Through thickness variations of deformation texture in round profile extrusions of 6063-type aluminium alloy: Experiments, FEM and crystal plasticity modelling

Abstract

The deformation texture and its through-thickness heterogeneity for an extruded round profile are experimentally measured by the electron back-scatter diffraction technique (EBSD), and numerically modelled by coupling FEM flow simulation and crystal plasticity simulations. Deformation histories are extracted from the FEM flow simulation. The billet material was a type of 6063 aluminium alloy. Small-scale round profiles were extruded at 300 °C in a lab extrusion setup featuring immediate water quenching at the end of deformation, keeping the profile essentially in the deformed state. The deformation texture is a strong <111> and weak <100> duplex fibre texture in the centre region, whereas the texture is weaker and rotated when approaching the surface. The full-constraint Taylor and the Advanced-lamel model (Alamel) were employed and evaluated for texture predictions. Both models give similar predictions as the experiments. The Alamel model performs better in terms of both global and through-thickness texture predictions. Analysing the deformation history from the FEM simulations reveals that the deformation condition is close to ideal uniaxial tensile deformation in the centre, whereas it is an approximate plane-strain deformation with superimposed simple shear deformation near the surface region. It is concluded that the texture through-thickness gradient can be successfully predicted by coupling FEM and Alamel model for the studied profile. The texture heterogeneity is mainly attributed to the deformation heterogeneity across the thickness.

Deformation Texture Evolution in Flat Profile AlMgSi Extrusions: Experiments, FEM, and Crystal Plasticity Modeling

“…It is well known that during uniaxial tension of fcc alloys, a double 〈100〉/〈111〉 fiber texture develops (Zhang et al, 2018b). Consistent with the deformation analysis above, this is also what is observed experimentally by analyzing the texture of the material in the container (of the AA6063 alloy extruded at 350°C) before it enters the die (not shown in this paper), with a double 〈111〉 and 〈100〉 fiber texture, where the 〈111〉 component is considerably stronger than the 〈100〉.…”

“…The deformation microstructure is characterized by its deformation substructure and associated texture. As already mentioned, coupled FEM simulations and crystal plasticity (CP) modeling has recently successfully been performed to provide texture predictions comparable to the experiments (Zhang et al, 2015;Zhang et al, 2018b). In principle, any CP model can be used, nonetheless advanced CP models such as Alamel-type models have shown to perform better than the FC-Taylor model in predicting the deformation texture.…”

“…The same modeling approach has recently been applied for the extrusion of round profiles of the same alloy (Zhang et al, 2018b). As compared to the previous work, only the center deformation path is considered for the subsequent texture simulations in the present work.…”

“…The deformation characteristics can be analyzed by means of the FEM flow simulations, using the same method developed by (Zhang et al, 2018b). Evolution of the strain rate along the center path is illustrated in Figure 2.…”

“…At the same time, it was shown that the predictions were improved by considering the nonoctahedral slip systems for high-temperature deformations. More recently, the present authors have modeled the overall deformation texture for extruded round profiles, using the FC-Taylor model and Alamel-type models and deformation histories along different particle paths provided by FEM flow simulations, to predict the through thickness texture variations (Zhang et al, 2018b). Compared to experiments, the Alamel model gave the best predictions.…”