Flexible Hot Rolling of Extruded Shapes of Aluminum Alloy EN AW-6082

Olexandr Grydin,Teresa Behr,Mirko Schaper,Anatolii Andreiev,Andrii Samsonenko,Mykhailo Stolbchenko,Nikolay Sotirov,Nikolay Biba,Iaroslav Frolov

doi:10.4028/www.scientific.net/msf.949.85

Abstract

One of the strategies employed to lower weight and to decrease material consumption is reducing part thickness itself. Thus, functionally graded materials in which structural reinforcement is adjusted locally, are of great interest. With regard to conventional industrial processes, such as extrusion or flexible cold rolling, thickness variations can only be achieved either longitudinally or through the cross-section of the semi-finished products. Hence, a combined thickness variation (along both axes) is difficult to generate solely by extrusion or rolling. A simultaneous thickness variation in both directions, however, would enable further weight savings in structural components such as car body parts. In this study, a promising approach with extruded shapes, serving as a billet for a flexible hot rolling process, is elaborated upon. By employing the described process modification, shapes with simultaneous thickness variations in longitudinal as well as in transverse direction are feasible. Initial numerical analysis reveals the weight-saving potential of using these semi-finished products for structural parts in a car body. A demonstration of the production process for the semi-finished parts and the occurring challenges are discussed. To verify and adjust the new technology, a numerical model of the flexible hot rolling process has been created based on the finite element software QForm VX. This model is also employed for tool design optimization to produce semi-finished components with the required geometrical quality. Finally, the results of hot rolling experiments conducted using the adjusted roll design are presented.

Highlights

As automakers have sought to lower weights and reduce the use of materials in modern car components, aluminum and its alloys, which simultaneously exhibit relatively low density and a wide variety of properties, are being increasingly applied due to their lightweight potential
In the case of nominal rolling reduction of 30 %, the reduction of element 2 amounts to 0 % because its initial thickness is less than the rolling gap of «X + 1.2» mm; in the case of a rolling reduction of 50 %, it amounts to approximately 7 %
This means that the material in the area of element 2 is not being elongated due to compression as a result of rolling reduction, but is rather being plastically stretched by neighboring elements 1 and 3 due to the higher compression and simultaneous elongation of these elements

Summary

Introduction

As automakers have sought to lower weights and reduce the use of materials in modern car components, aluminum and its alloys, which simultaneously exhibit relatively low density and a wide variety of properties, are being increasingly applied due to their lightweight potential Another strategy employed in addition to lightweight material is reducing the volume of a part by varying the part’s thickness to provide additional structural reinforcement only where it is necessary. One of the well-studied and established industrial processes to produce thickness variation in a single sheet or shapes is extrusion, during which variation of thickness can primarily be achieved in transverse direction [1] Another production process, which allows thickness variation in either the longitudinal or transversal direction, is flexible rolling [2] or strip profile rolling [3]. Both processes are already well-studied and industrially approved, they do not allow sheets to be produced with simultaneous thickness variation in both transverse and longitudinal directions.

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