PSI - Issue 18

3

Tretyakov M.P. et al. / Procedia Structural Integrity 18 (2019) 816–822 Author name / Structural Integrity Procedia 00 (2019) 000–000

818

Table 1. Mechanical composition of steel X15CrNi12-2. C Cr Si Nb

Ni

W

Mo

V

0,13 %

12,50 %

0,05 %

0,20 %

2,05 %

0,70 %

1,50 %

0,20 %

The tests were carried out on the Instron 5982 universal electromechanical testing system (± 100 kN). A general view of the equipment layout when conducting high temperature tests is shown in Fig. 1 (a). The measurement error of the load sensors of the testing machine is 0.5% of the measured value in the load range from 0.2 kN to 1 kN and 0.4% in the load range from 1 kN to 100 kN. In Fig. 1, the following components are marked with numbers: 1 - frame and traverse of the testing machine, 2 - cooled grippers for working with high-temperature furnaces, 3 - high temperature furnace for heating samples, 4 - cooling system of grips and extensometer by circulating and cooling water , 5 - temperature control device on the sample surface using thermocouples, 6 – high temperature furnace control controller. At the initial stage of testing, deformations were measured using the Epsilon high-temperature extensometer of the induction type Epsilon 3648-010M (Fig. 1, a). The samples were heated in a three-zone Instron CP103202 furnace with a maximum operating temperature of 1100 ° C (Fig. 1, c), the sample and the thrusts of the cooled grippers are in the furnace.

b

c

a

Fig. 1. Set of test system (a); (b) high temperature extensometer; (c) chamber for high temperature tests.

The peculiarity of the design of the furnace and gripping devices due to the geometry of the samples for testing. The sketch of the sample was developed taking into account the recommendations of the standards GOST 1497-84 “Metals. Method of tensile test” and GOST 26007-83 “Calculations and tests of strength. Methods of mechanical testing of metals. Test methods for stress relaxation”. Fig. 2 shows a sketch (a) and the appearance (b) of a solid cylindrical specimen. The fastening of the sample is carried out by means of threaded connections, which allows testing with the transition through a zero value on the load. Since the work provides for the construction of complete deformation diagrams with areas of softening (reducing the load applied to the sample, while increasing the elongation), the tests were carried out under kinematic loading conditions with movement control using the built-in sensor of the testing machine. The temperature regimes and test