| Title |
Long-term Creep Strain-Time Curve Modeling of Alloy 617 for a VHTR Intermediate Heat Exchanger |
| Authors |
김우곤(Woo Gon Kim); 윤송남(Song Nan Yin); 김용완(Yong Wan Kim) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
creep; creep curve; nonlinear Least square fitting; NLSF; kachanov-rabotnov (K-R) model; Alloy 617 |
| Abstract |
The Kachanov-Rabotnov (K-R) creep model was proposed to accurately model the long-term creep curves above 10(5) hours of Alloy 617. To this end, a series of creep data was obtained from creep tests conducted under different stress levels at 950℃. Using these data, the creep constants used in the K-R model and the modified K-R model were determined by a nonlinear least square fitting (NLSF) method, respectively. The K-R model yielded poor correspondence with the experimental curves, but the modified K-R model provided good agreement with the curves. Log-log plots of ε*-stress and ε*-time to rupture showed good linear relationships. Constants in the modified K-R model were obtained as λ=2.78, and κ=1.24, and they showed behavior close to stress independency. Using these constants, long-term creep curves above 10(5) hours obtained from short-term creep data can be modeled by implementing the modified K-R model. |