Carbon Steel vs Black Steel

Carbon steel:

Made of carbon and iron, carbon steel is high in strength and durability. Due to its high tensile strength and corrosion resistance, carbon steel is commonly used in various industries such as oil and gas, construction, and water treatment. The carbon content in the steel determines its quality, and the higher the carbon content, the stronger the pipe produced, which is suitable for high-pressure applications. Carbon steel is susceptible to corrosion, and blackening to become black steel is a process that forms a tough oxide coating that has some corrosion resistance. Carbon steel is also known for its affordability compared to other materials such as stainless steel or copper.

Black steel:

Black steel is a type of steel that has been blackened to have a dark, scaly coating of iron oxide on its surface, giving it a unique dark appearance. This type of pipe is also known as black iron pipe or black malleable iron pipe. Unlike other steel pipes that have a shiny silver-grey surface, black steel pipe has a dark matte surface, which makes it unique in terms of beauty and application. It is used in applications where galvanized steel is not required.

Difference Between Carbon Steel and Black Steel?

Chemical composition:

Both carbon steel and black steel are primarily made of iron and carbon. That's why they are very powerful. Although the two alloys have different percentages of carbon content, their composition is the same.

There are different classes of carbon steel. They are categorized by the percentage of carbon that is mixed with the base element, iron. The hardness and strength of carbon steel increase as the carbon content increases, but the plasticity decreases. Carbon steel is widely used in many fields because of its low cost and good workability.

Classes of carbon steel 

Carbon content %:
Ultra-high carbon steel 1.00 – 2.00
High carbon steel 0.60 – 0.99
Medium carbon steel 0.30 – 0.59
Low carbon steel 0.16 – 0.29
Mild carbon steel 0.05 – 0.15

Black steel refers to ordinary carbon steel materials that are not galvanized or coated. The main components are iron and carbon. They appear black because the surface has not been treated. Black steel is an alloy steel with carbon as the main component, containing 0.3% to 1.7% carbon. It is suitable for making parts that require strength and corrosion resistance.

Production process:
In terms of production technology, carbon steel needs to add appropriate elements, undergo a series of processes such as quenching and annealing to make the ideal product. The production of black steel is relatively simple and can be directly made by cold rolling or hot rolling.

Corrosion resistance:
Carbon steel is very susceptible to corrosive agents, including chlorine, bleach, strong acids, and even high-humidity air. This is because these corrosive agents or moist air react with the carbon atoms within the carbon steel.

Black steel is resistant to corrosion and wear due to the high magnetite content on its surface. This is why black steel is often used in applications such as pipes that may require contact with corrosive agents.

Strength:
Both steels are very high in terms of structural strength and have similar characteristics in terms of weldability, ductility and ductility. However, black steel has better welding capabilities.

Application areas:

Since carbon steel‌ and black steel are similar in hardness, strength, and longevity, they are primarily used in similar applications. They can be found in construction, consumer products, engineering, kitchenware, tools, and more.

Black steel pipe fittings are widely used in various industries such as machinery, construction, petroleum, chemical industry, electric power, etc. In construction projects, black steel pipe fittings are often used to build brackets, bridges, shelves, etc.; in the field of mechanical processing, black steel pipe fittings are usually used to make Bearings, tires, etc.

Black steel pipe's strength makes it ideal for transporting water and gas in rural and urban areas and for conduits that protect electrical wiring and for delivering high pressure steam and air. The oil and petroleum industries use black steel pipe for moving large quantities of oil through remote areas. This is beneficial, since black steel pipe requires very little maintenance. Other uses for black steel pipes include gas distribution inside and outside homes, water wells and sewage systems. Black steel pipes are never used for transporting potable water.

Read more: Which is Better Seamless Pipe or Welded Pipe?