The Evolution of Mechanical Properties and Microstructure in Early Stages of Natural Ageing on 2024 Plates

The evolution of plasticity of heat treatable alloys in W temper is important for an efficient stress releasing by stretching or compression (Tx51 and Tx52 tempers) but also for some special hardening operations that combine cold working and ageing practices. For the alloys that have a significant natural ageing, the environment temperature has an important influence. In order to evaluate the influence of this temperature, the mechanical properties and the microstructure were investigated at various temperatures between −10 and + 80 °C and ageing time between 0 and 80 h on plates in alloy EN AW 2024, using standard tensile tests, electronic microscopy and X Ray diffraction. The results demonstrate that from many standpoints (mechanical properties, plasticity, electrical conductivity, microstructure etc.) the ageing transformations end before the limit of 96 hours that is considered as standard.