Carbon steels
Carbon steel contains traces of alloying elements, iron and carbon. They represent 90% of the total steel production. They can be classified, in turn, according to the carbon content:
a) Steels with low carbon content, up to 0.3% carbon. The largest category of this class of steel is made up of flat rolled products (sheets or strips) usually in a cold rolled state. It is the most common form of steel, because its price is relatively low and it has acceptable properties for several applications.
b) Steels with medium carbon content, have between 0.3 and 0.6% carbon. The increase in the carbon content to approximately 0.5%, accompanied by an increase in the manganese content, allows this type of steel to be used in a hardened and tempered state. It has good resistance to wear and is used for large parts, drilling and car components.
c) Steels with a high carbon content, between 0.6 – 1 % carbon. Used especially for high resistance threads.
d) Steels with a very high carbon content, 1-2%. They are used for hard steel products such as metal cutting tools and truck springs.
Carbon steel – its properties
In general, increasing the amount of carbon reduces the ductility, but increases the tensile strength and the ability to harden by hardening. In the rolling process, carbon is added to the iron to strengthen its structures and to strengthen the resulting metal. The amount of added carbon changes the properties of the steel.
Low steel is very ductile. Used to produce flat rolled steel sheets and strips, which are used to build ships, car bodies, wire products, household appliances, sheet metal. Due to the low amount of carbon, this steel is usually more malleable than other types of steel. As a result, it can be thinly laminated into products, resulting in body panels for example. The carbon content used for these panels is usually less than 0.10%. And for products such as structural steel laminated plates usually up to 0.3%. Pipes made of this type of steel are used to transport substances, such as gas and oil.
Increasing carbon content
The higher carbon content makes steel harder, but reduces weldability, ductility and makes it more brittle.
Medium carbon steel is easier to process, and some manufacturers add a little silicon and manganese to improve the quality of the steel. It is ductile and hard, with good wear properties. This type of steel is more ductile than high carbon steel and less malleable than low carbon steel. Medium carbon steels have good wear resistance, so they are often used for auto parts and similar applications. They are also used in forging and for the production of large parts.
A steel with a high carbon content has higher tensile strength, but is less ductile and malleable than steel with a low and medium carbon content. It is very hard and has good shape memory making it ideal for springs and wire. It is also used for the production of high strength yarns.
Because it is quite fragile, steel with a high carbon content is not suitable for cold working. It can be heated and pressure treated to become exceptionally hard. This type of steel is used to create components that require extreme hardness, requiring special handling.
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