Billet quenching extrusion process as efficient and reliable replacement for conventional extrusion of Al–Cu alloys

Abstract

In order to eliminate the separate solution soaking treatment used for Al–Cu extrudates, the influence of billet heat treatments before the extrusion process on a precipitation hardenable AlCu6PbBi (AA2011) alloy was studied. The hot deformation behaviour of the alloy was studied using compression tests. A comparison of the conventional extrusion process, press quenching and billet quenching (BQ) before extrusion was made in production on a 35 MN press. The transformation kinetics was studied by heat treating homogenised samples in salt baths. The mechanical testing, using tensile tests and the Brinell hardness test, and a microstructural investigation, using light and TEM microscopy, revealed that extrusion using the billet quenching process results in the formation of extrudates with similar mechanical properties, hardness and microstructures as those produced using conventional technology. In the extrudates produced by BQ a supersaturated solid solution is formed directly after cooling in a standing water wave, which makes BQ an efficient and reliable substitute for the conventional extrusion process.