The Optimum Process to Produce High-Strength Cast/Forged Al–8%Zn–2.5%Mg–1%Cu Alloy

Abstract

Al–8Zn–2.5Mg–1Cu alloy casting blocks were subjected to homogenization and annealing. The treated blocks were then held at different temperatures and forged in different dies to obtain 20 mm-thick plates. After T73 heat treatment, the plates were cut and machined to obtain tensile bar samples that were further subjected to tensile and potentiodynamic polarization tests. Upon analyzing the experimental results, the subzero-treated and forged samples (SO) developed fine grains in their matrix and displayed yield stress (YS) about 400 MPa and an elongation of 11%. The hot-forged samples (HC) displayed a relatively higher YS slightly >440 MPa and a lower elongation of 4%. The intermetallic compound particles confined to the HC decreased its corrosion resistance to be worse than that of the SO. All anodized and sealed samples effectively improved their corrosion resistance. Due to its fine grains, the anodized SO sample produced a higher Icorr than the anodized HC sample.

Microstructures and Macrosegregation of Al–Zn–Mg–Cu Alloy Billet Prepared by Uniform Direct Chill Casting

“…The Al–Zn–Mg–Cu alloy with a high strength-to-density ratio, considerable fracture toughness and good stress corrosion cracking resistance has been widely used for military and commercial applications [ 1 , 2 , 3 , 4 , 5 , 6 ]. Despite its positive characteristics, the main bottleneck for this alloy is how to prepare large-sized high quality billets or ingots for final applications of forging or extrusion.…”