PSI - Issue 43

Stanislav Seitl et al. / Procedia Structural Integrity 43 (2023) 113–118 Author name / Structural Integrity Procedia 00 (2022) 000 – 000

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the surface and the lowest value 211 in the middle of the bar. Analogous measurements of the hardness on the remaining bars showed that the hardness is constant across the cross section (in the frame of the measurement scatter). According to ISO 18265-2003, the Vickers hardness can be recalculated to ultimate tensile strength R m . In Tab. 5, the comparison of calculated and experimentally determined values is presented. The tensile properties of the PL20 E were partially better than the rest of studied bars, but with high values of relative standard deviation 6.67 %; this is in accordance with HV 0.1 measurements.

Table 5. Comparison of AISI 304 properties for different bars from different producers. AISI 304 PL20-E PL10-E PL20-A

PL10-A

HV 0.1

241 773 757

233 749 740

236 758 698

253 812 707

R m (HV 0.1) [MPa] R m [MPa] average

5. Conclusion Microstructure and mechanical properties of two types of flat bars from austenitic steel AISI 304 delivered by two producers were experimentally determined. The following conclusions can be drawn. • The microstructure of the investigated steels has grain size in a broad range 10 - 14 0 μm and a small amount of δ -ferrite (up to 5 %). The material A contains a lot of deformation twins (due to straightening of the semiproduct) • The Vickers hardness HV 0.1 of the investigated steels is in relation to the tensile properties of the material and ranges from 211 to 312. • The PL20-E bar exhibits different mechanical properties across the bar cross-section, whereas the PL10 E, PL20-A and PL10-A are from this point of view homogeneous. • Despite the fact that the tested bars meet the strength standards, it is advisable to perform an indicative hardness measurement on the material used for a reliable design of the structure. Acknowledgements The financial support of the Brno University of Technology project No. FAST-J-22-7959 and from Czech science foundation project no. 20-00761S (Influence of material properties of stainless steels on reliability of bridge structures) is greatly appreciated. References Gardner, L., 2005. The use of stainless steel in structures, Progress in Structural Engineering and Materials 7(2), 45 – 55. Gardner, L. 2019. Stability and design of stainless steel structures — Review and outlook, Thin-Walled Struct., 141, 208 – 216, Baddoo, N.R., 2008. Stainless steel in construction: A review of research, applications, challenges and opportunities, J. Constructional Steel Research 64(11), 1199 – 1206. Gedge, G., 2008, Structural uses of stainless steel — buildings and civil engineering, Journal of Constructional Steel Research 64(11), 1194 – 1198. Kala Z., Omishore A., Seitl S., Krejsa M., Kala J., 2017, The effect of skewness and kurtosis on the probability evaluation of fatigue limit states, International Journal of Mechanics, 11, 166 – 175 Kala Z., Seitl S., Krejsa M., Omishore A., 2019, Reliability assessment of steel bridges based on experimental research, AIP Conference Proceedings, 2116, art. no. 120005 Krejsa, M., Brozovsky, J., Lehner, P., Seitl, S. Kala, Z., 2018, Stochastic analysis for short edge cracks under selected loads”, AIP Conference Proceedings 1978, 150006. Seitl, S., Pokorný, P., Klusák, J., Duda, S., Lesiuk, G. , 2022, Effect of Specimen Thickness on Fatigue Crack Growth Resistance in Paris Region in AISI 304 STEEL Fatigue and Fracture of Materials and Structures. Structural Integrity, Vol. 24. Springer Seitl S., Miarka P., Klusák J., Fintová S., Kunz L. , 2018, Comparison of the fatigue crack propagation rates in S355 J0 and S355 J2 steel grades, Key Engineering Materials, 784, 91 – 96 Seitl S., Miarka P., Klusák J., Kala Z., Krejsa M., Blasón S., Canteli A.F. , 2018, Evaluation of fatigue properties of S355 J0 steel using ProFatigue and ProPagation software, Procedia Structural Integrity, 13, 1494 – 1501