PSI - Issue 68

Birhan Sefer et al. / Procedia Structural Integrity 68 (2025) 1129–1139 Author name / Structural Integrity Procedia 00 (2025) 000–000

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mechanical properties for CGI at room temperature can be ascribed to the presence of diffusible hydrogen measured in the specimen. In contrast, no diffusible hydrogen peak was measured in the CGI specimens tested at high temperature. Similar TDS data for cast iron with multiple hydrogen peaks was also presented by Trola et al. (2023). For SiMo51 no obvious reasonable correlation of the hydrogen distribution and contents with the mechanical behaviour was possible to establish. For example, properties of SiMo51 were notably affected by hydrogen at room temperature accompanied with fractographic analysis that evidenced brittle failure, but not obvious hydrogen uptake was measured to support this result. On contrary, SiMo51 showed uptake of strongly trapped hydrogen at high temperature, however the properties were deteriorated to similar extent as at room temperature where no uptake was measured. Finally, the hydrogen analysis is also supportive to the SSRT results obtained from the tests at room temperature for NCF3015 material. No hydrogen uptake was measured for this specimen, in agreement with the observation that hydrogen have not caused degradation of the mechanical properties of the NCF3015. No effect on the properties of NCF3015 was neither observed for the tests carried out at high temperature. The significant hydrogen uptake of strongly trapped hydrogen seems to not have strong effect on the properties of NCF3015. 4. Conclusions In this study we investigated the mechanical degradation due to hydrogen gas at high pressure at room and high temperatures of conventional metallic materials commonly utilized for manufacturing diesel internal combustion engine and exhaust components. The main conclusions derived from this work are as follows: • The SiMo51 material exhibited a significant loss of mechanical properties due to hydrogen at room and high temperature. • The compact graphite iron (CGI) material showed greater sensitivity to hydrogen at room temperature compared to high temperature. This conclusion was supported and in agreement with the observations from the fractographic and hydrogen analysis for the CGI material. • Among the tested materials, the properties of NCF3015 was least affected by hydrogen for both at room and high temperature. • The hollow specimen method proved to be a useful tool for screening the influence of pressurised hydrogen on mechanical properties at room and high temperature. However, this method was not suitable for testing the SiMo51 at high temperature at 200 bar pressure with the present specimen geometry • The results from this study show that further research is needed to determine if the investigated materials for exhaust and diesel engine components are suitable for use in hydrogen combustion. In particular, SSRT testing at other pressure and temperatures regimes in both Ar and H 2 is recommended. In addition to SSRT testing, obtaining data for the fatigue properties is also of importance to capture better the effect of the service conditions on the integrity of these materials. Acknowledgements The authors acknowledge the Swedish funding agency Vinnova (Diarienr: 2022-01587 Projekttitel: Vätgasinducerade degradering av mekaniska egenskaper i nya applikationer - HYMECH II) for providing financial support of the work presented in this paper. The authors would also like to acknowledge Peter Skoglund from Scania, Sweden for his support in planning and writing the paper. Finally, the authors acknowledge Oliwer Gustavsson from Swerim AB for performing all the SSRT testing presented in this paper. References Cho, Y-G., Lee, K-S., 1989. The Effect of Hydrogen on the Mechanical Properties of Cast Irons and ADI with Various Carbon Equivalent and Graphite Morphology. Journal of the Corrosion Science Society of Korea, 18 (4), 233-244. Matsunaga, H., Usuda, T., Yanase, K., Endo, M., 2013. Ductility Loss in Ductile Cast Iron with Internal Hydrogen. Metallurgical and Materials Transactions 45A, 1315-1326. Matsuno, K., Matsunaga, H., Endo, M., Yanase, K., 2012. Effect of Hydrogen on Uniaxial Tensile Behaviours of a Ductile Cast Iron. International Journal of Modern Physics: Conference Series 6, 407-412. Matsuo, T., 2017. The effect of pearlite on the hydrogen-induced ductility loss in ductile cast irons. IOP Conf. Series: Journal of Physics: Conf. Series 843, 012012