AISI 321 stainless steel is widely used in hydrogenation refining pipes and hydrogen storage vessel and so on owing to its excellent performance of creep stress resistance and high-temperature resistance. In this study, slow strain rate tensile tests (SSRT) were conducted under the condition of electrolytic hydrogen charging (EHC). The hydrogen embrittlement mechanism of AISI 321 stainless steel was analyzed in detail by means of scanning electron microscopy(SEM), X-ray diffraction spectrometer (XRD) and transmission electron microscope (TEM). The results show that hydrogen can change the fracture mode of tensile specimens from ductile fracture to brittle fracture mode. The main reason is that dislocations slide carrying hydrogen continuously in the material under the action of slow strain rate stress, resulting hydrogen cracks are preferentially produced at austenite grain boundaries, inclusions and the interface between δ ferrite and austenite. Additionally, it is easy to induce the transformation and growth of α' martensite in the process of hydrogen charging and reduce the plasticity of the material.

AISI 321不锈钢因其出色的抗蠕变应力性能和耐高温性能而被广泛用于加氢精制管和储氢容器等。在这项研究中，在电解氢充注（EHC）的条件下进行了慢应变速率拉伸试验（SSRT）。通过扫描电子显微镜（SEM），X射线衍射光谱仪（XRD）和透射电子显微镜（TEM）对AISI 321不锈钢的氢脆机理进行了详细分析。结果表明，氢气可以将拉伸试样的断裂模式从韧性断裂转变为脆性断裂模式。主要原因是位错在慢应变速率应力的作用下在材料中连续滑动携带氢，由此产生的氢裂纹优先在奥氏体晶界，夹杂物和δ铁素体与奥氏体之间的界面处产生。另外，在充氢过程中容易诱发α'马氏体的相变和生长，并降低材料的可塑性。