2013 Volume 54 Issue 5 Pages 729-731
Carbide-free bainitic steel is a typical high-strength steel and it is very sensitive to hydrogen embrittlement. Studies have shown that the hydrogen embrittlement in bainitic steels was decreased by the addition of aluminium. However, hydrogen embrittlement still exists in these steels. The in-situ tension in transmission electron microscope (TEM) was used to observe and analyse the effect of hydrogen on the dynamic process of dislocation motion and crack nucleation in carbide-free bainitic steel. A special self-made constant deflection device was used to install the specimen in TEM. Before and after hydrogen charging, the movement of dislocations and microcracks can be clearly observed. The results showed that hydrogen can facilitate the emission, multiplication and motion of dislocations. It also demonstrated that hydrogen can enhance the microcrack nucleation, growth and connection of carbide-free bainitic steel.