The effects observed in engineering materials after annealing and ageing processes

This paper presents an experimental evaluation of the effects induced in the selected engineering alloys (brass and aluminium alloy) by annealing and ageing. Both materials were tested in the as-received state and after annealing. In the case of brass, an influence of the ageing process on the subsequent mechanical properties under complex monotonic loading was also investigated. An analysis of the experimental data is based on the concept of the yield surface determined in the two-dimensional stress space (σ, τ). The materials in the as-received state exhibit an initial anisotropy coming from the manufacturing processes applied to produce rods used as the blanks for specimens. In order to remove the initial anisotropy, a few different types of the annealing processes were applied. To assess an evolution of the mechanical properties of brass due to the ageing process, the subsequent yield surfaces were determined after different time periods measured with respect to the annealing. It was shown that the residual stresses removed from brass using the annealing process arose again in this material due to the ageing phenomenon which took place during the long-term storage at room temperature.