Hydrogen trapping and desorption of dual precipitates in tempered low-carbon martensitic steel

The hydrogen trapping behaviors of dual nanometer-sized epsilon-copper and TiC carbide precipitates have been investigated in a low-carbon steel. The precipitation fashions were controlled by quenching and tempering at different austenization temperatures. The nanostructures of the dual precipitates were characterized by high-resolution transmission electron microscopy and atom probe tomography. Hydrogen desorption was studied through thermal desorption analysis of steels electrochemically charged with hydrogen. The hydrogen trapping capability of the precipitates was investigated through the release process. The precipitation routes of TiC carbides influenced the behavior of hydrogen trapping and the co-precipitation of copper and TiC carbides significantly increased the hydrogen trapping capability of the steels. These heat treatments can therefore be used to tailor the resistance to hydrogen embrittlement in tempered martensitic steels. Importantly, co-precipitated TiC and epsilon-copper particles in tempered martensitic steels show an enhanced capacity for hydrogen trapping and provide a range of trapping strengths. Co-precipitation is therefore proposed as a new prospect for designing steels with the capacity for substantial hydrogen trapping. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.