IntoSitu TEM Study of HydrogentoInduced Cracking in CarbidetoFree Bainitic Steel

摘要

Carbidetofree bainitic steel is a typical hightostrength steel and it is very sensitivetohydrogen 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 intositu tension in transmission electron microscope (TEM) was usedtoobserve and analyse the effect of hydrogen on the dynamic process of dislocation motion and crack nucleation in carbidetofree bainitic steel. A special selftomade constant deflection device was usedtoinstall 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 carbidetofree bainitic steel.