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采用微电极体系和试样背后打孔技术,对300M超高强度钢在3.5％NaCl水溶液中腐蚀疲劳裂纹尖端微区溶液电化学行为进行研究。在极化和无极化条件下分别测试裂尖溶液的电位ΔE和pH值的变化。结果发现,无极化条件下,裂尖pH下降,电位上升,裂尖前沿电位和pH值随裂尖扩展而分布不均匀;在极化条件下,裂尖电化学特征随极化电位变化而表现不同。基于裂尖电化学行为规律,对腐蚀疲劳裂纹扩展规律进行解释。
The microelectrode system and the puncturing technique behind the sample were used to study the electrochemical behavior of 300M ultrahigh-strength steel in the solution of corrosion fatigue crack tip micro-zone in 3.5% NaCl aqueous solution. The changes of potential ΔE and pH of the tip solution were tested under polarized and non-polarized conditions respectively. The results showed that under the condition of nonpolarization, the pH value at the crack tip decreased and the potential increased. The front potential and the pH value at the crack tip were unevenly distributed with the crack tip. Under the polarization condition, the electrochemical characteristics of the crack tip were changed with the change of the polarization potential different. Based on the behavior of crack tip electrochemical behavior, the law of corrosion fatigue crack propagation is explained.