Al-Zn-Mg 合金の腐食疲労におけるカソード防食効果

概要

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Cathodic protection and damages due to hydrogen embrittlement under excess cathodic current have been discussed on the basis of experiments on fatigue lives of Al-Zn-Mg alloy in saline. Cathodic potentials increase the fatigue lives, the optimum protection being obtained under E=-1.3〜1.4V against a saturated calomel electrode. On the contrary the lives decrease under more negative potentials than E=-1.4V. Cathodic potentials between corrosion potential and E=-1.3〜1.4V suppress electrochemical corrosion, which leads to the delayed crack initiation and propagation. Fatigue striations are reformed from a brittle type to a ductile one by the application of the cathodic potentials, striation spacing also being decreased at the same time. Under the potentials more negative than E=-1.4V, the hydrogen embrittlement due to excess H^+ brings the enhanced crack initiation and the second appearance of a brittle type striation. Macroscopic fracture morphology also varies with the cathodic potentials, a shear mode macroscopic crack extention being replaced with a tensile one under the cathodic potentials.
社団法人日本材料学会の論文
1975-12-15