Abstract: In order to release residual stress and improve dimensional precision of aluminum cone-shaped part, the influence of thermal-cooling cycle on both quenching-induced residual stress and machining-induced distortion, based on numerical modeling and test analysis, is studied. The experimental results show that the distributing trend, which is compressive stress on the surface and is tension stress on the interior, of residual stresses with thermal-cooling cycle is similar to that with T6 treatment, but the amplitude of residual stress treated by thermal-cooling cycle is reduced sharply, and that the fluctuation quantity of roundness is 0.06～0.10 mm with T6 treatment, and is controlled generally within 0.04 mm with thermal-cooling cycle, the dimensional stability is improved obviously after thermal-cooling cycle. The characterization model of both quenching-induced residual stress and strain is established, the microcosmic thermodynamic behavior and fluctuating mechanism of both residual stresses and strain is analyzed. The characterization model of influence of thermal-cooling cycle on both residual stress and strain is established, the reason of releasing residual stress and improving dimensional stability with thermal-cooling cycle is that the asymmetric thermal expansion and contraction of microscopic structure is produced, the asymmetric thermal microplastic deformation is induced, and the movable dislocation is consumed and the pinned dislocation tangle and dislocation multiplication is excitated on the basis of TEM microscopic structure analysis.

Key words: Aluminum alloys, Nonlinear distortion, Quenching, Residual stresses, Thermal-cooling cycle