The influence of homogenization heat treatment on microstructure development in Al-Mn alloy AA5454

摘要

The material studied in this work is the Al-Mn-Mg alloy AA5454, produced by the VAW Aluminium Company, Bonn, Germany, and used for the manufacture of automotive construction components. The material is supplied to the automotive manufacturer in the form of hot rolled coil, approximately 8mm in thickness. The thermomechanical processing history of the alloy controls the microstructure of the product as it is supplied to the customer. The purpose of this work is to understand the underlying mechanisms that control the microstructure of the alloy, by characterisation of the evolution of precipitate species and their effect on static recrystallisation. To this end, electrical conductivity, differential thermal analysis and electron microscopy measurements have been carried out at various stages in the processing route. The conditions of the homogenisation heat treatment have been varied, and the effect on subsequent recrystallisation after hot rolling has been evaluated in both the as-cast and rough-rolled condition by optical microscopy techniques. Results indicate that the conditions of homogenisation heat treatment and roughing rolling appear to be critical for the generation of a suitable microstructure in this alloy.