| 7075 as-cast aluminum alloy thin-walled tubes have been widely used in aerospace and aerospace because of their light quality,high strength,low density and other characteristics.The thin-walled tubes,which are first cast into billets and then turned into required wall thickness,can overcome the shortcomings of traditional processing methods,such as high cost,long cycle time and low material utilization,which has become the main process for thin-walled tubes.However,the forming process is a multi field,multi-factor coupling complex physical process,especially the billet as the casting state,resulting in the formation of plastic deformation and microstructure evolution process.The final organization shape determines the comprehensive performance of the product to a great extent,which directly affects the forming quality of the rotating parts.Therefore,this method of experiment and finite element simulation combining,to 7075 as-cast aluminum alloy cylindrical macro deformation behavior of multi-step hot power backward spinning process and microstructure evolution of system analysis and research,the main research contents and results are as follows:Based on the multi-pass high temperature loading test on the Gleeble-3500 type thermal simulation compressor,the deformation behavior of the 7075 as-cast aluminum alloy at high temperature was analyzed systematically.Furthermore,based on the quantitative metallographic analysis,the microstructure evolution of the alloy in multi-pass high temperature loading is analyzed.The behavior evolution mechanism and microstructure of the alloy at high temperature results obtained by fitting the deformation based on the regression analysis,we build a unified 7075 as-cast aluminum alloy macro micro coupled constitutive model,and the model correlation and error analysis,verify the reliability of the model.The shear stress strain updated integral algorithm with radial return,fortran language based on the platform,developed a unified multi-pass hot power form of counter rotating macro micro coupled constitutive model for 7075 as-cast aluminum alloy subroutine cast thin-walled tube,then the program through the VUMAT interface into the ABAQUS,simulation in order to achieve the macroscopic thermodynamic behavior and microstructure evolution.The reliability of the model and the subroutine is verified by simple loading and complex loading methods.Finite element verification of the reliable macro microcosmic coupling model based on the systematic analysis of the 7075 as-cast aluminum alloy thin-walled tube microstructure hot power backward spinning process of the evolution of the research shows that: from the general trend of the primary recrystallization fraction and average grain size distribution is not uniform and has a shaft symmetrical features.Compared to the tube ends,stable distribution is uniform;With the increase of the pass,there is an increasing trend.The stable area has maximum recrystallization fraction and average grain size,and the smallest one is the unspinning area has a decreasing trend.The recrystallization fraction and the average grain size of the tubes show an uneven trend.The distribution along the axial,circumferential and radial directions of the tubes is uneven and the fluctuation is more obvious.In the end zone and unformed zone is not conducive to the occurrence of dynamic recrystallization,the average grain size is relatively large;in the stable region of recrystallization occurs more fully,the average grain size is smaller,the fine grain zone is mainly located in the stable region;with the increase of spinning pass,multi zone and fine grained region by the outer tube transfer to the inner layer and gradually tends to be the same. |
