Further insights on the stress equilibrium method to investigate macroscopic residual stress fields: case of aluminum alloys cylinders

Abstract The stress equilibrium, SE, method has been shown to be a very powerful, reliable tool for calculating the un-stressed lattice parameter, a0, as a critical requirement for the determination of the residual stress, RS, by diffraction techniques. The method can be used in cases where others, such as the powder or comb ones, are limited (e.g., in age-hardenable aluminum alloys components, where a0 can be affected). Owing to its potential, this method can address complex cases that, however, have not yet been sufficiently exploited. In particular, it makes it possible to delve into the effect of microstructural factors (e.g., texture variations) on the macroscopic residual stress, M-RS. Here, the M-RS obtained after quenching and slow cooling of cylindrical samples of aluminum alloys has been investigated. Data obtained from neutron and synchrotron radiation diffraction in AA5083 and AA2014 alloy samples (of different size), respectively, have been used. Specifically, the development of a texture gradient, a very common consequence derived from conventional manufacturing processes of components, has been taken into account. The known fact that a parabolic profile of the M-RS is obtained in cylindrical samples is used to generalize the SE method to determine a0 and to strengthen its quality and reliability.