How Do Carbon Levels Affect Steel Quality?

15 February 2021

One material that is being maximised by numerous industries is steel. It is an alloy of iron that is typically comprised of a few per cent of carbon which can modify its general properties and composition. But generally, this specific material is durable enough to sustain damages from surrounding elements. And compared to other materials, steel has been known for its cost-efficiency due to its cheaper production requirements. It is also recyclable and environmentally friendly.

The addition of other elements allows the steel to be versatile, making it effective in producing machines and tools. Steel can also be utilised in constructing buildings and other structures.

Understanding How Carbon Affects Steel

What makes steel unique and special is its overall carbon composition. Without the integration of carbon, the iron would stay soft, which makes it impossible to be utilised in products that are needed by high-demanding industries. By adding small amounts of carbon, the iron will finally be converted into steel.

With the addition of carbon, the steel material is expected to obtain improved hardness and strength. However, the same element can also increase the brittleness of the steel. It can even reduce the weldability of steel since the presence of carbon allows the material to form martensite, which is a very hard and very brittle form of steel crystalline structure.

Most of the steel materials that are used today have less than 0.35 per cent carbon. A few steel materials have up to 2 per cent carbon, but they are not utilised widely.

General Classification of Steel Materials

The steel can be generally classified according to their content. Three of the most common types of steel are plain carbon steels, low-alloy steels, and high-alloy steels.

  • Plain Carbon Steels: Plain carbon steels usually have less than 1 per cent carbon. They are also comprised of small amounts of manganese, phosphorus, sulphur, and silicon. Plain carbon steels that have a carbon content of less than 0.30 per cent can be easily machined and welded, while those that have more than 0.30 per cent carbon have increased hardness and tensile strength.However, they tend to be more challenging to process and weld.
  • Low-Alloy Steels: Low-alloy steels usually have 0.15 to 0.25 per cent of carbon content. This type of steel normally has nickel, chromium, molybdenum, manganese, and silicon. These elements allow low-alloy steels to obtain improved strength at room temperatures and increased low-temperature notch toughness. They can also effectively resist corrosion of low-alloy steels. 
  • High-Alloy Steels: High-alloy steels, which are mostly known as stainless steels, are products that are often used in commercial industries. They usually have 12 per cent chromium and a high percentage of nickel. High-alloy steels can be austenitic, ferritic, and martensitic. Austenitic stainless steels can offer excellent weldability, while ferritic steels are known for their heat and corrosion resistance. Martensitic stainless steels, ultimately, offer high hardenability.

Work with Alpha Detroit Heat Treatment

To know more about steels and their processes, feel free to contact us at Alpha Detroit Heat Treatment. We aim to offer the widest range of specialty heat treatment services for complex engineering projects and to play a key role in the manufacturing of parts for all industries in Australia and New Zealand.

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