Effect of sulfuric acid anodizing on mechanical properties of 2E12 al-alloy

2E12 Al-alloys without and with an Al-clad layer were treated via the traditional sulfuric acid anodizing process, so that an anodic oxide film was prepared on their surface. The effect of the Al-clad layer and anodic oxidation time on the surface morphology and mechanical properties of the anodic oxide films was investigated by means of morphological characterization, tensile property test and fatigue life test. The results showed that the dissolution of the second phase in the matrix of 2E12 Al-alloys can result in the formation of voids on the surface oxide film during the anodic oxidation process. With the increasing oxidation time, the thickness of the oxide film gradually increases, whilst the number and size of voids also increase. After sulfuric acid anodizing, the tensile property of 2E12 Al-alloy keeps basically unchanged, but the fatigue life decreases obviously. For the sulfuric acid anodized 2E12 Al-alloy without Al-clad layer, the fatigue life decreases to 30% of that for the counterpart. After the anodic oxidation treatment, the fatigue cracks originate from the defects of the oxide film surface, and the fatigue fracture shows multiple crack characteristics.