CHANGES IN FATIGUE RESISTANCE OF STRUCTURAL STEELS AT DIFFERENT LOADING SPECTRA

Fatigue strength of widely used engineering structural steels was  studied at various frequencies of loading according to the scheme of  cantilever bending of the rotating cylindrical samples. Fatigue resistance index is tangent of angle of inclination of fatigue curve to axis  of longevity. It is established that 40 and 45 steels belong to the group  of materials in which decrease in frequency of loading leads to cyclic  softening and decrease in fatigue resistance, which is numerically expressed by increasing slope of fatigue curve. Tests of the samples made  of 40X steel had shown that increase in frequency of loading cycles  leads to a noticeable decrease in slope of fatigue curve parameter, i.e.  to an increase in fatigue resistance. Decrease in fatigue resistance parameter is associated with an increase in hardening of material of the  samples (parts) surface layers which reduces fatigue damage to the  surface itself. Dependence of the fatigue curve slope tangent on surface damage at changing loading cycles frequency is shown and it is  stated that, regardless of frequency, damage of material surface layers  increases along the slope of fatigue curve. For each of these groups  mathematical relations are defined. The correlation coefficient providing degree of convergence of experimental results with the constructed fatigue curve was adopted as a criterion of cyclic behavior stability  of steels. It is revealed that increase in behavior stability of 40X steel  is observed with increase in cyclic deformation rate. Tests of 45  steel  have shown that decrease in cyclic strength with increase in loading  frequency does not affect fatigue stability of material. Increased dispersion of experimental results was observed in 40 steel at low loading  frequency, despite the high values of cyclic strength at given loading  frequency. On the basis of conducted experiments, dynamics of behavior of real machine parts and structures subjected to cyclic loads  operating was determined in the studied loading spectrum.

frequency of loading cycles,  fatigue resistance,  strength,  durability,  engineering steel,  hardening,  surface damage

1. Terent’ev V.F., Korableva S.A. Ustalost’ metallov [Metal fatigue].  Moscow: Nauka, 2015, 479 p. (In Russ.).

2. Suresh S. Fatigue of metals. Cambridge University Press, 2006, 701  p. 

3. Gromov V.E., Ivanov Yu.F., Vorobiev S.V., Konovalov S.V. Fatigue of steels modified by high intensity electron beams. Cambridge,  2015, 272 p.

4. Honeycombe R.W.K. The Plastic Deformation of Metals. London:  Edward Arnold Ltd., 1984, 483 p.

5. Kazymyrovych V. Very high cycle fatigue of engineering materials – A literature review. Karlstad University Studies, 2009, 22 p.

6. Panin V.E. Fizicheskaya mezomekhanika materialov. Tom 1 [Physical mesomechanics of materials. Vol. 1]. Psakh’e S.G. ed. Tomsk:  TGU, 2015, 462 p. (In Russ.).

7. Vladimirov V.I. Fizicheskaya priroda razrusheniya metallov [Physical nature of metals destruction]. Moscow: Metallurgiya, 1984,  280  p. (In Russ.).

8. Shanyavskii A.A. Bezopasnoe ustalostnoe razrushenie elementov aviakonstruktsii. Sinergetika v inzhenernykh prilozheniyakh [Safe  fatigue failure of aircraft components. Synergy in engineering applications]. Ufa: Monografiya, 2003, 803 p. (In Russ.).

9. McEvily A.J. Metal Failures: Mechanisms, Analysis, Prevention.  New York: Wiley, 2002, 324 p. (Russ.ed.: McEvily A.J. Analiz avariinykh razrushenii. Moscow: Tekhnosfera, 2010, 416 p.).

10. Schijve J. Fatigue of structures and materials in the 20th century and  the state of the art. International Journal of Fatigue. 2003, vol.  25,  pp. 679–702.

11. Shkol’nik L.M. Metodika ustalostnykh ispytanii. Spravochnik [Fatigue testing technique. Reference book]. Moscow: Metallurgiya,  1978, 304 p. (In Russ.).

12. Troshchenko V.T., Sosnovskii L.A. Soprotivlenie ustalosti metallov i splavov [Fatigue resistance of metals and alloys]. Kiev: Naukova  dumka, 1987, 1303 p. (In Russ.).

13. Ivanova V.S., Shanyavskii A.A. Kolichestvennaya fraktografiya. Ustalostnoe razrushenie [Quantitative fractography. Fatigue fracture]. Moscow: Metallurgiya, 1988, 399 p. (In Russ.).

