PSI - Issue 17

Jan Klusák et al. / Procedia Structural Integrity 17 (2019) 576–581 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

580

5

The inclusion was analyzed by the energy dispersive spectroscopy (EDS) to gain its chemical composition. A significant amount of aluminium and oxygen is likely to indicate the fact that the inclusions could be created by impurities of Al 2 O 3 . As similar inclusions were observed as crack initiation points also in other specimens, it can be said that purity has significant impact on fatigue life of S355 steels.

Fig. 4: Surface crack initiation (left) and crack propagation (right) in S355 J0B (specimen no. 2 – N f = 1.4135  10 8 )

Fig. 5: Subsurface crack initiation (left) and the detail of the inclusion (right) in S355 J0A (specimen No. 4 – N f = 3.2590  10 6 )

5. Conclusions

Two grades of steel (S355 J0 and S355 J2) were analyzed by high frequency fatigue loading to get very high cycle fatigue properties. These two grades were analyzed in two perpendicular directions according to the direction