PSI - Issue 65

Kuskov K.V. et al. / Procedia Structural Integrity 65 (2024) 133–138 Kuskov K.V./ Structural Integrity Procedia 00 (2024) 000–000

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Fig. 3. The dependency graph of the damages’ sum on the fatigue strength for sample 1 of series 2 for the 30KhGSA steel.

The obtained values of the fatigue strength are presented in Table 7. They are determined by the Locati method for all sorts of steels.

Table 7. Results of the fatigue strength determination by the Locati method. The fatigue strength σ -1 , МPа 35 30KhGSA 45

40Kh

Sample 1 Series 1 Sample 2 Series 1 Sample 3 Series 1 Sample 1 Series 2 Sample 2 Series 2 Sample 3 Series 2

253

491

251

332

250

500

247

329

257 253 268

494 495 495

244 247 261

323 328 334

Measurement Average

261

500

255

341

272 267

490 495

246 254

330 335

Measurement Average

The fatigue strength values for all sorts of steels turn out to be slightly higher than in the literature data (see Agamirov L. V. and Vestyak V. A. (2020); Jihed Zgal et al. (2016); Trofimov O.F. (2012); Fabian Weber at al. (2023)). This is due to the fact that non-standard samples with a lower voltage temperature coefficient value are used. It is previously assumed in the study (see Kuskov K.V., Syzrantseva K.V. (2023)).

4. Conclusion

The results show that the roughness direction has an effect on the fatigue strength. The increase in the fatigue strength is from 2 to 5% in the roughness direction located along the tensile and compressive stresses action for the steels 35, 45, 40Kh with the parameter R a = 0.11 μm. The difference in the fatigue characteristics for 30KhGSA steel samples may be due to the fact that the surface layer is strengthened by the diffusion of alloying elements during the processing of preliminary load stages below 0.5*σ t . (see Terentyev V. F. (2006)). This effect probably reduces the influence of the roughness direction.