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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．
The critical stress of rupture potential (Ecri) of LC4 aluminum alloy in 0.5 mol / L NaCl aqueous solution (pH = 7) at 30 ℃, 50 ℃ and 90 ℃ was -720mV, 760mV, -850mV (SCE). Stress corrosion cracking does not occur when the system potential is negative to Ecri. Ecri moves in the negative direction as the temperature T of the medium increases, and Ecri is generally in a linear relationship with T: Ecri = -A155-2.17T (mV). A modified simulated occlusion cell was used to investigate the chemical state of the crack tip: when the anode current density into the occluded region was 1mA / cm2, the pH value of the solution dropped from 7 to 3.3 and the concentration of Cl- was up to 4. The fracture is a typical intergranular stress corrosion cracking morphology.