Tensile testing, also known as tension testing, is a fundamental materials science test in which a sample is subjected to a controlled tension until failure. The results from the test are commonly used to select a material for an application, for quality control, and to predict how a material will react under other types of forces. Properties that are directly measured via a tensile test are ultimate tensile strength, maximum elongation and reduction in area.
specimens made from an aluminum alloy. The left two specimens have a round
cross-section and threaded shoulders. The right two are flat specimen designed
to be used with serrated grips.
tensile specimen is a standardized sample cross-section. It has two shoulders
and a gauge (section) in between. The shoulders are large so they can be
readily gripped, whereas the gauge section has a smaller cross-section so that
the deformation and failure can occur in this area.
shoulders of the test specimen can be manufactured in various ways to mate to various
grips in the testing machine (see the image below). Each system has advantages
and disadvantages; for example, shoulders designed for serrated grips are easy
and cheap to manufacture, but the alignment of the specimen is dependent on the
skill of the technician. On the other hand, a pinned grip assures good
alignment. Threaded shoulders and grips also assure good alignment, but the
technician must know to thread each shoulder into the grip at least one
diameter's length, otherwise the threads can strip before the specimen
In large castings
and forgings it is common to add extra material, which is designed to
be removed from the casting so that test specimens can be made from it. These
specimens may not be exact representation of the whole workpiece because the
grain structure may be different throughout. In smaller workpieces or when
critical parts of the casting must be tested, a workpiece may be sacrificed to
make the test specimens. For workpieces that are machined from bar stock, the test
specimen can be made from the same piece as the bar stock.