PSI - Issue 51

Tereza Juhászová et al. / Procedia Structural Integrity 51 (2023) 213–218 Author name / Structural Integrity Procedia 00 (2022) 000–000

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(a)

(b) (b) Fig. 4 Comparison of the linear dependency of SIF-FCGR relation for AISI 304 and AISI 304 for different stress ratios: 0.1 (a), 0.3 (b) and 0.5 (c).

The results do not show significant variance, but it can be observed that the values of m grow with stress ratio for both grades. The values show greater size for grade of AISI 304 than for AISI 316 in every case. This can be interpreted as faster crack growth in this material, once the threshold value is reached. On the other hand, values of the constant C were lower, which means that smaller crack growth rate necessary for the propagation to start. The result can be connecter to the mechanical properties, especially toughness, which is higher for grade AISI 316.

Table 3. Paris' law constants for stainless steel grades AISI 304 and AISI 316 Stainless steel grade Stress ratio R [-]

m [-]

C [mm/no of cycles MPam 1/2 ]

AISI 304 AISI 316 AISI 304 AISI 316 AISI 304 AISI 316

0.1 0.1 0.3 0.3 0.5 0.5

3.176 2.594 3.324 2.613 3.619 3.302

9.331 × 10 -9 5.170 × 10 -8 2.368 × 10 -9 5.024 × 10 -8 1.242 ×10 -9 4.814 × 10 -9

Note that the results presented are a part of a more complex (numerical + experimental) analysis on stainless steels components; see for instance works as etc. Juhászová et al. (2023), Klusák et al. (2022, 2023), Seitl et al. (2022a), Seitl et al. (2022b), Seitl et al. (2023).

3. Conclusion In this contribution, FCGR of IPE 80 beams made of AISI 304 stainless steel and AISI 316 were analyzed. Three specimens were tested of each grade under three-point bending, each of them with various stress ratios R (0.1, 0.3 and 0.5). To evaluate the experimentally obtained data, a numerical model in the ANSYS Mechanical APDL software was created according to real measurements. The linear part of the evaluated experimental data (SIF vs. FCGR) was evaluated using power function in double logarithmic scale, which lead to interpretation of Paris’ equation. The obtained results of the material parameter m show higher values of the crack growth rate for grade of AISI 304 than for AISI 316, which also correspond to the values of material hardness according to Brinell. The dispersion of the values does not show a significant trend. These results could be interpreted as faster crack growth with lower hardness