Visn. Nac. Akad. Nauk Ukr. 2017. (2): 70-75
https://doi.org/10.15407/visn2017.02.070

R.P. Prykhodko
Pisarenko Institute for Problems of Strength of  National Academy of Sciences of Ukraine, Kyiv

PREDICTION OF THE STRESS-RUPTURE STRENGTH AND MODELLING OF THE CREEP PROCESSES OF HIGH-TEMPERATURE CREEP-RESISTANT MATERIALS

A method to predict the stress-rupture strength of materials using the master-curve concept is presented. Simple formulas relating the theoretical lifetime and the corresponding stress determined from the master curve are proposed. To improve master-function calculations, an assumption is made on linear dependence on the cotangent of the angle between the ordinate axis and a segment of the stress-rupture curve plotted on log–log scale. The parameters of the linear function are assumed invariant to the test temperature. The method is capable of extrapolating, with accuracy sufficient for practical purposes, the lifetime to values that are more than two orders of magnitude greater than the available experimental data. The efficiency of the method is illustrated by calculating the lifetime of steels SUS 316-HP (18Cr–12Ni–Mo), and JIS SCMV 4NT (2.25Cr–1Mo) for quite wide ranges of stress and temperature. It is shown that the method has advantages over the master-curve approach and popular parameters such as Larson–Miller, Orr–Sherby–Dorn, Manson–Succop, Conrad’s, Korchynsky–Clauss, and Trunin’s.

Keywords: creep, parametric methods, specification of constitutive equations.

 Language of article: ukrainian

REFERENCES

1. Trunin I.I. A mechanical equation of the condition of metal materials and prediction of high-temperature strength characteristics. Strength Mater. 1976. 6(9): 1013. https://doi.org/10.1007/BF01529843
2. Larson F.R., Miller J. Time temperature relationship for rupture and creep stresses. Trans. ASME. 1952. 74(5): 765.
3. Orr R.L., Sherby O.D., Dorn J.E. Correlation of rupture data for metals at elevated temperatures. Trans. ASM. 1954. 46: 113.
4. Manson S.S., Haferd A.M. A linear time-temperature relation for extrapolation of creep and stress rupture data. NACA Technical Note 2890. 1953.
5. Krivenyuk V.V. Prediction of high-temperature creep and rupture strength. Series: Materials and constructions strength. Vol. 5. (Kyiv, 2012). [in Russian].
6. Kucher N.K., Prikhod’ko R.P., Borovik O.V. Prediction of creep and long-term strength of materials under anisothermic deformation. Strength Mater. 2013. 45(1): 93.
https://doi.org/10.1007/s11223-013-9436-3
7. Romashov R.V. Materials long-term strength characterization on the results of limited duration tests. Advances in current natural sciences. 2006. (11): 69. [in Russian].