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利用恒位移加载台,在TEM中原位研究了油管钢在充氢和水介质中应力腐蚀前后裂尖位错组态的变化.结果表明,氢能促进位错发射、增殖和运动,并使无位错区扩大.用激光云纹干涉法原位测量了充氢前后加载缺口前端位移场的变化,结果表明,氢能使缺口前端塑性区及变形量增大.TEM原位观察表明,当氢促进位错发射、运动达到临界条件时就引起纳米级氢致裂纹在无位错区中形核.探讨了氢促进位错发射、增殖和运动的原因以及氢致裂纹形核机制.
In the TEM, the dislocation configuration of the crack tip before and after stress corrosion in hydrogen-filled and aqueous media was investigated by using a constant displacement loading stage.The results show that hydrogen can promote dislocation emission, proliferation and motion, The dislocation region is enlarged.The change of the displacement field before and after the hydrogen charging is measured by in-situ laser moire patterning.The results show that hydrogen can make the plastic zone and the deformation amount increase at the front of the notch.TEM observation shows that when hydrogen Which promotes the dislocation emission and the nucleation of nanocrystalline hydrogen-induced cracks in the dislocation-free region when the motion reaches the critical condition.The reason why hydrogen promotes the dislocation emission, proliferation and movement as well as the nucleation mechanism of hydrogen induced cracking are discussed.