The TTT and TTP Diagrams of Commercial Aluminum Alloys Used for Quenching Cooling and Ageing Regimes Optimization

摘要

Isothermal TTT and TTP diagrams were obtained for sheets from three commercial aluminum alloys: D16 (similar to 2024) of Al-Cu-Mg system, 6013 alloy of Al-Mg-Si-Cu system, 1424 alloy of Al-Li-Mg system. We used heat treatment that consists of direct annealing and direct ageing and as well as customary ageing after solution treatment (ST) and quenching. TTP diagrams were plotted by results of electrical conductivity and tensile properties. For TTT diagrams we used TEM, X-ray phase analysis, X-ray microprobe analysis and differential-scanning calorimetry (DSC). The relationships between hardening precipitates phase composition and properties were investigated. For each alloy, the comparison of TTT and TTP diagrams gives important information about the effect of strengthening phases on properties. The use of TTT and TTP diagrams for heat treatment optimization is discussed. Practical examples for the use of TTT and TTP diagrams for development of optimum quenching and combined (step) aging are given.