The return to equilibrium of retained a phase powders during heating is analyzed using DTA, XRD, SEM and TEM. It takes place in three successive steps: firstly nanolamellar transformation, secondly recrystallization and thirdly alpha(2) precipitation. It is shown that recrystallization refines the microstructure. The resulting microstructure is constituted by gamma grains of mean size about 1.7 mu m, with four variants of fine acicular alpha(2) precipitates inside the grains and very small alpha(2) globular precipitates at grain boundaries. The possibilities to apply this heating for refining the microstructure in the powder metallurgy route are discussed.