Hydrogen desorption activation energy and trapping sites associated with TiN particles in ferritic steel

The objectives of this study are to measure the activation energy ( E a ) of H desorption from TiN particles in ferritic steel and to identify their specific H trapping regions. TiC-containing specimens were used as references to validate the TiN results. H desorption rate peaks associated with incoherent TiC and semi-coherent TiN particles appeared at temperatures above 500 °C in the thermal desorption analysis curves. Based on the peak temperatures and Kissinger plots, the E a of the TiN specimen was determined to be ∼75.2 kJ/mol, which is lower than that of the TiC specimen (∼83.4 kJ/mol). In both specimens, H atoms were trapped at the particle-matrix interfaces, indicating that these interfaces are the predominant H trapping sites. It is believed that fine TiC particles provide high resistance to hydrogen embrittlement, in contrast to TiN particles, which are more susceptible to microcracking.