Crystal Plasticity Finite Element Simulation And Experimental Research On Thread Rolling Forming

In the process of plastic deformation of materials,the appearance of texture will have an important impact on the microstructure and mechanical properties of the material.The study of microscopic plastic deformation behaviors such as grain orientation change and dislocation slip is of great significance to reveal the law of material macroscopic deformation.The crystal plasticity finite element simulation method(CPFEM),as a tool to study the microscopic changes of materials,has become a hot spot in related research fields in recent years.In this article,pure aluminum 1060 was used as the research object,and the smooth model and rough model of polycrystalline were established based on the Voronoi method.In the process of deformation,the microscopic changes of the material of the round rod-shaped workpiece formed by thread rolling were studied.Thread rolling forming process technology was experimentally verified.Firstly,a tensile experiment was carried out at room temperature.The material performance parameters were obtained by means of simulated tensile stress-strain curve approaching the experiment.The crystal plasticity finite element method was used to study the simple loading behavior of uniaxial tension,compression,and rolling,and to analyze the inhomogeneity of material plastic deformation and the stress concentration phenomenon at the grain boundary.The simulation process was verified through experiments.The results showed that CPFEM can predict the texture evolution of the material under different forming conditions.Secondly,the thread rolling equipment was researched,and the kinematic formula in the actual thread rolling and forming process was given.The crystal plasticity finite element simulation of thread rolling forming was carried out,and the displacement field was analyzed to study the fluidity of the metal and the cause of the concave center at the workpiece end.By studying the axial and radial force state of the workpiece to explain the reason why the thread rolling forming process prevents the material from necking or even breaking.By analyzing the stress and strain of a single grain during thread rolling forming to study the periodic and complex force behavior.The averaging method was used to obtain a representative element strain curve that can more truly reflect the deformation behavior of the entire material.The shear strain rate curve was drawn to study the activation and movement of the slip system.The influence of the initial orientation and position of the grains on the evolution of the slip system was analyzed.The orientation change of a single grain was also studied,and the orientation pole points were dispersed after deformation.Due to the coordinated deformation among the grains,the orientation after torsion and rotation deformation was distributed in a flaky shape near the initial orientation.Finally,by analyzing of the experimental data of the EBSD test,the experimental pole figure was in good agreement with the crystal plasticity simulation.The accuracy of CPFEM to predict the texture was again verified.The data shows that the thread rolling forming is more uniform than ordinary rolling,and the material properties were more stable.