The thermal treatment of an alloy that increases the hardness and strength by precipitation of constituents from the super-saturated solid solution at above room temperature.
A hydraulic or pneumatic test for tubes to prove that they material can withstand a specified pressure for a specified time without leakage or rupture.
Proof Stress (Rp)
The stress or applied load which produces a permanent elongation equal to a specific percentage of the original gauge length. In alloys that do not exhibit a yield point it is used as an equivalent to the elastic limit.
If a proof stress is specified, the non-proportional elongation must be stated. The most common values used in specifications is 0.2% or 1.0% and the RP symbol used for the stress will be supplemented by an index giving this prescribed percentage of the original gauge length, e.g. RP0.2 = 0.2% Proof Stress.