应力比对D36钢腐蚀疲劳裂纹扩展的影响  

Effect of Stress Ratio on Corrosion Fatigue Crack Growth Rate of D36 Steel

作　　者：代娇荣 黄一[1] 吴智敏[1] 

机构地区：[1]大连理工大学建设工程学部,大连116024

出　　处：《腐蚀科学与防护技术》2016年第2期109-114,共6页Corrosion Science and Protection Technology

摘　　要：采用三点弯曲实验研究应力比R对处于不同环境下的D36钢稳定裂纹扩展区疲劳裂纹扩展速率的影响。结果表明,空气中应力比对pairs区的疲劳裂纹扩展速率影响不大,然而海水环境中,在中等△K值范围内,应力比对裂纹扩展速率影响较空气中明显,且其裂纹扩展速率随着应力比的增加而增大。这种现象产生的原因是氢脆作用随着应力比的增大显著增强。通过三电极体系在f=1 Hz,R=0.1条件下分别对试件施加-400,-600,-800,-1000和-1200 m V的电极电位。结果表明,强阴极极化(-1200 m V)和阳极极化(-400 m V)在一定△K范围内会加速裂纹扩展,综合得出该条件下腐蚀疲劳的阴极保护电位为-800 m V。而应力比为0.3和0.5时施加-800 m V的电极电位对材料的保护作用减弱。The effect of stress ratio R on the fatigue crack propagation rate（FCPR） of D36 steel was investigated in air and sea water with different applied potentials. The results reveal that by a given applied cyclic stress intensity △K in air, the da/d N-ΔK curve exhibits a slight change in fatigue crack propagation rate with the increase of stress ratio. However, by intermediate △K values,the increase of the fatigue crack propagation rate is obvious in sea water, which may be ascribed to the hydrogen embrittlement. With applied potentials with in a range from-400 to-1200 m V onto the test steels at f=1 Hz, R=0.1, it follows that with the potential corresponding toeither the over-cathodic protection（-1200 m V） or the anodic dissolution（-400 m V） conditions the corrosion fatigue crack propagation rate（CFCPR） will be accelerated within a certain △ K range, and therewiththe optimal protection potential of-800 m V is identified. But the protection effect by the applied potential-800 m V was weakened with the increase of the stress ratio from 0.3 to 0.5.

关 键 词：应力比R D36钢 腐蚀疲劳 阴极保护电位 疲劳裂纹扩展速率 

分 类 号：TG172[金属学及工艺—金属表面处理]