Screening the Mechanical Degradation of Combustion Engine and Exhaust Metallic Materials in High Pressure and High Temperature Hydrogen Gas Environment

This study investigated the impact of hydrogen gas (H 2 ) on the mechanical properties of conventional metallic materials used in Diesel Internal Combustion Engines (DICE) and exhaust components at room and elevated temperatures. Two conventional materials commonly used in the combustion section of a DICE such as compacted graphite iron (CGI) used in cylinder heads and the Fe-Ni-base alloy NCF3015 used in engine valves were included in the study as well as one material commonly used for exhaust components the cast iron SiMo51. To evaluate the impact of H 2 on the mechanical properties hollow specimens internally pressurized with 200 bar H 2 were tensile tested using slow strain rate (SSRT) and compared with inert gas (Ar) as reference. The results from SSRT were correlated to the fractographic analysis of the specimens post-testing using Scanning Electron Microscope (SEM). Additionally, thermal desorption spectroscopy coupled with a mass spectrometer (TDMS) was used to analyse hydrogen uptake after SSRT. Key findings from this work revealed significant property loss in SiMo51 material at both room and elevated temperature, while the CGI showed greater sensitivity at room temperature compared to elevated temperature. In contrast, for NCF3015, H 2 showed minimal impact on its properties. The study also showed that the hollow specimen method proved to be an effective tool for assessing the impact of H 2 on mechanical properties at both room and elevated temperature. This work highlights the need for further investigations to determine the performance of these materials for hydrogen combustion applications, including additional SSRT along with fatigue testing at varying pressures and temperatures.