alloy of iron and carbon with the content of the latter is not more than 2.14% is called steel.The main qualities are: strength, plasticity, viscosity, elasticity, durability and others.The main classification of steel is determined by:
- chemical composition.
- structural composition.
- quality of steel or alloy (depending on the amount of harmful impurities and method of production).
- degree of deoxidation.
- destination.
chemical composition
Depending on the amount of carbon in the alloy composition distinguish carbon and alloy steels.The carbon content of both types of steel and determines their marked and GOST mark.Classification carbon steels subdivided into:
- Mild (content C (carbon) is less than 0.3%).
- sredneuglerodistoj (content of C - from 0.3 to 0.7%).
- High-carbon (content of C - higher than 0.7%).
order to improve the processability of the alloy, alloyed steel.The alloy is introduced other than the main components and additives, special chemical elements (nickel, chromium, molybdenum, aluminum, boron, vanadium, thallium, etc.) that provide an integrated doping.In turn, the classification of alloy steels highlights:
- Low alloy (containing less than 2.5% of the components of alloy steel).
- srednelegirovannoj (containing from 2.5 to 10% of the components of alloy steel).High alloyed
- (containing above 10% of the components of the alloying steel).
Classification of steels for structural composition
Steel passed the doping process, divided into classes according to the structural composition.The structure of the alloy depends on the carbon content in the alloying components and the cooling rate after heating to 900 ⁰S.There are five types of structural composition:
- pearlitic alloy.
- martensitic alloy.
- austenitic alloys.
- Ferritic alloy.
- carbide alloy.
Classification of steels quality
production conditions (method of smelting, impurity content) of steel and alloys can be divided into several categories:
- ordinary quality (content of S (sulfur) & gt; 0,06%, P (Phosphorus) & lt; 0,07%).
- quality (content of S (sulfur) & gt; 0,04%, P (phosphorus) & lt; 0,35%).
- High (content S (sulfur) & gt; 0,025%, P (phosphorus) & lt; 0,025%).
- particularly high (the content of S (sulfur) & gt; 0,015%, P (phosphorus) & lt; 0,025%).
to steel of ordinary quality are carbon, cost and technological characteristics which are significantly inferior steels other classes.
The chemical composition of a species may be qualitative as alloyed and carbon steels.In the production of quality steels comply with more stringent requirements for the construction.
Carbon steels of ordinary quality, and quality are determined by the degree of hardening of deoxidation and character as a quiet, semi-killed and boiling.
High quality and high-quality steel have high technological characteristics, increased the degree of purification of contaminants.
Classification of steels intended
By appointment steel is classified into:
- Instrumental.
- constructional.
- steel with special properties.
