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本文研究了几种测定裂纹尖端溶液化学和电化学条件的方法。通过冷冻法和侧面放置微电极方法测定了裂纹尖端的pH值,利用底孔放置微电极方法测定了裂纹尖端的电位。利用人造裂缝装置研究了外加电位对裂纹尖端pH和电位的影响,可以看到随阴极极化的增加,裂纹尖端的电位朝负向移动,而裂纹尖端的pH值起初增加很缓慢,但当阴极极化低于-1000mV(SCE)时,pH值迅速增加。在阳极极化下,裂纹尖端电位几乎不受外加电位的影响,裂纹尖端的pH值维持不变。根据这些试验结果进一步研究了D6Ac钢应力腐蚀破裂的机理。
In this paper, several methods to determine the chemical and electrochemical conditions of crack tip solution have been studied. The pH value at the tip of the crack was measured by the freezing method and the microelectrode method. The potential of the tip of the crack was measured by using the microelectrode method. The effects of applied potential on the crack tip pH and potential were studied by means of an artificial fracture device. It can be seen that as the cathodic polarization increases, the potential at the tip of the crack moves in a negative direction, whereas the pH at the crack tip initially increases very slowly. However, When the polarization is below -1000 mV (SCE), the pH rapidly increases. Under anodic polarization, the crack tip potential is almost unaffected by the applied potential and the pH of the crack tip remains unchanged. Based on these test results, the mechanism of stress corrosion cracking in D6Ac steel was further studied.