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Glossary
Creep Recovery.
Rate of decrease in deformation that occurs when load is
removed after prolonged application in a creep test. Con-
stant temperature is maintained to eliminate effects of
thermal expansion, and measurements are taken from
time load is zero to eliminate elastic effects.
Creep Rupture Strength.
Stress required to cause fracture in a creep test within a
specified time. An alternate term is stress rupture strength.
Creep Strength.
Maximum stress required to cause a specified amount of
creep in a specified time. Also used to describe maxi-
mum stress that can be generated in a material at con-
stant temperature under which creep rate decreases with
time. An alternate term is creep limit.
Creep Test.
Method for determining creep or stress relaxation behav-
ior. To determine creep properties, material is subjected
to prolonged constant tension or compression loading at
constant temperature. Deformation is recorded at speci-
fied time intervals and a creep vs time diagram is plot-
ted. Slope of the curve at any point is creep rate. If
failure occurs, it terminates the test and time for rupture
is recorded. If the specimen does not fracture within test
period, creep recovery may be measured. To determine
stress relaxation of material, specimen is deformed a
given amount and decrease in stress over prolonged pe-
riod of exposure at constant temperature is recorded.
Standard creep testing procedures are detailed in ASTM
B-7
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