Study on multiple container extrusion-rolling process for producing thin wide aluminium sheet material
File(s)
Author(s)
Li, Weishu
Type
Thesis
Abstract
Thin-wide sheet of aluminium alloys has a wide range of applications, particularly in the automotive industry, and has thus attracted significant research in recent years. The mass-production of this sheet material is fulfilled through a series of hot and cold rolling operations and is costly due to expensive plant and repeated heating. Extrusion is an alternative method for producing thin-wide aluminium sheet, but the conventional process requires very large extrusion forces, and this problem has not been fully addressed in any previous studies.
In the present work, a new technology is proposed to enable extrusion of thin-wide aluminium sheets. This new method combines a novel multi-container extrusion process, which significantly reduces the force required for extrusion, with subsequent rolling operations, which gives greater microstructural uniformity and improves weld quality through additional vertical deformation of the as-extruded material. The extrusion ratio and force are reduced by using multiple small containers (multiple small, paralleled cylinders through a container block) with a small contact area between billets and rams, instead of a single large container, as in the conventional case.
In the present work, a lab-scale experimental extrusion system using three small containers is designed and manufactured. The extrusion tests are conducted on the AA6061-T4 material under different extrusion temperatures and speeds. The subsequent rolling treatment is performed at different temperatures and with different rolling thickness reductions on the materials extruded under the same conditions. Microstructural characterisation using optical microscopy (OM) and electron backscatter diffraction (EBSD) techniques and room-temperature tensile testing on extruded and extruded-rolled materials are performed to investigate the effects of process parameters on both the microstructure evolution and the mechanical properties of the processed materials. The weld quality between billets under each condition is studied according to their tensile properties and welding seam shapes of extruded and extruded-rolled specimens...
In the present work, a new technology is proposed to enable extrusion of thin-wide aluminium sheets. This new method combines a novel multi-container extrusion process, which significantly reduces the force required for extrusion, with subsequent rolling operations, which gives greater microstructural uniformity and improves weld quality through additional vertical deformation of the as-extruded material. The extrusion ratio and force are reduced by using multiple small containers (multiple small, paralleled cylinders through a container block) with a small contact area between billets and rams, instead of a single large container, as in the conventional case.
In the present work, a lab-scale experimental extrusion system using three small containers is designed and manufactured. The extrusion tests are conducted on the AA6061-T4 material under different extrusion temperatures and speeds. The subsequent rolling treatment is performed at different temperatures and with different rolling thickness reductions on the materials extruded under the same conditions. Microstructural characterisation using optical microscopy (OM) and electron backscatter diffraction (EBSD) techniques and room-temperature tensile testing on extruded and extruded-rolled materials are performed to investigate the effects of process parameters on both the microstructure evolution and the mechanical properties of the processed materials. The weld quality between billets under each condition is studied according to their tensile properties and welding seam shapes of extruded and extruded-rolled specimens...
Version
Open Access
Date Issued
2023-06-26
Date Awarded
31/08/2023
License URL
Advisor
Shi, Zhusheng
Lin, Jianguo
Publisher Department
Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)