Corrosion fatigue (CF) tests were conducted on a high strength steel,in 0.6M NaCl solution at 5 Hz, under the following loading ocnditions: (1) pure torsion,(2) pure push-pull,(3) torsion with superimposed axial static tension/compression,and (4) push-pull with superimposed static shear.Experimental test results obtained under torsional air fatigue loading show that axial tensile and compressive mean stress decreases and increases in fatigue endurance life respectively.However,in the presence of an environment,the effect of a biaxial mean stress ( sigma _m) on the torsional fatigue life is reduced when compared to that in air.In addition it was noted that push-pull corrosion fatigue life is unaffected by the application of a static shear stress ( tau _m),unlike that observed in air where push-pull fatigue life decreases on increasing the applied static shear stress.Using a plastic replication technique it has been found that the environment dominates stage I shear crack growth by controlling crack orientation and causing an acceleration in the crack growth rate.In the stage II crack growth regime both the loading stress-state and environment influence cracking.A two stage biaxial short fatigue crack growth model previously developed for the in-air condition was subsequently modified and applied to correlate corrosion fatigue crack growth rate and fatigue life data.
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机译：在以下载荷条件下，在5Hz的0.6M NaCl溶液中对高强度钢进行了腐蚀疲劳（CF）测试：（1）纯扭力，（2）纯推拉力，（3）轴向叠加扭力静态拉伸/压缩，以及（4）叠加有静态剪切的推拉。在扭转空气疲劳载荷下获得的实验测试结果表明，轴向拉伸和压缩平均应力分别降低和增加了疲劳耐久性寿命。在环境中，与空气相比，双轴平均应力（sigma _m）对扭转疲劳寿命的影响减小了。此外，还注意到推拉腐蚀疲劳寿命不受静态剪应力的影响（ tau _m），这与在空气中观察到的情况不同，在空气中观察到的推拉疲劳寿命会随着施加的静态剪应力的增加而缩短。使用塑性复制技术，发现环境在第一阶段的剪切裂纹扩展中占主导地位。在第二阶段裂纹扩展状态下，加载应力状态和环境都会影响裂纹。随后建立了一个先前针对空气条件的两阶段双轴短疲劳裂纹扩展模型修改并应用于关联腐蚀疲劳裂纹扩展速率和疲劳寿命数据。
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