In the SFB 692 HALS (High-strength aluminum based lightweight materials for safety components), subproject B-3, the production of an aluminum magnesium compound by a hydrostatic co-extrusion process was investigated. The quality of these semi-finished products, especially the stability and robustness of the interface between the aluminum (AlMgSi1) sleeve and magnesium (AZ31) core, was of particular interest. Previous papers have described the first process optimization steps as the improvement of the die design as well as the numerical methods for identification of important process parameters and the development of a quality model for the interface. This paper describes the formability of such semi-finished products with subsequent forging processes, especially die forging. Therefore, two different die forging strategies were investigated. In the first approach the strand-shaped work piece, with a circular cross-section, was formed along its longitudinal axis with die forging. In the second approach the same geometry was radially formed with die forging. Thereby, the compound was formed in longitudinal direction up to an analytical equivalent strain value of 1.61 and in radial direction up to 1.38. First results showed that the interface of the aluminum magnesium compound is very stable and ductile enough to be forged. Dye penetration tests were performed to prove the stability of the interface in a first step. Then, micro sections were made to investigate the interface metallographically. No cracks or damages were detected with both test methods in the interface of the forged aluminum magnesium compound. Furthermore, numerical simulations were performed to analyze the forging processes in detail. Therefore, a full 3D simulation model was set-up with Forge2011 and the calibration was performed with the press force as well as the geometry aspects. The correlations between experiments and simulations are very well. By means of the calibrated simulation detailed analyses of interface section are performed and the stability of the interface was investigated. This shows that the compound quality reached by the hydrostatic co-extrusion process is very suitable for subsequent forming steps as die forging. The investigations show the potential of such hybrid compounds and clarify their application, especially in the automotive sector.
The changes of ecological awareness of political initiatives give new rules for economy and industry with the aim to support environmental friendly technology. Research projects are focusing on lightweight designs especially in automotive and aerospace industry. This paper deals with the results of the application of lightweight materials, in detail with aluminum-magnesium-compounds and its manufacturing process. Thereby, the process chain from the production of semi-finished parts and the first subsequent process will be explained in detail with focusing on the modification of the intermetallic interface. The combination of hydrostatic co-extrusion and subsequent performed forging is an auspicious approach for the production of lightweight parts made of Al-Mg-compounds. In this contribution the main influencing parameters, experimental and numerical work, interface properties as well as the process analysis will be explained in detail.
With respect to its density, magnesium (Mg) has a high potential for lightweight components. Nevertheless, the industrial application of Mg is limited due to, for example, its sensitivity to corrosion. To increase the applicability of Mg, a process chain for the production of a Mg component with a complete aluminum (Al) cladding is presented. Hydrostatic co-extrusion was used to produce bar-shaped rods with a diameter of 20 mm. The bonding between the materials was verified by ultrasonic testing. Specimens with a length of 79 mm were cut off from the rods and forged by using a two-staged process. After the first step (Heading), the Mg core was removed partially by drilling to ensure a complete enclosing of the remaining Mg during the second forging step (Net shape forging). The geometry of the drilling hole and the heading die design were dimensioned with the Finite Element-simulation software FORGE. Hence, a complete Al-enclosed Mg component was achieved by using the described process chain and forming processes. Microstructural investigations confirm the formation of an intermetallic interface as expected.
Die ersten Untersuchungen der hydrostatisch stranggepressten Al‐Mg Verbunde als Halbzeuge für Folgeprozesse wie Gesenkschmieden verdeutlichen das große Potenzial hybrider Werkstoffverbunde. Die experimentellen Analysen ergaben, dass die Grenzschicht ein hohes Umformvermögen aufweist. Mit verschiedenen Gesenkschmiedeoperationen konnten Umformgrade von 1,50 erreicht werden, ohne dass eine Schädigung in der Grenzschicht auftrat. Die numerischen Untersuchungen ergaben keine signifikanten Dehnungsunterschiede in der Grenzschicht und verdeutlichen somit die Stabilität der Zwischenschicht. Materialkennwerte der stranggepressten Einzelwerkstoffe wurden für unterschiedliche Temperaturen und Umformungsgeschwindigkeiten bestimmt, um zukünftig noch präzisere Simulationen zu ermöglichen.
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