Hydrogen Diffusion and Trapping in Ultrahigh-Strength AerMet 100

AerMet 100 is a new generation ultrahigh-strength steel (UHSS) and is currently specified for manufacturing important aircraft parts such as landing gears. As a UHSS, AerMet 100 is susceptible to internal hydrogen embrittlement (IHE) and the mechanisms are complicated due to the trapping H transport interactions, given the fine-scale microstructural features serving as potential trap sites (dislocations, precipitates, undissolved metal carbides, martensite lath interfaces, etc.). The present investigation is aimed at understanding the role of traps as storage sites for H that could repartition to crack tips, with emphasis on trap state analyses, binding energy estimations and the association with specific microstructural features of AerMet 100. It is also sought to understand residual trap occupancy as a result of baking condition as well as the impact of such residual H on susceptibility to IHE.