【摘要】 <正> 到目前为止,对Ⅱ型试样的氢致开裂和应力腐蚀还没有进行深入的研究。本文用超高强钢Ⅱ型缺口试样,研究Ⅱ型试样能否产生氢致开裂,研究氢致裂纹的形核位置及方向,从而加深了对氢致开裂机理的研究。同时,用有限元8节点等参元法计算了缺口前端的应力场,并用之对实验结果进行了定量分析。实验过程超高强度钢34CrNi3MoA成分为(wt-％):C=0.33,Si=0.25,Mn=0.67,Cr=0.93,Ni=2.80,Mo=0.34,其余为Fe。试样加工更多还原

【Abstract】 Hydrogen induced cracking (HIC) of a high strength steel 34CrNi3MoA (TS=1700 MPa) under mode Ⅱ loading was investigated using notched specimens. The stress field around the notch tip was analyzed by means of finite element method. The result shows that the HIC under mode Ⅱ loading initiates at the back of the notch tip, i. e., θ=-110°, where hydrostatic stress has the maximum value. However, cracking is oriented along the shear stress direction at the site, not normal to the direction of maximum principal stress component. On the contrary, if the specimens are loaded to fracture in air under mode Ⅱ loading cracking at the maximum shear stress site around the notch tip and the cracking direction coincides with the direction of the maximim shear stress. The facts above mentioned indicate that hydrogen induced delayed plastic deformation is a necessary condition for HIC.更多还原