Determination and control of bonding properties in aluminum composites in the combination of compound casting and forming
Final Report Abstract
The determination and control of the interface character of aluminum bilayer billets over the process chain of compound casting and extrusion were analyzed within this project. This process route exhibits resource benefits compared to classic solid-to-solid joining processes. The intial bonding at the interface of bilayer products is achieved in the casting operation. A tailored process control of the subsequent massive forming allows to homogenize the interfacial bonding, eliminate voids, which are characteristic for cast products, and increase the bonding strength through an additional solid-to-solid contact of the joining partners generated under high plastic deformation. The investigations were conducted using primarily bilayer billets consisting of AA7075 (core material) and AA6060 (shell material). The formation of solid solutions and diffusion processes lead to formation of a cohesion in the casting operation. Despite the established cohesive bonding after casting, the predominant characteristic of the interface after massive forming attributes to solid state bonding led by the plastic deformation at elevated temperatures. The different process steps were accompanied by simulation studies. These helped to extract key figures to evaluate the technological potential of each operation. Engineering approaches were defined based on the analysis of the stress distribution in as-cast and extruded billets. These allow to link the process steps. Thus, negative output results can be compensated and positive results can be improved. The present study represents a comprehensive description of an exemplary process route for the production of hybrid metallic products. The findings are based on thermophysical, thermomechal and chemical examinations and were achieved through theoretical, experimental and numerical studies.
Publications
- (2019): Mechanical Characterization of As-Cast AA7075/6060 and CuSn6/Cu99.5 Compounds Using an Experimental and Numerical Push-Out Test, Materials Science and Engineering: A 751, 214-225
Greß, T., J. Stahl, T. Mittler, L. Spano, H. Chen, N. Ben Khalifa, W. Volk
(See online at https://doi.org/10.1016/j.msea.2019.02.080) - (2019): Thermal Analysis and Production of As-Cast Al 7075/6060 Bilayer Billets, International Journal of Metal Casting 13(4), 817-829
Greß, T., T. Mittler, S. Schmid, H. Chen, N. Ben Khalifa, W. Volk
(See online at https://doi.org/10.1007/s40962-018-0282-8) - (2020): Production of Aluminum AA7075/6060 Compounds by Die Casting and Hot Extrusion, Journal of Materials Processing Technology 280, 1-12
Greß, T., T. Mittler, H. Chen, J. Stahl, S. Schmid, N. Ben Khalifa, W. Volk
(See online at https://doi.org/10.1016/j.jmatprotec.2020.116594)
