PSI - Issue 18

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000

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Procedia Structural Integrity 18 (2019) 816–822

25th International Conference on Fracture and Structural Integrity Experimental study of the rheological behavior of steels at the postcritical deformation stage at high temperature Tretyakov M.P. a *, Wildemann V.E. a a Center of Experimental Mechanics, Perm National Research Polytechnic University, 29 Komsomolskiy Ave., Perm, 614990, Russia Abstract A methodological issue for carrying out the rheological tests of structural steels at the postcritical stage of deformation at high temperatures under conditions of tensile tests with the possibility of registering changes in the geometry of the strain gauge of the samples during the testing has been considered. The methodology for rheological tests at high temperatures is based on the use of the electromechanical test system, which include the cooled grips, high-temperature furnace for heating samples, cooling system for grips and extensometer, control device for measure of temperature on the sample surface using thermocouples. In accordance with the design of the used furnaces and gripping devices, sketches of samples were developed for tensile tests and tensile-torsion tests. The temperature regimes and test speeds were determined, and the sequence of loading and holding the samples was chosen in accordance with the objectives of the study. Experimental data on the effect of test temperature on creep and relaxation of structural steels, previously subjected to postcritical deformation, were obtained. Experimental diagrams of deformation of X15CrNi12-2 steel samples at a temperature of 400 °C, 500 °C and 600 °C with exposures with fixed deformation at various stages of elastoplastic and postcritical deformation were constructed. Experimental data obtained during the project implementation show that during the deformation of steel at the postcritical stage of deformation at high temperatures, rheological processes actively occur. The relaxation processes in samples at the postcritical stage of deformation substantially depend on the test temperature and the degree of elongation achieved by the time of exposure. An increase in temperature leads to a more intensive decrease in the relative load at exposures, and an increase in the degree of postcritical deformation leads to an increase in the intensity of relaxation processes, and this effect is most pronounced with increasing temperature. The revealed experimental dependences confirm the need to take into account the rheological component of the mechanical behavior of steels when studying postcritical behavior at high temperatures. 25th International Conference on Fracture and Structural Integrity Experimental study of the rheological behavior of steels at the postcritical deformation stage at high temperature Tretyakov M.P. a *, Wildemann V.E. a a Center of Experimental Mechanics, Perm National Research Polytechnic University, 29 Komsomolskiy Ave., Perm, 614990, Russia Abstract A thodological issue for carrying out the rheological tests of structural steels t the postcritical stage of deformation at high te eratures und r condition of tensile tests with the possibi ity o egistering changes in the geometry of the strain gaug of the sampl s during the tes ing ha been considered. The metho ology for r eologic l tests at high temperatures is based n the u e of the electromechanical t st system, which includ the co led grips, high-temperatur f rn for heating samples, cooling system for grips and extensomet r, co trol device for measure of temperature on th sample surface using thermocouples. In accordance wi h the design of th used furn ces and gripping d vic s, sk tches of samples w re developed for tensile est and tensile-torsio tests. The temperature regimes and tes speeds were d termined, nd the s quen e loading and holding th samples was chosen in a cordanc with the objectives of the study. Experimental data on th effect of test t mp rature on creep an relax structural steels, previously subject d o p stcritical deform tion, were obtained. Exper mental iag ams of deformation of X15CrNi12-2 steel samples at a t mper ture of 400 °C, 500 °C and 600 °C with exposur s with fixed deformation at various stages of elastoplastic and postcritical deforma ion were constructed. Experi ental d a obtained during the pr ject im lem ntation show that during the def rmation of steel at the postcritical stage of deformation at high temperatur s, rhe logical process s actively occur. Th relaxation process s in sampl s at the postcritical stage of deformation substanti lly depend on the test temperature and the degree of elongation achieved by th time of exposure. An n rease in temperature le ds to a more inte sive decrease in the relative load at exposur s, and an increase in the degree of postcritical deformation leads to an increase in the i tensity of relaxation processes, and this effec is most pronounced with increasing temper tur . The reveal d exp rimental de endences confirm the need to take into account the rheological component of the mechanical behavior of steels when studying postcritical behavior at high temperatures.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Autho s. Publ shed by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. * Corresponding author. Tel.: +7-342-239-1111; fax: +7-342-239-1224. E-mail address: cem_tretyakov@mail.ru * Corresponding author. Tel.: +7-342-239-1111; fax: +7-342-239-1224. E-mail address: cem_tretyakov@mail.ru

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.231