Monday, December 26, 2011

Designating Steel

Classification of Steels:

In the Euronorm, steels are classified according to their chemical composition and their characteristics as working materials.

Classification as per alloying components:

Unalloyed steels.
The content of various alloying components specified in the table should be less than the limits specified.

Alloyed Steels.
The percentage content of at least one of the elements specified, should be equal to or greater than the limit specified.

Classification according to working characteristics:
Basic steels are steel of low purity and uniformity of grain structure. They are unalloyed and not intended for heat treatment (quenching and tempering/surface hardenning).

High grade steels are purer and of better surface quality than basic steels. They may be alloyed or unalloyed. Unalloyed high-grade steels are ordinary structural steels which can be folded and cold formed, steel rods and rod wires which can be drawn and sheets which can be deep-drawn. Alloyed high-grade steels are fine-grain structural steels with high elastic limits. They are used as free cutting steels for sheets, strips, spring and parts subject to wear.

Superrefined Steels are very low in non metallic inclusions. Unalloyed superrefined steels are suited to heat treatment. Alloyed  superrefined steels are fine grain structural steel with a guaranteed elastic limit of at least 420 N/mm2. They are used as structural steels, tool steels and steels with tailor made characteristics.

Designation of steel types
Designation was hitherto government by DIN 17006. These norms have been outdated. Untill corresponding ISO norms have been fixed, however, symbols for materials will continue to be based on the system specified in DIN 17006.

A complete characterisation consist of three parts specifying method of production, composition and treatment.

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