An Analysis of Creep Deformation and Rupture by the $\beta$-Envelope Method
An Analysis of Creep Deformation and Rupture by the $\beta$-Envelope Method
For several decades creep deformation and fracture have been analysed by parameters such as steady state creep rate $\epsilon_min$ and rupture time t$_{r}$. However, the relations based an these parameters contain a number of constants which arethemselves dependent an the variables. For example, in...
Saved in:
Personal Name(s): | Radhakrishnan, V. M. |
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Ennis, P. J. / Schuster, H. | |
Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
1991
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Physical Description: |
38 p., Anh. |
Document Type: |
Report Book |
Research Program: |
ohne Topic |
Series Title: |
Berichte des Forschungszentrums Jülich
2535 |
Link: |
OpenAccess |
Publikationsportal JuSER |
For several decades creep deformation and fracture have been analysed by parameters such as steady state creep rate $\epsilon_min$ and rupture time t$_{r}$. However, the relations based an these parameters contain a number of constants which arethemselves dependent an the variables. For example, in Norton's equation for the steady state creep rate $\epsilon_min$=A.$\sigma^{n}$ where A and n are constants, $\sigma$ the applied stress, the exponent n may depend on the stress itself. Further, structural changes may take place during creep deformation which are not properly reflected in the relation. Recently early approaches based on creep equations have been revived to describe the creep deformation and fracture. In this report creep equations of the type $\epsilon_{1}$ = $\beta_{1}$t$^{1/3}$ and $\epsilon_{2}$ = $\beta_{2}$t and $\epsilon_{3}$ = $\beta_{3}$t$^{3}$ where $\epsilon_{1}$, $\epsilon_{2}$, $\epsilon_{3}$ are the ereep strains in the primary, secondary and tertiary stages, $\beta_{i}$ the respective coefficients and t the time, are used to envelope the creep strain data on the log-log plot of creep strain versus time. Based on this approach the creep behaviour of the following engineering materials has been analysed:X10 NiCrAlTi 32 20 (Allog 800 H) / 13 CrMo 4 4 (1 Cr- 0.5 Mo) steel in both new and service exposed conditions 14 CrMoV 6 3 (0.5 Cr- 0.5 Mo - 0.25 V) steel a Ni-base superalloy. The analysis leads to an important modification of the Dobès-Milicka rule, namely, that the minimum creep rate $\epsilon_{min}$ and the rupture time t$_{r}$ are related not only to the creep rupture strain $\epsilon_{r}$ but also to the creep strain at the end of the second stage $\epsilon_{23}$, given in the form $\epsilon_{min}$t$_{r}$ = $\sqrt[3]{{\epsilon}^{2}_{23} \cdot \epsilon_{r}}$ |