加载波形对D36钢腐蚀疲劳裂纹扩展速率的影响

Influence of Loading Waveforms on Corrosion Fatigue Crack Growth for D36 Steel

对标准单边缺口三点弯曲试样分别施加三角波、正弦波、方波3种波形,得到了不同波形作用下的腐蚀疲劳裂纹扩展曲线,研究了在不同电位条件下加载波形对海水中D36钢腐蚀疲劳裂纹扩展速率(da/d N)的影响。结果表明:无阴极保护时,三角波和正弦波作用下试样的疲劳裂纹扩展速率相当,并小于方波作用下的疲劳裂纹扩展速率,且方波的加速作用体现在低应力强度因子幅度时;在阴极保护条件下,这种现象更为明显;而在阳极极化条件下,方波对试件的疲劳裂纹扩展的加速作用减弱。

The corrosion fatigue crack growth curves were measured under triangle,sinusoidal and square waveforms using gaps unilateral standard three-point bend specimens.The influence of loading waveforms on corrosion fatigue crack growth rate（CFCGR）for D36 steel was studied in natural seawater solution at different applied potentials.The results show that the CFCGR under sinusoidal waveform was the same as that under triangular waveform and was lower than the value under square waveform without cathodic protection.The acceleration of square waveform was more noticeable in the low stress intersity factor range.Under cathodic protection condition,the difference of the CFCGR between square waveform and sinusoidal waveform became wider.Whereas,the acceleration of square waveform on fatigue crack growth rate was reduced under anodic polarization condition.