Interactions between Pre-strain and Dislocation Structures and Its Effect on the Hydrogen Trapping Behaviors

This work investigated the effect of pre-strain and microstructures and their interactions on hydrogen trapping behaviors in case of 1-GPa high-strength martensitic steel Fe-0.05C-0.30Si-1.10Mn-3.50Ni-0.53Cr-0.50Mo-0.03 V (wt%). We found that the trapped reversible and trapped irreversible hydrogen contents increased significantly after applying a pre-strain of 5%, with an increase in the trapped reversible hydrogen content from 0.6 ppm in the original sample to 2.1 ppm. The hydrogen desorption activation energy also showed a slight increase. The microstructural evolution revealed that the concomitant dislocation cell-twin duplex microstructure with high-density tangled dislocations after pre-strain substantially increased the trapped reversible hydrogen contents. Additionally, the tangled dislocations pinned by the nanoprecipitates acted as deep irreversible hydrogen traps, increasing the trapped hydrogen at high temperatures after applying 5% pre-strain. These findings provide an expanded understanding of the hydrogen trapping behaviors of pre-strained microstructures.