加载波形对工业纯铁在3.5％NaCl溶液中疲劳裂纹扩展的影响

INFLUENCE OF LOADING WAVEFORM ON FATIGUE CRACK GROWTH FOR INDUSTRIAL IRON IN 3. 5%NaCl SOLUTION

研究了外加电位与加载波形对工业纯铁在3.5%NaCl中性水溶液中疲劳裂纹扩展的影响。外加电位正于-1000mV(SCE)时,腐蚀疲劳裂纹扩展为阳极溶解机制,负于-1000mV(SCE)时为氢脆机制。自腐蚀电位(-540mV)下,加载波形对腐蚀疲劳裂纹扩展影响按正锯齿波、正弦波、方波、负锯齿波依次减弱。各种加载波形条件下,裂纹尖端材料的动态应变行为不同导致阳极溶解行为各别,持续动态应变会加速阳极溶解过程.

The effects of applied potentials and loading waveform on the fatigue crack growth for industrial iron in 3.5%NaCl solution were studied.The corrosion fatigue (CF) crack growth is dependent on the applied potentials.Anodic dissolution plays an important role above a potential of—1000mV (SCE),while below this potential hydrogen embrittlement predominats.At free corrosion potential,anodic dissolution controls CF crack growth.The influence of loading waveform on the CF crack growth rate decrease in the order:positive sawtooth,sinusoid,square and negative sawtooth.It was suggested that the different of crack tip results in the difference of CF crack growth rate,i.e.,flow deformation enhances anodic dissolution at the crack tip.