PSI - Issue 39

Atroshenko S.A. et al. / Procedia Structural Integrity 39 (2022) 3–8 Author name / Structural Integrity Procedia 00 (2019) 000–000

7

5

Fig.6. Spectrum of elements of the marked areas.

Area 2. The intermediate stage of destruction. The onset of an internal longitudinal crack defect is microcracks from accumulations of nonmetallic inclusions elongated during rolling in the form of path lines, which are visible in the microstructure photo (Fig. 7a).

a) b) Fig. 7. The origin of microcracks from lines along the rolling (a x500) and microcracks (b x1000).

Area 3. The initial stage of destruction . The structure of the initial fracture region is lamellar perlite with a rather fine grain (Table 3) (Fig. 8), in some places of which there are emerging microcracks along the lines from rolling (Fig. 8b). Microanalysis showed a large amount of sulfur and oxygen in the area of microcracks, which confirms the nucleation of microcracks on non-metallic inclusions.