Corrosion Fatigue Crack Growth under Stress Intensity Factor in Steel.

试验研究了在控制应力强度因子和恒定载荷a幅值条件下，混凝土在3%盐水中的疲劳裂纹行为。重点研究了裂纹张开载荷、频率和试验温度对裂纹扩展速率的影响。所得结果总结如下：1)由于腐蚀产物的楔形作用对裂纹闭合有显著的影响，因此用裂纹扩展速率da/dN与有效应力强度因子范围的关系比用da/dN与应力强度因子范围的关系更能看出腐蚀对疲劳裂纹扩展的影响。2)随着应力比的增大，腐蚀产物的楔形作用减小，有效应力强度因子范围趋近于法向应力强度因子范围。3)在负荷循环频率和水温的几种组合下，发现在某些情况下，3%盐水中的生长速率几乎是空气中的7倍。利用上述技术，加速试验可能成为可能。

Behavior of fatigue crack in 3% salt water is experimentally examined under the condition of controlled stress intensity factor as well as constant load a amplitude. The emphasis is placed on the effects of crack opening load, frequency and test temperature on the crack growth rate.The results obtained are summaraized as folloes;1) Since there is notable effect of wedge action due to the corrosion products on the crack closure, the influence of corrosion of the fatigue crack growth can be seen in much better fashion with the diagram of the crack growth rate da/dN vs. the effective stress internsity factor range than that of da/dN vs. the stress intensity factor range.2) As the stress ratio increase, the wedge action of the corrosion product decreases and the effective stress intensity factor range approaches to the nomonal stress intensity factor range.3) Performing tess under several combinations of load cycle frequencies and water temperatures, it is found that the growth rates in 3% salt water can be almost seven times as large as those in air for some cases. Making use of the above an accelerated test may become possible.