Differences in Structure Evolution of Twin-Roll Cast AA8006 and AA8011 Alloys during Annealing

摘要

Thin aluminium sheets for many applications should exhibit high formability balanced by good strength. Sheets produced by continuous twin-roll casting (TRC) and cold rolling begin to displace ingot cast and hot rolled materials, but improvement of their formability is desirable. Detailed understanding of the structure evolution during thermo-mechanical processing is necessary in order to effectively optimise alloy properties and production technology. A study of the structure transformations in TRC AA8006 and AA8011 alloys during annealing in a temperature range 20 -605 deg C is presented. Thermo-electric power (TEP) and resistometric measurements, TEM and metallographic analyses were used. Second phase precipitation and particles redissolution at high temperatures were observed. Interaction between phase transformations and matrix softening is discussed. The results indicate that Mn addition significantly affects Fe and Si solubility and thus the kinetics of solid solution decomposition and structure transformation during annealing.