Validation of Simulated Material Flow in Aluminium Hot Extrusion with a Novel Visualisation Method

Abstract

Commonly used visualisation methods for observing material flow during extrusion are either labor intensive, prone to loss of the tracer pattern or subject to different flow behaviour than occurs in practice. A novel visualisation method using a copper mesh inlay and computer tomography was developed and used to visualise the flow behaviour of partially extruded EN AW-6082 aluminum billets. In parallel with the physical experiments, a finite element (FE) model was developed and compared with the experiments. The material flow was readily observable from the computer tomography images and the FE model data closely matched the experimental results.

Material Flow Visualization for Metal Extrusion on near Industrial Scale

“…This correlates with the secondary deformation zone [1] which is caused by the accumulation of the shell material during the extrusion process at the back of the billet. The reason for the lack of debris in this zone -in contradiction to [3,4] -is the fact that in this setup, and also in [5], markers do not reach the thin area near the billet surface. Due to the sticking of billet material at the container wall this thin area forms the secondary deformation zone during the extrusion process.…”

“…Then, they are sheared off, see markers near the tear off region in Fig. 5 left and [3,4]. This and further destruction of the torn off markers produces debris which also follows material flow.…”

“…For the investigation of material flow in extrusion processes the inscribed matrix visualization method is commonly used [1]. Improvements of this method based on the Inscribed Grid Pattern (IGP) and Pin Grid Pattern (PGP) methods which are presented in [2] lead to further research work by LKR [3,4]. At those improvements continuous copper wires (joint IGP-PGP method) or a continuous copper mesh (Mesh Grid Pattern (MGP) method) [3,4] are applied onto the meridian section of an extrusion billet and are detected by computed tomography (CT) as a non-destructive investigation method.…”

“…The main advantage of the latter method is the feasible determination of quantitative strain in the extruded profile additional to the flow behaviour of the material inside of the container including the influence of wall friction on the material flow [1]. This is possible since at the PCGP method cross shaped copper markers with a specific distinctive cross geometry instead of the inscribed grid, inserted pins [1,2], continuous wires or mesh [3,4] are deformed.…”

“…Previous work [3][4][5] was conducted at a semi-industrial scale extrusion press at LKR. In this work the upscaling of the PCGP method from semi-industrial to near-industrial scale is investigated to evaluate the feasibility of this method for industrial use.…”