采用控制电位下的恒载荷拉伸试验测得ＬＣ４铝合金在３０℃、５０℃、９０℃的０．５ｍｏｌ／ＬＮａＣｌ水溶液（ｐＨ＝７）中的应力腐蚀临界破裂电位Ｅｃｒｉ分别为－７２０ｍＶ、－７６０ｍＶ、－８５０ｍＶ（ＳＣＥ）．体系电位负于Ｅｃｒｉ时不发生应力腐蚀破裂．Ｅｃｒｉ随介质温度Ｔ升高而向负方向移动，Ｅｃｒｉ与Ｔ大体呈直线关系：Ｅｃｒｉ＝－Ａ１５５－２．１７Ｔ（ｍＶ）．用改进的模拟闭塞电池研究了裂纹尖端化学状态的变化：当通入闭塞区的阳极电流密度为１ｍＡ／ｃｍ２时，其溶液ｐＨ值从７降至３．３，Ｃｌ－浓集倍数高达４．断口呈典型的沿晶应力腐蚀开裂形貌．
Constant load and potentiostatic techniques were used to study the critical SCC potential of aluminium alloy LC4 in 0.5mol/L NaCl solution. It was found that the critical potentials for this system at 30℃, 50℃, 90℃ are -720mV, -760mV, -850mV (SCE), respectively, below which the SCC will not occur. The dependence of the critical potential upon temperature follows a linear equation: Ecri=-655-2.17t (mV). The simulated occluded corrosion cell was modified and used to investigate chemical changes within stress corrosion cracks. When an anodic currellt of 1mV/cm2 was passed through, the pH value of the occluded cell solution dropped down from 7 to 3.3 and the faCtor of Cl- enrichmeat in the solution could be up to 4. Scanning electron fractographs of SCC of alloy LC4 showed a typical intergranular cracking feature.
参考文献
| [1] | |
| [2] | SpeidelMO．ThetheoryofStressCorrosionCrackinginAlloys,ed．SoullyJ．C |
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