Influence of solution heat treatment on mechanical response and fracture behaviour of aluminium alloy sheets: An experimental study

摘要

Solution heat treatment (SHT), as a part of a consolidated process involving quenching and artificial ageing, significantly affects the mechanical properties of AA6082 sheets. In this study, SHT temperature and time were analysed as main design variables. Specimens were subjected to SHT by using central composite design and then processed by water quenching and artificial ageing (190 ℃/3 h). Tension tests were conducted at room temperature to measure the tensile strength and formability of the specimens. Response surface models for ultimate tensile stress (UTS) and ductility were constructed as a function of the design variables. UTS generally increased and ductility decreased with increasing SHT temperature and time. This result was processed using the multi-objective sorting genetic algorithm NSGA-Ⅱ to optimise design parameters and improve UTS and ductility. Pareto optimal solutions corresponding to UTS and ductility and appropriate ranges of design variables were obtained. The fracture characteristics of the alloy parts formed after tensile tests were further analysed using scanning electron microscopy. The fracture mode was the ductile fracture. Increasing SHT temperature and time made the dimples to be shallow and less.