Jaguar is studying the potential of 7000 series aluminium alloys with a view to using the material in future models.
Although there are 'no plans at present' to use the high-strength aluminium material, it remains a long-term option of engineers to use the material to save body structure weight. Most likely areas of application will be A and B pillars and other areas where high strength is required. Both XJ and XK models use aluminium body shells.
Work is progressing in the laboratory to perfect 7000 Series materials suitable for both presswork and manufacturing, most notably materials joining.
The ideal material for automotive engineers is an alloy with the formability of 5754 alloy but with the strength of 7000 Series alloys.
In this context, Jaguar engineers are seeking an alloy in the range of 400 to 500MPa; this compares with the 250 to 300MPa strength of present-day aluminium alloys.
The 7000 series alloys in weight-saving mode would offer the same performance as 6000 series alloys but with a lower gauge thickness. But the increased hardness of 7000 Series alloys has important implications for process engineers. For example, the XJ Jaguar uses Henrob self-piercing rivets to join adjacent pressings. The increased hardness could require changes to the design of the rivet and its material specification, as well as impose a thickness limitation in terms of joint 'stack-up‘. Rivet guns may require further development to cope with the increased workload of the higher-strength alloys.
It is possible that a switch to 7000 series alloys could lead to other forms of material joining, including ultrasonic.
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