According to GOST 380-50, steel is divided into two groups: group A, supplied according to mechanical qualities; In this group, the brand is characterized by mechanical characteristics, and group B, in which the same brands are characterized by a chemical composition. The chemical composition of steel brands according to Group B according to GOST 380-50.
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There are still arsenic in the steel deposits. However, the studies have shown that the mouse content of up to 0.28% does not affect the mechanical properties of steels. Since the chemical composition is quite unambiguously related to the mechanical characteristics, the acceptance of steels by one and other signs (by mechanical characteristics or chemical composition) leads, generally speaking, to one results. However, taking into account indicators of only one group, incompletely determines the required qualities. Thus, the close dependence of coldnolism on the content of phosphorus and redness on the content of sulfur and the well -known difficulties of direct determination of the strength and tendency of the material to the formation of cracks at reduced or increased temperatures have long been in parallel with mechanical characteristics in group A to demand restrictions on Sere and phosphorus according to group B according to group B. The development of welded structures and the worst welding of steels with a high carbon content led to the requirement of restrictions on carbon content, and finally, for a number of structures of the use of calm steel and the simplest determination of the deigned (calm) steel by the amount of silicon (although this definition is not quite accurate) established the desirability of determining silicon; Thus, from the elements of the chemical composition determined by group B, one manganese was left without special restrictions; However, a large amount of manganese (exceeding the amount in group B) reduces the shock viscosity at normal temperatures and resistance against corrosion and, increasing hardness, complicates the processability of steel; a small amount of manganese reduces strength. Therefore, the fixation of manganese is appropriate. As a result, the idea arises of the comprehensive acceptance of construction steel in groups A and B at the same time division of brands into calm and boiling steel. These considerations are taken into account in the new proposal of the TSC “Steel for construction”.
