Simulation Analysis On Damage Process And Torsional Performance Improvement Of Ultra-high Strength Steel Wire Drawing Process

Ultra-high strength steel wire through the cold drawing deformation to obtain high-strength mechanical performance,it is widely used in large-span bridges and other civil engineering.When the yielding strength of the wire is improved by cold drawing,the material significantly reduced plasticity,brittle,torsional performance has greatly reduced.With the continuous improvement of production practice these years,over the years the overall mechanical performance of the wire has been greatly improved,but the torsional performance has been unsatisfactory.From the point of view of damage mechanics,this paper analyzed the damage phenomena such as microspores formation and expansion process in the process of wire processing to enhance the torsional performance of steel wire and optimize the quality of steel wire.The finite element method,damage mechanics theory,multi-scale simulation method are combined to establish the numerical model for deformation analysis of drawing process of ultra-high strength steel wire.The selection of damage evolution method is discussed with both single-scale and multi-scale method.The mechanism of damage initiation is analyzed in the drawing process,the 3D model for multi-pass drawing analysis is established,and the plastic deformation and damage evolution during dynamic process is obtained.The main work of this paper is to analyze the variation law of the internal stress of the ultra-high strength steel wire,torsional performance trends and the law of the damage evolution of the metal material during the multi-pass drawing process in the given mold vertex angle,the line diameter and pass compression ratio parameters by industrial production.The damage evaluation method is proposed,and the damage index is given to evaluate the performance of the steel wire from the view of damage in industrial production.Torsional performance trends,the relationship between the law of damage evolution and the mechanical parameters and drawing angle of the steel wire during the drawing process is analyzed.The numerical model of the drawing process of the damaged steel wire under single scale and multi-scale is established respectively.The difference of the two methods is discussed,and the numerical results are compared and analyzed.Through the multi-scale method,the process of damage evolution and stress change in the area of serious damage of steel wire is observed.In this paper,it is found that the damage of the ultra-high strength steel wire is concentrated in the area near the central axis of the wire after the multi-pass continuous drawing process;With the increase of passages,torsional performance is reduced,the damage of each node in the damaged area is increasing,and the degree of increase is closely related to the compression ratio.In the single scale model,the damage level of the damaged area in the steel wire is low after one drawing.From the second pass,the damage to the area near the axis of the wire is developing rapidly,and the damage is concentrated on the central axis.It is found that the Von Mises stress decreases first and then increases with the increase of the distance.In this paper,the influence of the parameter of the wire drawing process and the parameters of the wire material on the mechanical properties after wire drawing are discussed.The results show that under the design of the existing mold parameters and material parameters,the increase of the draw angle of the drawing,the reduction of the mean value of the strain and the improvement of the porosity will increase the damage index and reduce torsional performance after drawing.The damage index is the most sensitive to the porosity parameter,and the fluctuation degree of plastic strain is the most affected by the strain mean parameter.The numerical model of the wire drawing process was established by two methods of single scale and multi-scale,and the simulation results were analyzed.They were consistent in the total residual stress and plastic strain distribution.Due to the multi-scale approach focused on the serious development of damage areas-near the center of the wire,the results show that the maximum damage of the steel wire is no longer the central axis,but slightly deviated from the central axis,and the damage index is also improved.