On the activation energy of high temperature creep in metals

1957 ◽  
Vol 2 (17) ◽  
pp. 584-588 ◽  
Author(s):  
Paul Feltham
1957 ◽  
Vol 24 (2) ◽  
pp. 207-213
Author(s):  
H. Laks ◽  
C. D. Wiseman ◽  
O. D. Sherby ◽  
J. E. Dorn

Abstract Experimental investigations on pure aluminum and its dilute solid-solution alloys revealed that the high-temperature creep rate ϵ̇ is related to the stress σ by ϵ̇ ∼ σn for low stresses and ϵ̇ ∼ eBσ for high stresses where n and B are constants independent of the creep strain and temperature. According to a preliminary dislocation-climb model for high-temperature creep, the activation energy for creep is that for self-diffusion, the effect of stress on the creep rate depends on the number of active Frank-Read sources, and the rate of climb depends on the structure as determined by the pattern of climbing dislocations. Many of the experimental observations on high-temperature creep can be accounted for by this model.


1961 ◽  
Vol 9 (11) ◽  
pp. 1036-1037 ◽  
Author(s):  
P. Feltham ◽  
J.D. Meakin

JOM ◽  
1956 ◽  
Vol 8 (10) ◽  
pp. 1385-1388 ◽  
Author(s):  
H. I-Lieh Huang ◽  
O. D. Sherby ◽  
J. E. Dorn

2020 ◽  
Vol 36 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen

ABSTRACTStructural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.


2014 ◽  
Vol 71 (5-6) ◽  
pp. 175-179
Author(s):  
V. G. Maksimov ◽  
D. V. Grashchenkov ◽  
V. A. Lomovskoi ◽  
V. G. Babashov ◽  
O. V. Basargin ◽  
...  

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