OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 4 2022 algorithm and 3D visualization (Fig. 17) of seven hundred and twenty two-dimensional projections rotated relative to each other at an angle of 0.5°. Images of cracks that appeared during external loading were successfully reconstructed. There is a good agreement between the calculated data and the actual data. The results obtained in the work allowed the authors based on the example of welded joints to conclude that the computed laminography method is highly effective for studying the processes of fatigue failure of materials. The information obtained by this method is important from the view of the development of materials characterized by a high level of fatigue properties. Investigation of contact fatigue cracks One of the applications of the method of synchrotron computed laminography is associated with the study of defects occurred in the process of contact fatigue loading [39–41]. Other methods of synchrotron studies including diffraction methods are also used to solve this problem [42, 43]. Nakai et al. [41] studied bearing steel. Table 4 shows the composition of this steel. Loading was carried out according to the rolling contact fatigue (Fig. 18). A 24×10×1 mm sample was cut from a forged and spheroidized ingot with a diameter of 65 mm. The increased sulfur content in steel made it possible to study cracks that appeared near Fig. 15. Sample cut from a welded joint obtained by friction stir welding. The red circles are the fields of view of laminography [38] Fig. 16. The reconstructed synchrotron radiation computed laminography 3D image and a photograph of the fatigue crack [38]
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