Tuesday, August 23, 2011

Basic and High Grade Structural Steels

Structural steel include all steels not used for the production of tools. Ordinary structural steels are basic and unalloyed high grade steels used for buildings, bridges, containers, automobiles and machines on account of their tensile strength and elastic limits.

Sections, rods wire rods, flat pieces and forging, made of this class of steel may be used in welded, forged and boiled structural parts.

As the carbon content rises, tensile strength, hardness, harden ability and wear resistance increase. At the same time however, breaking stretch cold formability and notch toughness decrease. Machine characteristics, weldability and forgeability also worsen.

The elastic limit and strength, of these steels fall with rising temperature. This is why alloyed, so called high temperature resistant – steel are used at temperature above 300oC.

Quality Classes
Quality class is specified by the code number -2 and -3 at the end of the designation code. The quality class -1, Bessemer steel (Thomas Gilchrisl steel) is no longer produced.

The steel of group 3 differ from those of group 2, principally in that they must fulfill higher standards regarding resistance to brittle fracture.

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