EFFECT OF SUPERPOSED SMALL LOADS ON THE FATIGUE CRACK PROPAGATION RATE AT AN ANODIC POTENTIAL
阳极电位下小幅载荷在腐蚀疲劳裂纹扩展中的作用

The effect of small loads superposed upon principal cyclic load ?P on the fatigue crack growth rate da/dN has been studied for A537 steel in 3.5%NaCl solution at an anodic potential, and in air for comparison. The influence of anodic dissolution on small load behaviour has been discussed. The results showed that, anodic dissolution could increase the effect on da/dN of small loads superposed on the bottom of ?P obviously. In air condition, the small loads on the bottom with amplitude below 30%?P had little influence on da/aN caused by the principal load; whereas even the small loads with amplitude of zero enhanced the crack growth in anodic dissolution condition. When small loads with amplitude of 30%?P and 70%?P superposed on the top of ?P, although the results at an anodic potential did not show much difference from that in air, the small loads with amplitude of zero could accelerate crack growth. The effect of T0 was greater than that of B0.