Corrosion Fatigue Crack Growth under Stress Intensity Factor in Steel.

在控制应力强度因子和恒载荷幅的条件下，对3%盐水中的疲劳裂纹行为进行了实验研究。着重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。1）由于腐蚀产物对裂纹闭合有明显的楔效应，腐蚀对疲劳裂纹扩展的影响可以用裂纹扩展速率da/dN与有效应力强度因子的关系大于da/dN与应力强度因子的关系。2）随着应力比的增大，腐蚀产物的楔作用减弱，有效应力强度因子范围接近名义应力强度因子范围在几种负载循环频率和水温的组合下进行tess，发现在3%盐水中的生长速率在某些情况下几乎可以是空气中的7倍。利用上述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.