What is Carbon Steel?

Carbon steel is basically iron mixed with carbon, and sometimes other elements are added to make it stronger and more useful. It’s used in everything from tall buildings to everyday tools, making it a key part of many things we use. Let’s look at what carbon steel is, the different kinds, and why it’s so important.

In this article, we’ll explain carbon steel, a common material used in many industries, from construction to manufacturing. 

Carbon steel, primarily composed of iron with a carbon content of up to 2.5%, is a critical material in various industries, particularly in oil and gas. In fact, over 80% of components used in the oil and gas sector are made from carbon steel. 

As an iron-carbon alloy, carbon steel can include small amounts of other elements such as manganese, silicon, sulfur, and phosphorus, which are typically present due to the steel-making process. These incidental elements do not significantly alter the mechanical properties of the steel. Instead, the primary characteristics of carbon steel are derived from its carbon content. By adding a small amount of carbon to iron, the material trades off some ductility for increased strength.

Carbon steel is known for its remarkable strength and toughness, making it one of the most versatile ferrous alloys available today. Its mechanical properties are highly sensitive to carbon levels, which usually remain below 1.0 wt%. With thousands of alloys available, each with varying compositions and heat treatments, carbon steel continues to be a cornerstone material for a wide range of applications.

Carbon steel is categorized into three types based on its carbon content: low-carbon steel (or mild steel), medium-carbon steel, and high-carbon steel. Each type differs in carbon content, microstructure, and properties, as outlined below.

• Strength and Durability – Carbon steel is known for its high strength and durability.
• Corrosion Resistance – Offers properties that resist corrosion, especially with protective coatings.
• Temperature Resistance – Functions effectively in both high and low temperatures.
• Variety of Types – Available in numerous types to suit different applications.
• Cost-Effective- Provides long-lasting performance at a reasonable cost.
• Eco-Friendly – Fully recyclable and environmentally friendly.
• Low Maintenance – Requires minimal upkeep and is easy to clean.
• Attractive Finishes – Can be finished for a pleasing appearance that resists tarnishing.

Carbon steel is primarily an alloy of iron and carbon, with carbon content ranging from 0.05% to 2.1% by weight. The American Iron and Steel Institute (AISI) specifies limits for other elements in carbon steel as well.

In the mechanics of materials, the strength of carbon steel refers to its ability to withstand applied loads without failure or plastic deformation. It involves examining the relationship between external loads on the material and the resulting changes in dimensions or deformation. Essentially, strength indicates how well carbon steel can endure these loads without compromising its integrity.

Process annealing is a method used to relieve stress in cold-worked carbon steel with less than 0.3% carbon content. During this process, the steel is typically heated to a temperature range of 550 to 650 °C (1,000 to 1,200 °F) for about one hour. In some cases, temperatures may reach up to 700 °C (1,300 °F). This treatment helps restore ductility and reduce internal stresses caused by cold working.

Carbon steel can be made from recycled steel, new steel, or a mix of both.

The process starts by mixing iron ore, coke (a material made by heating coal without air), and lime in a blast furnace at around 1650°C. The coke adds carbon to the molten iron, while the lime helps remove impurities, which form a layer of slag on top.

The molten steel initially has about 4% carbon. To get the right carbon level, a process called decarburization is used. Oxygen is blown through the steel to burn off the extra carbon, turning it into carbon monoxide and carbon dioxide.

The Brinell hardness of low-carbon steel is about 120 MPa.

In materials science, hardness measures a material’s resistance to surface indentation, scratching, and other forms of localized plastic deformation. Hardness is important for engineering because materials that are harder usually resist wear, abrasion, and erosion better.

The Brinell hardness test is commonly used to measure this property. It involves pressing a hard, spherical indenter into the surface of the material under a specific load. For low-carbon steel, a 10 mm diameter steel ball is typically used with a force of 3,000 kgf. The size of the indentation is then measured, and the hardness is expressed as a Brinell hardness number (HB). This number is calculated by dividing the load by the surface area of the indentation.

Thermal properties describe how materials respond to changes in temperature and heat. As a material absorbs heat, its temperature increases and its dimensions may expand. Different materials react to heat in various ways, affecting their performance in different conditions.

• Strong and durable
• High pressure resistance
• Corrosion and temperature resistant
• Available in various types
• Affordable and long-lasting
• Recyclable and eco-friendly
• Low maintenance and easy to clean
• Customizable, attractive finish

Check out our related blog to learn more about – Carbon Steel Uses 

Carbon steel, made from iron and carbon, is a versatile material known for its strength, hardness, and adaptability. Its various types and properties, such as those measured by the Brinell test and its response to temperature changes, make it essential in construction, manufacturing, and tool-making. Knowing these aspects helps in selecting the right carbon steel for your needs, underscoring its significance in engineering and industry. For more information on carbon steel price, contact us.