Various tests have been performed to determine the effect of hydrostatic pressure on
mechanical properties of materials. Test results at pressures up to 3.5 GPa indicate
that increasing the hydrostatic pressure substantially increases the strain at fracture,
both for ductile and for brittle materials. This beneficial effect of hydrostatic pressure
has been exploited in metalworking processes, particularly in hydrostatic extrusion
(Section 15 .4.2), and in compaction of metal powders