Analysis of hydrogen embrittlement susceptibility of H2ICE components

Hydrogen embrittlement (HE) leads to significant materials degradation, given by dissolved hydrogen that detrimentally affects the mechanical properties of metals, including ductility, toughness, and strength. The present study addresses HE in internal combustion engine (ICE) (General Motors) parts sourced from Dumarey. The motive is to reveal the susceptibility to HE of IC engine parts in hydrogen-rich environments. The research methodology integrated a comprehensive literature review of hydrogen-metal interactions with targeted experimental evaluations. Materials were subjected to electrochemical hydrogen charging, followed by slow strain rate tensile (SSRT) testing at a strain rate of 10−5 s−1 to quantify variation in mechanical performance. Post-mortem analyses involved scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) followed by detailed fractographic analysis. Key findings revealed variation in the responses under hydrogen environment. Al-Si alloy from the engine head exhibited a significant reduction in ductility (∼67%) with a mixed-mode fracture. In contrast, the Al-Si piston blank displayed an atypical increase in ultimate tensile strength and elongation, despite both charged and uncharged specimens shown inherently low ductility. Grey cast iron from the engine block demonstrated increased brittleness, with reductions in both ultimate tensile strength and ductility (∼31%). Ductile cast iron from the exhaust manifold showed minimal strength loss but an unexpected increase in ductility after hydrogen charging, a result warranting further investigation. A central theme emerging from this work is the critical influence of microstructural features, particularly the nature, density, and distribution of hydrogen trap sites such as Si particles and intermetallic phases in Al-Si alloys, and graphite morphology and carbides in cast irons, on the overall HE susceptibility. These findings bear considerable importance for the informed selection and design of materials intended for application in emerging hydrogen-based IC engines.