Trap-governed hydrogen diffusivity and uptake capacity in ultrahigh-strength AERMET 100 steel

摘要: The hydrogen-uptake capacity and mobility in ultrahigh-strength AERMET 100 are characterized for various electrochemical charging baking conditions. From thermal desorption spectroscopy, the apparent hydrogen diffusivity (D H < 3 × 10−8 cm2/s at 23 °C) is over tenfold less than values typical of tempered martensitic steels such as AISI 4130. value D decreases with decreasing temperature below 200 °C, a relatively high activation energy diffusion 17.7 to 18.8 ± 0.2 kJ/mol 95 pct confidence level. also diffusible concentration from less-severe or increased baking. Potentiostatic saturated Ca(OH)2 produced total concentrations which increase (H+/H) overpotential significantly higher results 4130 steel under same A significant was by zero deposition. These characteristics explained extensive reversible irreversible trapping involving least three unique trap states ultrafine microstructure. former likely include coherent M2C carbides, soluble Ni, precipitated austenite, latter larger incoherent M x C y martensite lathed-packet interfaces. Baking °C removes lowest binding-energy sites, but reduced levels prolong outgassing time. Additionally, substantial retained stronger states. effects pertinent embrittlement steel.