Constitutive Model And Numerical Simulation Of Semisolid Forming Of Aluminum Alloy Powder

Semi-solid powders forming technology is a promising near net forming technology,which not only has the high-quality characteristics of liquid and solid metal forming,but also contains the advantages of powder metallurgy.The semi-solid metal powders forming technology breaks the traditional dendritic solidification method,and the finished material prepared by this technology has the obvious advantages of small grain size,uniform size,small deformation resistance and short forming process.At present,the research on the transform mechanism of semi-solid powders is relatively mature,but the research on establishing a constitutive model in line with the actual change process of materials and applying it to numerical simulation technology is still in the explosive stage,some important influencing factors are not taken into account,and this part of research is the premise of numerical simulation of semi-solid metal forming.In this paper,the thixotropic rolling of aluminum alloy powders is taken as the research object.The influence of the main factors such as initial relative density,temperature,strain rate and solid-liquid fraction on the thixotropic rolling of aluminum alloy powders is studied in detail by the method of combining experimental and numerical simulation technology.It provides reference value for further study of semi-solid forming technology,and also lays a certain foundation for the development and application of semi-solid near-net forming technology.In this paper,2024 aluminum alloy powder was used as the research material.The method of material numerical simulation and experiment was adopted to determine the optimal composition of the material and investigate the material semi-solid forming process window and thixotropic forming characteristics.The thixotropic forming constitutive model of 2024 aluminum alloy powder with liquid fraction between 30% and 60% was established based on the stress-strain data from the semi-solid compression tests at different temperatures,initial relative densities and strain rates and three kinds of Arrhenius types equations of Zener-Hollomon parameters.It provides a theoretical basis for optimizing semi-solid powder forming process and mathematical model for numerical simulation of semi-solid powder forming.The constitutive model was embedded into Deform-3D software with the help of Fortran programming language.The accuracy of the constitutive model embedded into the software was verified by comparing the numerical simulation results of uniaxial hot compression with the experimental results.The finite element numerical simulation technology of Deform-3D software embedded with the constitutive model and the solidification and melting simulation technology of Fluent were used to study the influence of the main factors on rolling strip and explore the solidification mechanism of the slurry in the rolling process in a certain range of semi-solid temperatures.