Non-linear modeling of stress relaxation curves for Grade 91 steel

다국어 초록 (Multilingual Abstract)

We focused on the modeling of the high-temperature Stress relaxation (SR) curves for Gr. 91 steel using two nonlinear models of a spring-dashpot and Peleg model to get a better fit to experimental relaxation data. A series of SR tests were performed under a constant strain of 0.6 % at 500, 550, 600 and 650 °C. The SR behavior of Gr. 91 steel was clarified based on the experimental data. In the modeling of the SR curves, each parameter value for the two models was optimized to give the best fit to the experiment SR data. The springdashpot model did not match the experimental data at 500 and 550 °C, although the model showed good agreement with the experimental data at 600 and 650 °C. However, the Peleg model was superior to the spring-dashpot model for all temperature conditions, and its parameter values followed temperature dependence well. Using the Peleg model, the SR curves for Gr. 91 steel could be suitably modeled at different temperature ranges. The confidence of the Peleg model was validated from elastic-creep finite element analysis. It is suggested that the Peleg model can be a useful tool to characterize the relaxation behavior of Gr. 91 steel.

참고문헌 (Reference)

1 P. Felthan, "Stress relaxation in copper and alpha-brasses at low temperatures" 89 : 210-214, 1961

2 ASTM, "Standard methods for stress relaxation tests for materials and structures, ASTM E328-13"

3 W. G. Kim, "Reliability assessment of creep rupture life for Gr. 91 steel" 51 : 1045-1051, 2013

4 J. D. Lubahn, "Plasticity and creep of metals" John Willy & Sons Inc 363-404, 1961

5 R. Myhan, "Non-linear stress relaxation model as a tool for evaluating the viscoelastic properties of meat products" 146 : 107-115, 2015

6 S. Holmstrom, "Long term stress relaxation modeling" 2014

7 김우곤, "Influence of data size on the reliability assessment of creep life of grade 91 steel" 대한기계학회 28 (28): 4493-4501, 2014

8 김우곤, "Influence of Hold Time and Stress Ratio on Cyclic Creep Properties Under Controlled Tension Loading Cycles of Grade 91 Steel" 한국원자력학회 49 (49): 581-591, 2017

9 W. G. Kim, "Cyclic creep behavior under tension-tension loading cycles with hold time of modified 9Cr-1Mo steel" 31 : 249-257, 2014

10 T. Shrestha, "Creep rupture behavior of Grade 91 steel" 565 : 382-391, 2013

11 B. K. Choudhary, "Creep behavior of modified 9Cr-1Mo steel" 412 : 82-89, 2011

12 M. Peleg, "Considerations of a general rheological model for the mechanical behavior of viscoelastic solid food materials" 2 : 243-255, 1976

13 H. Y. Lee, "Comparison of elevated temperature design codes of ASME subsection NH and RCC-MRx" 308 : 142-153, 2016

14 I. M. W. Ekaputra, "Characterization of the Q parameter for evaluating creep crack growth rate for type 316LN stainless steel" 대한기계학회 30 (30): 3151-3158, 2016

15 S. Spigarelli, "Analysis of the creep behavior of modified P91 (9Cr-1Mo-NbV) welds" 23 : 547-552, 2002