14. Pachurin G.V., Gushchin A.N., Pachurin K.G., Pimenov G.V. Tekhnologiya kompleksnogo issledovaniya razrusheniya deformirovannykh metallov i splavov v raznykh usloviyakh nagruzheniya. Ucheb. posobie [Technology of comprehensive study of destruction of deformed metals and alloys under different loading conditions. Manual]. Nigny Novgorod: izd NGU, 2005, 141 p. (In Russ.).

15. Haw-Ming Huang, Wei-Jen Chang, Nai-Chia Teng, Hung-Lung  Lin,  and  Sung-Chih  Hsieh.  Structural  analysis  of  cyclic-loaded  nickel-titanium rotary instruments by using resonance frequency as  a parameter. JOE. 2011, vol. 37, no. 7, pp. 993–996.

16. Kotsan’da S. Ustalostnoe rastreskivanie metallov [Fatigue cracking  of metals]. Trans. from Polish. Yarema S.Ya. ed. Moscow: Metallurgiya, 1990, 432 p. (In Russ.).

17. Weiss T., ASTM Bulletin, 1949, February, p. 188; p. 31.

18. Proceedings of the Int. Conf. VHCF-5, June 28-30, 2011, Berlin. Berger C., Christ H.-J. eds. Berlin, Germany: DVM, 2011, 980 p.

19. Sulima A.M., Evstigneev M.I. Kachestvo poverkhnostnogo sloya i ustalostnaya prochnost’ detalei iz zharoprochnykh i titanovykh splavov [Surface layer quality and fatigue strength of parts made  of heat-resistant and titanium alloys]. Moscow: Mashinostroenie,  1974, 255 p. (In Russ.).

20. Yakovleva T.Yu., Matokhnyuk L.E. Prediction of fatigue characteristics of metals at different loading frequencies. Strength of Materials. 2004, vol. 36, nо. 4, pp. 442–448.

21. Yasnii P.V., Marushchak P.O., Panin S.V., Lyubutin P.S., Ba ran  D.Ya.,  Ovechkin B.B. The stages of material deformation and growth kinetics of fatigue crack in 25Kh1M1F steel at low loading frequencies. Fizicheskaya mezomekhanika. 2012, vol. 15, no. 2, pp. 97–107.  (In Russ.).

22. Konovalov S., Aksenova K., Gromov V., Ivanov Yu., Semina O. The  influence of electron beam treatment on alloy structure destroyed at  high-cycle fatigue. Key Engineering Materials. 2016, vol. 675-676,  pp. 655–659.

23. Mughrabi H., Christ H. - J. Cyclic deformation and fatigue of selected ferritic and austenitic steels; specific aspects. ISIJ International.  1997, vol. 37, no. 12, pp. 1154–1169.

24. Musuva J. K. Radon J. C. The effect of stress ratio and frequency  on fatigue crack growth. Fatigue of Eng. Materials and Structures.  1979, vol. 1, pp. 457–470.

25. Marines I., Bin X., Bathias C. An understanding of very high cycle  fatigue of metals. International Journal of Fatigue. 2003, vol. 25,  no. 9-11. pp. 1101–1107.

26. Mylnikov V.V., Shetulov D.I., Chernyshov E.A. Variation in factors of fatigue resistance for some pure metals as a function of the frequency of loading cycles. Russ. J. Non-Ferr. Met. 2010, vol. 51,  no. 3, pp. 237–242.

27. Shetulov D.I. Relation of resistance to cyclic loading with metals  surface damage. Izv. Akademii Nauk. Metally. 1991, no. 5, pp. 160.  (In Russ.).

28. Myl’nikov V.V., Shetulov D.I., Chernyshov E.A. Investigation  into the surface damage of pure metals allowing for the cyclic  loading frequency. Russ. J. Non-Ferr. Met. 2013, vol. 54, no. 3,  pp. 229–233.

29. Myl’nikov V.V., Shetulov D.I., Chernyshev E.A. On evaluation of  durability criteria in carbon steels. Metals Technology. 2010, no. 2,  pp. 19–22.

30. Myl’nikov V.V., Chernyshov E.A., Shetulov D.I. Influence of cyclic  loading frequency on fatigue resistance of high-strength structural  materials. Zagotovitel’nye proizvodstva v mashinostroenii. 2009,  no. 2, pp. 33–36. (In Russ.).

31. Myl’nikov V.V. On the effect of load application frequency on fatigue resistance of materials. Mezhdunarodnyi zhurnal prikladnykh i fundamental’nykh issledovanii. 2016, no. 6-2, pp. 202–205. (In  Russ.).