The Small Punch Test (SPT)
In the small punch test, a disk-shaped specimen (D8 x 0.5 mm) is clamped between a die (bore diameter D=4 mm) and a downholder and deformed by the punch with a spherical head (radius r=1.25 mm). Characteristic parameters of the force-displacement curves are used to estimate mechanical properties (yield stress, ultimate tensile stress). Force-displacement curves at different temperatures allow the estimation of the ductile to brittle transition temperature (DBTT). For irradiated materials the SPT-device is put into a hot cell.
|Scheme of the small punch test
|Force-displacement curves at different temperatures (Steel T91)