Tensile strength

Tensile strength is the ability of a material to withstand a pulling (tensile) force and refers to the breaking strength of a material when applying a force capable of breaking many strands of the material simultaneously, at a constant rate of extension/load. It is customarily measured in units of force per cross-sectional area. Tensile strength is the amount of load or stress that can be handled by a material before it stretches and breaks. As its name implies, tensile strength is the material’s resistance to tension that is caused by mechanical loads applied to the material. The ability to resist breaking under tensile stress is one of the most important and widely measured properties of materials used for structural applications.

The tensile strength is the maximum tensile stress that a material can be subjected to before failure, although the actual definition of failure usually varies according to the material’s type and design. Reduction in ductility and an increase in brittleness are associated with an accelerated corrosion rate, which in turn can change the failure of the material from a ductile failure to a much more dangerous brittle failure.

The concept of tensile strength is of utmost importance in engineering as well as in the fields of materials science, mechanical engineering and structural engineering. Tensile strength is more important for brittle materials than ductile materials.

Explains Tensile Strength

The tensile strength of a material is the maximum amount of tensile stress that it can accept before failure (such as breaking or permanent deformation). Tensile strength specifies the point at which a material goes from elastic to plastic deformation. It is expressed as the minimum tensile stress (force per unit area) needed to split the material apart.

For example, if a metal rod one square inch in cross-section can withstand a pulling force of 1,000 pounds but breaks if more force is applied, the metal has a tensile strength of 1,000 pounds per square inch. The tensile strength for structural steel is 400 megapascals (MPa) and for carbon steel it is 841 MPa. Tensile strength values are different for different densities of steel.

There are three types of tensile strength:

Yield strength – The stress a material can withstand without permanent deformation
Ultimate strength – The maximum stress a material can withstand
Breaking strength – The stress coordinate on the stress-strain curve at the point of rupture
Tensile strength is a limit state of tensile stress that leads to tensile failure in one of two manners:

Ductile failure – Yield as the first stage of failure, some hardening in the second stage and breakage after a possible “neck” formation
Brittle failure – Suddenly breaking in two or more pieces at a low stress state
Tensile strength can be used in terms of either true stress or engineering stress.

Performing a tensile strength test for metals will determine how much an alloy will elongate before reaching its ultimate tensile strength and how much load a particular piece of metal can accommodate before it loses structural integrity. Therefore, understanding the tensile strength of materials is important for construction and personal safety.

Along with elastic modulus and corrosion resistance, tensile strength is an important parameter for materials that are used in structures and mechanical devices. It is specified for building materials such as alloys, composite materials, ceramics, plastics and wood.