.
Very flexible to work with
Thickness range- 0.18 mm – 4.50 mm (IS 513)
Sheets and strips can be easily turned into desired shapes, which are useful for vehicle parts, air conditioners, and other electronics parts.

Low Carbon Tubing and Piping Steel

Tubing and piping steels can carry oils, water, and gases at high temperature and pressures.
They are made from steel sheets by rolling.
It is used in

-Chemical plants

-Underwater oil pipelines

-Water treatment plants

-Oil and petroleum refineries

These pipes and tubes can also be seamless without welds or joints.
Length of seamless pipe: 16 ft – 35 ft (ASTM A106 Grade B)
Thickness ranges from 3mm to 12 mm

Low- Carbon Pressure Vessel Steel Plates

It can endure heavy pressure and offers high strength
Commonly used in

-Boilers

-Pressure vessels

-Storage Tanks

-Heat exchangers

Length – 12.5 mm – 200 mm
Carbon content in these steel plates vary from 0.21 % – 0.3%
It shows excellent weldability and has high tensile strength from 415-620 MPa (ASTM A516)

Grades of Low Carbon Steel

There are various standards and grades for different types of low-carbon steel. These are governed by renowned organisations such as:

– ASTM International -American Society for Testing and Materials

– AISI -American Iron and Steel Institute

– SAE -Society of Automotive Engineers

These organisations establish international standards. Moreover, they drive innovation and quality in steel production and applications.

In India, BIS sets standards for steel products, which are known as Indian Standards. For example, IS standards specify grades for carbon steel sheet and strip.

Low Carbon Steel Sheet and Strip Specifications

Standard	Grade	Carbon %	Manganese %	Sulphur %	Phosphorus%	Titanium %
IS 513	CR1	0.15	0.60	0.035	0.050	–
	CR2	0.12	0.50	0.035	0.040	–
	CR3	0.10	0.45	0.030	0.025	–
	CR4	0.08	0.40	0.030	0.020	–
	CR5	0.06	0.25	0.020	0.020	0.15

Applications of Low Carbon Steel

Low-carbon steel is used in manufacturing car parts, because it has high flexibility and strength.
It has a thin, flat, and shiny surface, which is suitable for building frames.
Low-carbon steel can resist high pressure, so it’s widely used in oil and gas lines and industries.
The thin and flexible nature of low carbon steel is ideal for electrical wires.
Low-carbon steel is common in our home appliances, such as refrigerators, washing machines, and air conditioners.
Low-carbon steel is used for storage tanks, and it’s safe to use in containers carrying liquids and gases.

Advantages of Low Carbon Steel

It is inexpensive compared to other carbon steel types
Has high weldability. So it can be trimmed and joined to the desired shapes.
It has less risk of cracking and breaking.
It can be available in any form, such as tubes, pipes or sheets due to its malleable nature.

Disadvantages of Low Carbon Steel

It can lose its properties at high temperatures.
Low carbon steel has low strength and cannot bear heavy loads.
It is not completely rust-proof but has some resistance to corrosion
It is difficult to achieve accurate dimensions.

What is the Difference between Low Carbon Steel and High Carbon Steel?

Low carbon steel	High carbon steel
0.05-0.25 % of carbon	0.5 -1.5 % of carbon
It is softer and more flexible	It is harder, stronger and also brittle in nature
Can be easily stretched, twisted and turned into any shapes	Difficult to weld and shape
Ideal for general construction, vehicle parts and home appliances	Used for making cutting tools and high-strength products.

Conclusion

Low-carbon steel’s properties make it suitable for various applications surrounding us. It is recommended to follow standards when manufacturing and selecting low-carbon steel. Additionally, its affordability makes it a common material in construction and other purposes.