Structuroscopy of Coils after High-Temperature Mechanical Treatment on the Basis of Measurements of Rayleigh Waves Velocity

For the manufacture of spring springs of rolling stock (wagons, locomotives, cars), bars made of spring steels are used. With high-temperature machining, when winding springs and quenching them, there is a difference in the cooling rates of the inner and outer sides of the spring coils, which leads to a difference in the structural state and affects the durability of the springs. The aim of the work is to study the effect of structural changes in the outer and inner surfaces of spring steel coils after winding and high–temperature machining operations on the measured characteristics of Rayleigh acoustic waves.

The propagation velocities of Rayleigh waves in spring-spring steel 60C2A after winding and hightemperature machining operations are investigated. The shadow method and the autocirculation method with piezoelectric converters CTS-19 with a frequency of 5 MHz with a special block design were used for research. The converters provide input and reception of the Rayleigh wave along the inner and outer forming surface of the spring. It is shown that the method of comparing the results of measuring the velocity of Rayleigh waves on a fi base by the coil generator on the inner and outer surfaces of the spring is sensitive to disturbances in the structure of the material and the appearance of defects. An unambiguous relationship of the structural states on the outer and inner sides of the spring with the velocity of the Rayleigh wave is found.

As a result of the measurements, a conclusion was made about the significant sensitivity of Rayleigh waves to the structural state of the steel under study. An increase in the wave velocity was detected on the inner surface of the coil in the contact zone with the mandrel relative to the outer side of the coil, signaling incomplete hardening of steel in this zone during high-temperature machining. The relative speed difference in different spring samples is approximately up to 1 % (≈ 30 m/s), which is a significant value for assessing the quality of high-temperature machining.

1. Orlova A.M., Rudakova E.A., Shevchenko D.V., Gusev A.V., Shalpegin G.S. [Approaches to assessing the stress-strain state of freight car spring suspension coils]. Izvestiya peterburgskogo universiteta putej soobshcheniya, 2020, vol. 17, no. 2, pp. 221–232 (in Russian). DOI: 10.20295/1815-588X-2020-2-221-232

2. Sunʼ H., Danilov V.L. [Analysis of residual stres-ses in helical cylindrical springs at high temperature]. Nauka i obrazovanie: nauchnoe izdanie MGTU im. N.E. Baumana [Science and Education of Bauman MSTU], 2015, no. 6, pp. 384–396 (in Russian). DOI: 10.7463/0615.0778617

3. Del Llano-Vizcaya L., Rubio-Gonzales C., Mesmacqueb G., Banderas-Hernándeza A. Stress relief effect on fatigue and relaxation of compression springs. Materials and Design, 2007, vol. 28, no. 4, pp. 1130–1134. DOI: 10.1016/j.matdes.2006.01.033

4. Ulrike Karr, Yusuke Sandaiji, Ryota Tanegashima, Shogo Murakami, Bernd Schönbauer, Michael Fitzka, Herwig Mayer. Inclusion initiated fracture in spring steel under axial and torsion very high cycle fatigue loading at different load ratios. International Journal of Fatigue, 2020, vol. 134, p. 105525. DOI: 10.1016/j.ijfatigue.2020.105525

5. Lavrinenko YU.A. [Study of strain-stress state during springs coiling by combination loading]. Zagotovitel'nye proizvodstva v mashinostroenii, 2017, vol. 15, no. 9, pp. 399–404 (in Russian).

6. Okolovich G.A., Kurakov D.V., Sharikova T.G., Chekalina S.A. [Heat treatment of springs of railway transport]. Polzunovskij al'manah, 2015, no. 2, pp. 141– 145 (in Russian).

7. Titov A.V. [The effect of heat treatment on the microstructure of springs for critical applications SA of steel and titanium alloy VT16]. Metalloobrabotka, 2015, no. 5(89), pp. 43–49 (in Russian).

8. Orlova A.M., Rudakova E.A., Shevchenko D.V., Gusev A.V., Popovich C.I., Savushkin R.A. [Analysis of design procedures for horizontal spring stiffness of bogie suspension of freight cars]. Izvestiya peterburgskogo universiteta putej soobshcheniya, 2019, vol. 16, no. 2, pp. 191–201 (in Russian). DOI: 10.20295/1815-588X-2019-2-191-201

9. Grigor'ev V.M., Makienko V.M., Sokolov P.V. [Analysis of the springs destruction of the passenger carriage]. Transport Aziatsko-Tihookeanskogo regiona, 2015, no. 1(2–3), pp. 94–97 (in Russian).

10. Markov A.M., Gabets A.V., Gabets D.A., Gavrikov D.V. [Coil spring group for freight-car truck]. Aktual'nye problemy v mashinostroenii [Actual problems in machine building], 2016, no. 3, pp. 194–198 (in Russian).

11. Zlobin D.V., Murav'eva O.V. [Development features of electromagnetic acoustic defectoscopy equipment for bar iron using rod waves]. Vestnik IzhGTU imeni M.T. Kalashnikova, 2012, no. 4, pp. 99–104 (in Russian).

12. Murav'eva O.V., Sokov M.YU. [Influence of the defect depth on the parameters of electromagnetic-acoustic multiple-shadow method of the rod testing]. Vestnik IzhGTU imeni M.T. Kalashnikova, 2016, vol. 19, no. 3, pp. 46–50 (in Russian).

13. Petrov K.V., Sokov M.YU., Murav'eva O.V. [The effect of electromagnetic acoustic transducer design features on results of cylinder object testing]. Vestnik IzhGTU imeni M.T. Kalashnikova, 2018, vol. 21, no. 2, pp. 135–146 (in Russian). DOI: 10.22213/2413-1172-2018-2-135-146

14. Baev A.R., Majorov A.L., Tishchenko M.A. Ultrasonic methods of analysis of the metal articles surface hardening. Foundry production and metallurgy, 2010, no. 4, pp. 267–271 (in Russian).

15. Volkova L.V., Platunov A.V. [Rail base point inspection using the mirror through transmission testing technique on multiple reflections]. Vestnik IzhGTU imeni M.T. Kalashnikova, 2019, vol. 22, no. 4, pp. 38–45 (in Russian). DOI: 10.22213/2413-1172-2019-4-38-45

16. Muravʼev V.V., Zuev L.B., Komarov K.L. [Sound Speed and Structure of Steels and Alloys]. Novosibirsk, Nauka Publ., 1996, 184 p.