Aluminum automotive body designs still incorporate steel for bumper beams, and steel-based crash systems predominate in rail applications. As part of the UK Lightweight Energy Absorbing Aluminium Structures for Transport (LEAAST) project, researchers are developing and demonstrating lightweight Al systems based on the use of a novel high strength Al extrusion alloy that can replace the incumbent steel systems.

The high-performance cast Al alloys are being advanced at the Brunel Centre for Advanced Solidification Technology (BCAST), an academic research center on the campus of Brunel University London, in concert with foundry partner Sarginsons Industries and others. The new material will provide at least a 25 percent weight reduction by using alloys formulated from recycled end-of-life scrap.

Two Al alloys have been developed within the project and have proven to be successful in industrial trials, with improved strength and ductility.Industrial trials at Sarginsons Industries of the BCAST-developed high-performance cast aluminium alloy using a Jaguar Land Rover component. (Source: Brunel University London)

The new 6xxx series wrought alloy can provide yield strength and elongation of more than 500 MPa and 10 percent, respectively. The 3xx series cast alloy is about 3 times lighter than steel and, compared with previous alloys, has yield strength of 310 MPa, ultimate tensile strength of 365 MPa, and elongation of 10 percent. This provides a ratio of strength to density that enables parts made from these alloys to absorb the required stresses and deform in a controlled manner under impact.

BCAST is focusing on recycling of Al alloys using melt-conditioned direct chill casting, and the overcasting technology, in which metals with lower melting temperature are cast over higher-melting alloys to optimize weight and performance.