What is carbon steels ?

Carbon steel is a steel with carbon content from about 0.05% up to 3.8% by weight. 

The definition of carbon steel from the American Iron and Steel Institute (AISI) states:

1.No minimum content is specified or required for chromium, cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium, zirconium, or any other element to be added to obtain a desired alloying effect;

2.The specified minimum for copper does not exceed 0.860%;

3.The maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65%; silicon 0.60%; copper 0.60%.

Type

Low-carbon steel

0.05 to 0.25% carbon (plain carbon steel) content.

Medium-carbon steel

Approximately 0.3–0.5% carbon content. Balances ductility and strength and has good wear resistance; used for large parts, forging and automotive components.

High-carbon steel

Approximately 0.6 to 1.0% carbon content. Very strong, used for springs, edged tools, and high-strength wires.

Ultra-high-carbon steel

Approximately 1.25–2.0% carbon content. Steels that can be tempered to great hardness. Used for special purposes like (non-industrial-purpose) knives, axles or punches. Most steels with more than 2.5% carbon content are made using powder metallurgy.