Historical Evolution of Thermomechanical Processes Applied to Aluminium Alloys

Abstract

Thermo-mechanical processing (TMP), coined 50 years ago for steels to describe combined thermal and mechanical treatments that define both product shape and microstructure/properties, has been practiced since the early industrial revolution. The improved function and control in mechanical shaping equipment were easily adapted to newly discovered aluminum, integrating hot forming, cold deformation and annealing. The TMP goals for Al alloys were grain refinement, substructure preservation, texture control and enhanced precipitation. Hot extrusion became widely employed with exploitation of elongated grains with substructure and strong texture and of press heat treatment (solution during deformation, quenching upon exit). Rolling schedules were tuned to generate desired grain size/shape, substructure and texture. This historical account aims to enhance application of metallography to process optimization and innovation that makes metals more competitive with other materials.