Quantitative investigation on deep hydrogen trapping in tempered martensitic steel

In this work, the correlation between different microstructural components and hydrogen trapping with high density in tempered niobium carbide (NbC)-precipitated martensitic steel was quantitatively investigated using a combination of electrochemical hydrogen permeation experiments and thermal desorption spectroscopy. The martensite lath and a high density of dislocations, which constitute the reversible hydrogen trapping sites, with a density of 2.24 x 10(20) cm(-3) in Fe-0.05C-1.10Mn-4.50Ni-0.50Cr-0.50Mo-0.05Nb wt.% martensitic steel. The dislocation with high density could disperse the hydrogen distribution. Furthermore, the uniformly distributed NbC nanoprecipitates, the high-angle grain boundaries, and the grain-boundary precipitates were found to act as irreversible hydrogen traps, with a density of 1.00 x 10(20) cm(-3). These deep hydrogen trapping sites could not only trap hydrogen irreversibly, but also can inhibit the accumulation of hydrogen. The interpretation of hydrogen trapping is significant to enhance the hydrogen embrittlement resistance of high-strength martensitic steels. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study quantitatively investigated the correlation between different microstructural components and high-density hydrogen trapping in tempered niobium carbide (NbC)-precipitated martensitic steel. It was found that martensite lath and a high density of dislocations served as reversible hydrogen trapping sites, while NbC nanoprecipitates, high-angle grain boundaries, and grain-boundary precipitates acted as irreversible hydrogen traps. These findings are significant for enhancing the hydrogen embrittlement resistance of high-strength martensitic steels.