Published: Monday, 13 May 2013
Written by Super User
Occasionally we get asked this question and the short answer is that you can not say carbon steel the same thing as hardened steel.
Both are different by contents and applications.
Carbon steel, many times called plain-carbon steel, is steel where the main alloying constituent is carbon.
The AISI (American Iron and Steel Institute) says: “Steel is considered to be carbon steel when no minimum content is specified or required for chromium, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40 percent; or when 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.
The purpose of heat treating carbon steel is to change the mechanical properties of steel, usually ductility, hardness, yield strength, and/or impact resistance.
The hardening process itself involves heating a steel to its normalising temperature and then cooling it rapidly in a suitable fluid such as water, oil, or even air.
Hardened steel is a type of medium to hard plain carbon steel that has undergone heat treatment, quenching and further reheating. Components made of hardened steel have a hard exterior casing and a robust core, and include arbors, axles, link components, driving pinions, camshafts and cardan joints. Application areas of components made from hardened steel include transportation, energy generation and general mechanical engineering.