Creep and Creep Curves

At any temperature theoretically speaking a material will progressively deform beneath a constant load even whether the stress is below yield. Such deformation however is negligibly small.

At high temperature, although the progressively deformation of a material beneath a constant stress is termed like creep and can become rather appreciable depending on the combination of temperature and stress. The material deformation in laboratory is frequently measured like strain suffered via tension specimen. The temperature at such creep as to be appreciable is half of the melting point temperature upon absolute scale and is termed as homologous temperature.

The creep experiments could be performed in easy machines that employ dead lever and weights for loading the tension test piece. The specimen is surrounded via a furnace that temperature can be recorded and prohibited accurately with elongation of specimen. That arrangement is represented in following figure (a) with no furnace. While not exactly true the definite complicated arrangement for deformation measurement of creep test piece may be like one represented in following figure (b).

                    Figure: (a) Schematic of Creep Testing Equipment; and (b) An Arrangement for Measuring