Mechanical Properties

Tensile Strength
The maximum load applied in breaking a tensile test piece divided by the original cross-sectional area of the test piece. (The maximum stress value obtained on a stress-strain curve).

Proof Stress
The stress that will cause a specific small, permanent extension of a tensile test piece. (The stress on the stress-strain curve corresponding to a definite amount of permanent set or strain )

Creep Strength
Continuing changes in dimensions of a stressed material over time, a constant tensile load is applied under a specified temperature (This is not Creep Rupture - which is when the material fails).