Abstract

In the present work, the deformation textures during flat profile extrusion from round billets of an AA6063 and an AA6082 aluminium alloy have been numerically modeled by coupling FEM flow simulations and crystal plasticity simulations and compared to experimentally measured textures obtained by electron back-scatter diffraction (EBSD). The AA6063 alloy was extruded at a relatively low temperature (350°C), while the AA6082 alloy, containing dispersoids that prevent recrystallization, was extruded at a higher temperature (500°C). Both alloys were water quenched at the exit of the die, to maintain the deformation texture after extrusion. In the center of the profiles, both alloys exhibit a conventional β-fiber texture and the Cube component, which was significantly stronger at the highest extrusion temperature. The classical full-constraint (FC)-Taylor and the Alamel grain cluster model were employed for the texture predictions. Both models were implemented using the regularized single crystal yield surface. This approach enables activation of any number and type of slip systems, as well as accounting for strain rate sensitivity, which are important at 350°C and 500°C. The strength of the nonoctahedral slips and the strain-rate sensitivity were varied by a global optimization algorithm. At 350°C, a good fit could be obtained both with the FC Taylor and the Alamel model, although the Alamel model clearly performs the best. However, even with rate sensitivity and nonoctahedral slip systems invoked, none of the models are capable of predicting the strong Cube component observed experimentally at 500°C.

Highlights

  • Extrusion is an extensively used thermal–mechanical process to produce aluminium profiles for a range of applications

  • The deformation texture of the AA6082 alloy extruded at 500°C has been recorded (Figure 1B)

  • This alloy, even at this high extrusion temperature, is in a fibrous, nonrecrystallized state after extrusion, and can as such be compared with the AA6063 alloy extruded at 350°C

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Summary

Introduction

Extrusion is an extensively used thermal–mechanical process to produce aluminium profiles for a range of applications. In many cases, it is challenging to provide extruded profiles with a consistent and homogenous grain structure and texture both along the length and through the cross section of the profiles. It is, of great importance to understand and be able to predict (model) how different microstructures and textures are generated and how they evolve during and after extrusion, as basis for controlling the final. 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).

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