PSI - Issue 47

Aleksandr Inozemtsev et al. / Procedia Structural Integrity 47 (2023) 705–710 Author name / Structural Integrity Procedia 00 (2019) 000–000

709

5

Fig.3. (a) Characteristic one-dimensional profile; (b) plot Log 2 K(r) vs. Log 2 (r) .

Table 3 shows the values of the Hurst exponent and the corresponding spatial scales for specimens after normal multi-cycle fatigue and dwell fatigue tests. Table 3. The values of the Hurst exponent H and scales L pz and l sc at various levels of fatigue longevity. Specimen number The direction of cutting in relation to the direction of rolling Dwell time ,s Maximal. stress, MPa  , cycles  l sc , mkm L pz , mkm H

0.58±0.01 0.50±0.02 0.54±0.01 0.58±0.02 0.56±0.1 0.55±0.01 0.51±0.02 0.45±0.01 0.54±0.03 0.58±0.02

25.3±0.9 43.1±9.8 50.9±4.4 36.6±5.3 96.6±1.6 26.2±0.2 49.7±4.8 23.3±0.9 28.6±4.2 26.6±7.9

0.3±0.1 0.8±0.5 0.3±0.1 1.5±1.2 0.5±0.2 0.3±0.1 0.7±0.2 0.3±0.1 0.7±0.4 0.3±0.1

281 4481 787 4641 1152 4818

910 850 885 865 875 875 885 875 775 800

120 120 120 120 600 120 120 300

longitudinal longitudinal longitudinal longitudinal longitudinal transverse transverse transverse transverse transverse

17-8883-pv 17-8884-pv 17-8886-pv 17-8887-pv 17-8890-pv 17-8902- pp 17-8903-pp 17-8904- pp 17-8919-pp 17-8920-pp

967 288

35740 27823

0 0

The comparative analysis of scale-invariant characteristics of specimens made of titanium alloy Ti-6Al-4V after multicyclic fatigue and dwell fatigue tests has shown that there is a significant increase in the range of spatial scales up to 0,5-96,6 microns for specimens with dwell period in contrast to specimens without dwell period (H~0,5 in the range of spatial scales of 0,7-28,6 microns). 3. Conclusion The role of microtextured region and morphology in evaluating the dwell fatigue effect in titanium alloy Ti-6Al 4V is studied. Thus far, the relationship between particular microstructures and dwell fatigue damage has remained mechanistically uncertain, so that the main objective of this research is to establishes a link between microtextured region and dwell fatigue damage, and to gain insight into the mechanisms of preferential sub-surface facets nucleation under conditions of dwell fatigue loading. The New View 5010 high-resolution interferometer profiler was used as an effective tool for quantitative analysis, which makes it possible to establish the correlations between mechanical properties and scale-invariant (scaling) characteristics of defect-induced structures formed during fatigue loading. The obtained optical images of the macro-