TEM IN SITU OBSERVATION OF BRITTLE CRACKING OF HYDROGEN CHARGED 310 STAINLESS STEEL UNDER TENSION
氢致脆断的TEM原位拉伸观察

The effect of hydrogen on the cracking of type 310 stainless steel was studied by TEM in situ observation of hydrogen-charged specimens and comparison with the hydrogen-free specimens.The results show that 1)in precharged specimens,many dislocations can emit from a crack tip followed by forming a dislocation free zone(DFZ) after equilibrium:2)nanocracks nucleate preferable in DFZs;3)microcracks connect with each other,resulting in the brittle cracks,instead of blunting into voids.The effect of hydrogen on the change from ductile to brittle is to prevent nanocracks in DFZs from blunting into voids.