PSI - Issue 51

Lucia Pastierovičová et al. / Procedia Structural Integrity 51 (2023) 135 – 140 L. Pastierovi č ová et al. / Structural Integrity Procedia 00 (2022) 000–000

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Table 1. Chemical composition of experimental A357.0-T6 alloys according to the delivery list from UNEKO, Ltd [wt. %]

Fe

A357.0-T6

Al

Si

Cu

Mn

Mg

Zn

Ti

Na

Other Rem. Rem. Rem.

0.128 0.202 0.429

A B C

92.372 92.286 91.774

6.742 6.675 7.097

0.012 0.018 0.013

0.046 0.058 0.044

0.519 0.564 0.466

0.005 0.021 0.002

0.108 0.113 0.119

0.005 0.006 0.003

From the experimental bars, 2 sets consisting of 15 cylindrical specimens were prepared for fatigue testing under rotating bending according to the STN 42 0363 standard documented in Fig. 1. The fatigue tests were performed on the experimental device for rotation-bending fatigue testing under the same testing conditions with different stress amplitude of 67 Hz, 77 Hz and 87 Hz, frequency at 32 Hz, a load ratio of R = -1 at room temperature T = 21 ± 1 °C. The fatigue life of all specimens was determined to be 1.0 × 10 6 cycles according to UNEKO, Ltd demands.

Fig. 1. Specimen dimensions for fatigue testing under rotating bending.

The fatigue life was analyzed using S-N curves. For simultaneous testing of specimens with corrosive environment, a 3.5 % NaCl solution was prepared and connected to the specimen using specific grips so the same area of the specimen was exposed to the corrosive environment. After finishing the fatigue test by specimen fracture, each specimen was rinsed with ethanol and dried to avoid further influence of the corrosive environment on the fracture surface and immediately observed using SEM. 3. Results and discussion The fatigue life evaluation of experimental alloys with different Fe contents in two different states (in non-chloride and 3.5% NaCl solution) was performed in the high cycle fatigue region. The number of cycles to fracture increases with decreasing stress amplitude of 88 MPa, 78 MPa and 68 MPa for all alloys. The fatigue testing in non-chloride environment, fatigue life decreases with increasing Fe, see Fig. 2.

Fig. 2. S-N curves for A357.0-T6 in non-chloride environment.