Ultimate tensile strength

The tensile strength ( ultimate tensile strength Sheet UTS ) is the voltage that is calculated from the relative maximum tensile force reached in a tensile test on the original cross section of the sample.

The read out of the stress-strain diagram of the voltage values ​​(tensile strength, yield strength ) do not correspond to the true stress in the material. This is because when calculating the tension, the tensile force is based on the initial cross-section. The actual cross-section but in the tensile test is less than the output cross-section ( transverse contraction, constriction ). In an elastic-plastic deformation ( in samples of ductile materials ), this deformation ( extension and contraction ) after the test is visible and measurable. Often is "true" distinction between the voltage and the " nominal" voltage ( " engineering stress ").

Nominal tensile strength so is not the true stress in the sample at the moment of the breakdown, but is smaller.

The true maximum stress occurs in the necking of the sample. In this region, increases the deformation and solidification at best to break. The so-called instrumented tensile test the sample cross-section is continuously measured and the force in relation to the true cross-section. For samples tested show a continuous increase in the true stress to fracture. The value determined in this way is only of theoretical importance.

The tensile strength has been widely used in the past for the characterization of materials. An example of this is the name of structural steels. Thus, the steel 52 ( ST52 today S355 ) denoted by its tensile strength of 52 kgf / mm ² ( 510 N / mm ²). Due to the harmonization of European and international standards today has the designation of many steels after the yield point, which is from a constructive point of view a better parameter for the load capacity of a material.

Typical numerical values: