Fatigue behaviour of aluminium alloys after anodic and plasma-electrolytic oxidation
Final Report Abstract
To meet the requirements of the specific application field regarding tribological properties, an electrochemical conversion treatment is an effective method to improve the corrosion and wear resistance of aluminum alloys. By anodization, the surface of the metallic substrate is converted to an oxide ceramic layer with excellent adhesion to the substrate without affecting its microstructure. The structure of the formed coating as well as the achievable coating thickness are determined by the process. Depending on the requirement profile, the conversion layer is generated by an anodic (EAO) or a plasma-electrolytic (PEO) oxidation process. However, a major disadvantage of oxide ceramic coatings is the resulting reduction in fatigue strength. This effect is attributed to the brittle and porous nature of the oxide ceramic coatings, in particular, and pre-damage of the coatings resulting from the conversion process, for example thermally induced cracks, which promotes premature failure. The results of the project contribute to the understanding of the effective relationship between conversion layer type, fatigue strength in the HCF regime and the coating damage mechanisms. The conversion type-related coating structure and the coating thickness were identified as significant factors influencing the fatigue strength. In particular, plasma-electrolytic coatings have a high potential for an optimized property profile under cyclic loading by a specific adjustment of the process parameters. The findings of the project can enable the expansion of the application fields of conversiontreated substrates in the future.
Publications
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Schwingfestigkeit und Mittelspannungsempfindlichkeit der Legierung AlMgSi1 nach hochgradig plastischer Umformung und anodischer bzw. plasmaelektrolytischer Oxidation. Juli 2020, Eigenverlag: Werkstoffe und werkstofftechnische Anwendungen, Band 87; Herausgeber: Univ.-Prof. Dr.-Ing. habil. Thomas Lampke. ISBN: 978-3-949005-01-5. ISSN: 1439-1597.
Winter, L.
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Steigerung der Schwingfestigkeit einer konversionsbehandelten AlMgSi1-Legierung durch eine ECAP-Umformung des Substrates. WOMAG 12 2020, S. 4-6; ISSN 2195-5905.
Winter, L. & Lampke, T.
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Schwingfestigkeit einer hochgradig plastisch umgeformten, konversionsbehandelten AlMgSi-Legierung. ZVOreport 1 2021, S. 44-45.
Winter, L. & Lampke. T.
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Influence of Hydrothermal Sealing on the High Cycle Fatigue Behavior of the Anodized 6082 Aluminum Alloy. Coatings, 12(8), 1070.
Winter, Lisa & Lampke, Thomas
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Fatigue Resistance of an Anodized and Hardanodized 6082 Aluminum Alloy Depending on the Coating Thickness in the High Cycle Regime. Advanced Engineering Materials, 25(20). Portico.
Winter, Lisa & Lampke, Thomas
