Elongation at Break

Elongation at Break or Elongation is one measure of ductility. The conventional means by which we obtain Elongation is by pulling a specimen in tension until fracture. Elongation is defined as the increase in the gauge length, Lo, of a test piece subjected to tensile forces divided by the original gauge length. Elongation is expressed as a percentage of the original gauge length and is given by:

Elongation (%) = ΔL/Lo x 100

Where:

Lo is the original gauge length

ΔL is the change in length of the original gauge length measured after the specimen fractures and the specimen is fitted together

A punch is often used to apply the gauge marks to each specimen. The change in gauge length, ΔL, is determined by carefully fitting the ends of the fractured specimen together and measuring the distance between the gauge marks. In reporting Elongation, both the original gauge length and percentage increase are to be reported. If any portion of the fracture occurs on or outside a gauge mark, Elongation may not be representative of the material