tertiary creep

tertiary creep

[′tər·shē‚er·ē ′krēp]
(metallurgy)
Creep strain occurring at an accelerating rate leading to fracture.
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The transition between primary and tertiary creep seems to be shifted to higher strains for higher stresses.
The creep test in this study was performed under relatively high stress, allowing dislocations to slip easily past small obstacles such as [gamma]'-particles, which should have resulted in earlier softening and tertiary creep. The tensile stress of cast Haynes 282 alloy is 498 MPa at 750[degrees]C, and the melting temperature is 1,300-1,375[degrees]C; as such, the homologous temperature (T/Tm) would be 0.62-0.65.
6 (confining pressure of 10 MPa with acid solution injection, Figure 5(c)) undergoes a tertiary creep stage before ultimately losing its strength.
Lu, "Study of tertiary creep of rock salt," Journal of Engineering Mechanics, vol.
As is generally the case for creep behavior, the creep curve can be divided into three main regions; the primary creep region where the strain rate decreases with the number of load cycles applied; the secondary creep region where the strain rate is almost constant, otherwise known as the steady state strain rate; and the tertiary creep region where the strain rate increases rapidly up to failure.
Last, the tertiary creep occurs when a dramatic increase in creep rate is followed by an eventual rupture.
The variations of the hardening and weakening effects of geological material over time are shown in Figure 2 [18], from which it can be clearly noticed that the hardening effect increases gradually with a decreased rate during the transient stage and the steady-state stage and finally stays constant; however, the weakening effect increases linearly at first and evolves into an exponential growth trend during the tertiary creep stage.
This is followed by a region where the strain rate remains constant, [[??].sub.pl] (secondary creep), and eventually the terminal region is entered (tertiary creep), where the strain rate gradually increases until strain localization is initiated and failure occurs: creep rupture.
The "CoCrC=Ta" alloy knew first a very short primary creep, then a not really long secondary creep (constant rate of central point displacement), and finally a rapid tertiary creep leading to the contact of the central bottom face of the sample with the alumina support (about 1.4 mm of total displacement, after 25 hours of test).
Life prediction Is usually based on the secondary creep path until the onset of tertiary creep. Constitutive models such as visco-hyperelasticity and elasto-viscoplasticity can be used to make such prediction.

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