Carbon Steels
Carbon steels are a type of steel where the main alloying component is carbon. According to the American Iron and Steel Institute, carbon steel is also defined as having no specific minimum content for elements such as chromium, cobalt, nickel, titanium or any other element added to obtain a desired alloying effect. The term "carbon steel" can also refer to steels that are not stainless steel.
The amount of carbon contained in this steel influences its tensile strength, hardness and other properties. As the carbon content increases, the steel becomes harder and stronger. However, it also becomes less malleable and more difficult to weld.
Approximately 85% of all steel used in the United States is carbon steel. This represents by far the largest percentage of steel production and the most diverse applications of any engineering materials.
Four Classes of Plain Carbon Steel
There are at least 2,000 different types of carbon steel. Plain carbon steels typically have carbon content in the range of 0.30 to 1.50 weight percent, plus trace amounts of manganese, phosphorus, sulfur, and silicon. These carbon steels can be broken down into four classes based on the level of carbon content:
- Low-Carbon Steel
- Medium-Carbon Steel
- High-Carbon Steel
- Very High-Carbon Steel
Low-Carbon Steel
Low carbon steel has a carbon content of about 0.30 weight percent. Considered as all-purpose steel, it is strong and resilient, yet easier and more economical to produce. As a result, it forms the bulk of the steel market, and most often used in construction, industry and the making of wire mesh partitions.
Also called mild steel, this variety is very versatile and manageable. Low carbon steel can be bended, twisted or shaped quite easily as its being welded. It possesses perhaps the best weld ability of all the carbon steels. Stainless steels and aluminum alloys compete with this type of steel in certain industries.
Medium-Carbon Steel
Medium carbon steel has a carbon content of between 0.30 to 0.45 weight percent. Many consider medium carbon steel to have the optimum level of carbon content, giving it a good balance of toughness and ductility, as well as strength and hardness.
Medium carbon steel is extremely popular and has numerous applications. They can be used as general-purpose steel, or modified to be used in stressed applications such as gears, pylons and pipelines.
High-Carbon Steel
With a carbon content of 0.45 to 0.75 weight percent, high-carbon steels can be challenging to weld. Preheating, post-heating, and at times heating during welding, become necessary to produce satisfactory welds and to control the mechanical properties of the steel after welding. They are generally not recommended for welding.
Although high-carbon steel possesses a high degree of strength and hardness, their ability to withstand shock loading is poor. As a result, these steels valued for their hardness, and used in making products such as blades, spring and collars.
Very High-Carbon Steel
With a carbon content of up to 1.50 weight percent, very high-carbon steels are used where hardness is required. Like high-carbon steels, they require heat treating throughout the welding process to maintain their mechanical properties.
As a result, they are generally not recommended for welding.
Remarkably strong, very high-carbon steels are resistant to rust or staining. They can also hold an edge with very little maintenance. They are often used to make truck springs, cutting tools and high-strength wires.
Article Published August 18th, 2010
Carbon Steel by MajorPartitions.com
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