Research on quenching residual stress and residual stress reduction process of large-scale 7085 aluminum alloy cylindrical parts
Taking large-scale 7085 aluminum alloy cylindrical parts as the research object,the method of ensuring the performance of large-scale aluminum alloy forgings to the maximum extent and reducing the residual quenching stress as much as possible was studied.Fi-nite element models for quenching and subsequent cold expansion were established based on the Abaqus platform,considering the data in-heritance relationship between the quenching and cold expansion processes.The effect laws influence of process parameters on perform-ance of forgings and residual stress were analyzed.For the quenching process of large-scale 7085 aluminum alloy cylindrical parts,the time-temperature-transformation(TTT)curve and time-temperature-property(TTP)curve of 7085 aluminum alloy were integrated into the Abaqus user subroutine USDFLD,and the precipitation phase content and distribution,corresponding hardness changes and residual stress distribution under different quenching conditions were calculated.A quenching water temperature of 35 ℃ was determined as the optimal choice.In the cold expansion process for reducing residual quenching stress,orthogonal simulation experiments were conducted under different quenching water temperature conditions regarding expansion amount,expansion pass and rotation angle between each pass.The results show that the expansion amount has the most significant effect on reducing residual stress,with an expansion amount of 4.5％resulting in the best strain uniformity and most thorough reduction of residual stress for large-scale 7085 aluminum alloy cylindrical parts.The optimized quenching process and expansion scheme obtained through simulation were applied to production trials,and the mechanical properties of the large-scale cylindrical parts meet the design requirements.The measured results of residual stresses show good consisten-cy with the simulation results.
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