Tensile strength of steel

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The tensile strength of steel is one of the important properties of materials used in engineering and manufacturing applications.

The assessment of the usefulness of a steel product in the technical field is based on the knowledge of its properties.

Along with the chemical and physical ones, it is also necessary to know the mechanical and technological properties. They provide us with indications on its behavior in operation, as well as on the processing possibilities.

The mechanical properties of a steel derive from a combination of: chemical composition, heat treatment and elaboration/processing process.

Tensile strength is the maximum mechanical tensile stress to which a test part can be loaded. If this resistance is exceeded, the material fails.

It is denoted σr (or Rm) and measured in N/mm2.

THE FORMULA FOR CALCULATING TENSILE STRENGTH IS:

σr = F/A

where

F – the maximum force to which the specimen is subjected when it is pulled;

A – initial cross-sectional area of ​​the specimen.

Each batch of steel and respectively each batch of finished products from the respective batch are subjected to mechanical analyzes and tests. These tests also include traction tests. This consists in applying, in general, until breaking, along the longitudinal direction of the sample, a stretching force, in order to determine the mechanical characteristics.

The tensile strength is measured using a tensile machine/tensiometer.

The tensile tests also allow the determination of the ductility characteristics of a material, namely the elongation at break and the elongation at break.

The limit stress state of the material is considered to be the state of stress that corresponds either to the beginning of breaking the material, or to the beginning of a physical process that for some reason is considered inadmissible, undesirable or dangerous.

Traction and compression are called axial stresses because the supports of the forces are directed tangent to the geometric axis of the bar. They differ only in the sign of specific efforts, tensions and elongations: positive for traction and negative for compression.