| The shear bending forming technology of tubes is a forming process suitable for tubes with small bending radius.This method is suitable for forming materials with better plasticity under normal temperature conditions,but not suitable for forming materials with high strength or poor plasticity.In order to reduce the deformation resistance and improve the plastic deformation ability,a hot shear bending deformation method is proposed.However,the structure of the material will be changed under the coupling effect of temperature field and shear deformation.The performance of material will be affected by the structure of material.Therefore,it is necessary to study the evolution law of microstructure under the coupling of temperature field and stress field.Based on the cellular automata method,the microstructure evolution of TA18 titanium alloy during hot shear bending is systematically studied by computer simulation technology.The tube shear bending forming methods for forming small bending radius tubes are summarized,including tube mandrel shear bending forming,tube shear hydro-bending and hot shear bending forming.The advantages and limitations of the microstructure simulation methods are analyzed,and its applications in the field of material microstructure simulation are summarized.The effect of shear deformation on the microstructure and properties of titanium alloy is summarized.The true stress-strain curves of TA18 titanium alloy at different forming temperatures and strain rates are obtained by hot tensile experiments.The constitutive model of TA18 titanium alloy is established,based on the true stress-strain curves.The microstructure evolution model is established,based on the cellular automata method.The method of numerical simulation is used to study the law of shear strain and microstructure evolution in the process of hot shear bending.A numerical simulation model for hot shear bending of sheet metal is established to research the effects of different process parameters on hot shear bending of sheet metal.The law of shear strain distribution and grain evolution of hot shear bending process is revealed.An experimental device for hot shear bending of sheet is designed.The numerical simulation model of hot shear bending of TA18 titanium alloy rectangular tube was established by using the method of numerical simulation.The effect of different process parameters on forming tube is studied.The distribution law of the shear strain of the formed tube and the change law of the strain in the typical area of the hoop and axial are revealed.The effect of different process parameters on the microstructure of the tube is studied by using the microstructure simulation method.The microstructure evolution law of the typical area of the shaped tube is revealed. |
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