Properties of Steel
Steel is an alloy mainly composed of iron and carbon, the latter in a percentage not higher than 2.06%: beyond this limit, the properties of the material change and the alloy takes the name of cast iron.
The carbon particles present in the microstructure of the steel, under certain conditions, block the sliding of the dislocations, giving the steel better mechanical characteristics than those of pure iron.
Steels are alloys that are always hot plastic, that is to say forging, unlike cast irons.
In addition to carbon there may be some other alligating elements, in fact, based on the chemical composition, the steels can be distinguished in:
• non-alloy steels are steels in which the contents of the alloy elements fall within the limits indicated in table I of EN 10020;
• alloy steels are steels for which at least one indicated limit of the aforementioned table I is exceeded.
By convention, alloy steels are subdivided into:
• low-alloy: no element above 5%,
• high-alloy: at least one alloying element above 5%.