导出了使裂纹脆性扩展的外加应力场强度因子K_I和断口分形维数D_F的关系式其中d_f是断裂单元尺寸,L_o是常数,γ是真实表面能,E’=E或E/(1-v~2)测出1nk_1-D_F直线就可获得真实表面能γ、此方程适用于过载断裂和滞后断裂(如氢致开裂和应力腐蚀) 实验表明,Ti—24Al—HNb在动态充氢时能发生氢致滞后断裂,且门槛值较低,K_(IH)/K_(IC)=0.43实验测出的K_(IC)和氢致裂纹扩展的外加应力场强度因子K_I与其断口D_F的关系和上述理论公式一致 The relationship between the strength factor K_I of external stress field and the fractal dimension D_F of fracture is derived, in which f_f is the fracture unit size, L_o is constant, γ is the real surface energy, E ’= E or E / (1-v ~ 2), the real surface energy γ can be obtained by measuring the straight line 1nk_1-D_F. This equation is suitable for overload and delayed fracture (such as hydrogen induced cracking and stress corrosion). Experiments show that Ti-24Al-HNb can occur during dynamic hydrogen charging Hydrogen induced delayed fracture, and the threshold value is low, KI (IH) / K IC (IC) = 0.43 The relationship between K_ (IC) and applied stress field strength factor K_I and fracture D_F of hydrogen induced crack growth measured by the above theory The same formula