Effects of Low Temperature on Forged Steel Materials in Hydrogen Internal Combustion Engines Applications: Assessing Ductile-Brittle Transition

Hydrogen Internal Combustion Engine (H2ICE) has hydrogen gas storage system and is operated at very low temperature before it enters the combustion chamber. The effect of hydrogen on steel materials is detrimental because of hydrogen embrittlement. Forged steel parts are used in engine specifically valve. The goal of the work is to analyze the outcome of low temperature i.e. 35 °C to -30 °C on three types of forged steel materials i.e. 40Cr4, 42CrMo4 and EN8 and assess any potential changes in their properties due to ductile to brittle transition. Charpy impact test is widely used to determine the temperature at which a material shifts from exhibiting ductile behavior to brittle behavior. This transition is critical for understanding the safety and reliability of steel components, as brittle fracture can lead to catastrophic failures. The steel samples were subjected to six different temperatures and identified changes in the transition temperature and micrographs of the failed steel samples, such as shear area. The transition temperature was found to shift towards lower temperatures, indicating an increased susceptibility to brittle fracture. This shift in the transition temperature suggests that the steel used in engine parts may exhibit reduced fracture toughness and impact resistance when operating with hydrogen as a fuel. Based on the test results, steel grade 40Cr4 consistently exhibits the highest impact energy absorption across all testing temperatures, in contrast to steel grades 42CrMo4 and EN8. This highlights its superior toughness and suitability for various applications.