Papers by Keyword: 6xxx

Abstract: Today, innovative lightweight constructions increasingly demand for profiles with higher strength and stiffness. In this investigation an axially moveable stepped mandrel allowed the manufacturing of load adapted (tailored) aluminum tubes with axial variable wall thicknesses by the extrusion process. Thus, on the one hand it is possible to produce thick-walled sections for highly stressed areas and on the other hand save profile weight by applying reduced wall thicknesses in areas with lower loads. Varying the extrusion ratio along tube direction affects the product velocity as well as the profile exit temperature und thus the microstructure in different tube sections. At high temperatures and high strain rates the microstructures revealed very large grains due to static recrystallization. However at low temperatures and low strain rates dynamic recovery lead to a microstructure dominated by fibrous grains. Small equiaxed grains were also found indicating geometric dynamic recrystallization.

Abstract: Aluminium is already extensively used in car production to reduce the CO₂ emissions by weight reduction. A further beneficial effect of lightweight design can be generated in components of the chassis by reducing the weight of unsprung mass thereby enhancing the driving comfort and reducing the noise level. The medium strength alloys of the type AlMg3Mn (EN AW-5754) and AlMg3.5Mn (EN AW-5454) are currently the aluminium sheet material choice for application in chassis components. The newly developed alloy AMAG AL6-CHA was optimized with regard to chassis applications and shows the potential of significant increase of the mechanical properties compared to state-of-the-art 5xxx series alloys. AMAG AL6-CHA, which is a 6xxx series alloy with balanced Mg/Si-ratio, is characterized with regard to mechanical properties and intergranular corrosion resistance in delivery temper T4 and after artificial aging with the typical heat treatment cycle 205 °C/60 min in peak aged temper T6. Furthermore we will show the results of the Charpy-V-notch impact test and the formability is described per bend test and grain size analysis.

Abstract: The final microstructure of extruded profiles is of great importance for final mechanical properties and, consequentially, the ability to control and predict it is of extreme interest for Academic and Industrial researchers. In the paper a combined model, able to discern recrystallized areas respect to fibrous structures within the same profile, is initially proposed then validated through FEM implementation on an experimental campaign performed by Parson [1]. The model was tested under different die geometries and process conditions and a qualitative comparison with final microstructure obtained in the extrusion of a simple aluminum rod was performed.

Abstract: To predict strength evolution of precipitation hardening alloys, a wide range of modelling approaches have been proposed. The most accurate published models are physics-based approaches which use both nanoscale processes with their related constants and parameters, as well as parameters calibrated to one or more macroscale measurements of yield strength of one or more samples. Recent developments in submodels including analytical expressions for volume fraction and size evolution including impingement and coarsening are reviewed. It is also shown that Kampmann-Wagner and JMAK models are generally not consistent with data on the progress of precipitations in the main precipitation hardening Al alloys systems, and improved model formulations are described.