Influence of processing on the properties of the aluminium alloy 2025 with a zirconium addition

摘要

The influence of hot deformation and alloy composition on the tensile properties, tear toughness and exfoliation corrosion susceptibility of aluminium alloy 2025 forgings has been investigated. Two casts of 2025 were used to make extrusion billets. These were of standard composition within the 2025 specification, and a composition outside the permitted range but reflecting more modern alloy design with a 0.12 wt.% addition of zirconium. Billets were hot extruded and hot forged at a range of temperatures expected to produce unrecrystallised, partially and fully recrystallised microstructures. The main objective of the compositional variation was to alter the wrought grain refining intermetallic phase, allowing more control of the grain size produced by heat treatment. After the application of a standard heat treatment, tensile and tear toughness properties were determined. Exfoliation tests were performed in accordance with ASTM-G34. The exfoliation susceptibility and mechanical properties of 2025 forgings have been found to exhibit a dependence on microstructure developed during hot forming and heat treatment but the Zr addition was ineffective in producing a refined microstructure.