High Temperature Thermal Deformation And Process Research Of Dual-phase Titanium Alloy Wire

TC4 titanium alloy is a type of??+??titanium alloy,which has high plasticity and impact toughness,and it has excellent comprehensive performance.It is often used as an important component in aviation,aerospace and other fields.Titanium alloy wire has good corrosion resistance,high specific strength,and high temperature performance.Its comprehensive performance is far superior to other metal materials such as stainless steel and aluminum alloy.It is widely used in repair welding of turbine disks and blades in aerospace engines,welding of casings,filters in the chemical industry,dental implants for human bodies implanted in the medical field,skull fixation,and various fasteners and springs,etc.Due to the poor processing performance of titanium alloy,the actual production needs to be formed at a high temperature,and the hot drawing process is used for forming the titanium alloy wire.In order to optimize the process design,it is necessary to learn the deformation behavior of the material under different deformation conditions through experiments.In this paper,the TC4 titanium alloy as the research object,through the TC4 titanium alloy hot tensile simulation test,the deformation temperature and strain rate of different thermal deformation behavior of TC4 titanium alloy,drawing flow stress curve,the establishment of the TC4 high temperature tensile The deformation constitutive equations and thermal processing maps provide theoretical guidance for optimizing the hot drawing process of TC4titanium alloy wire.According to the experimental results obtained by the hot-stretching experiment,the hot-drawing test of the TC4 titanium alloy wire rod was performed,and the influence of the drawing temperature and drawing speed on the microstructure and mechanical properties of the TC4 titanium alloy wire was explored.Thermal drawing production specifications provide a theoretical basis.The main findings are as follows:?1?In the process of hot tensile deformation of TC4 titanium alloy,the maximum deformation resistance decreases with the increase of deformation temperature at the same strain rate.When the deformation temperature remains unchanged,the maximum deformation resistance increases with the increase of strain rate.Under the deformation conditions of 800⁹60°C and 0.01¹0s^-1,the deformation activation energy of TC4titanium alloy is Q=705.87KJ/mol.Its maximum resistance constitutive equation:?=?1/0.005117?In{(Z/8.96042×10³⁰)^1/n+[(Z/8.96042×10³⁰)^2/n+1]^1/2}.The best process parameters when the strain is 0.15 is the deformation temperature of918⁹28°C,the strain rate is between 0.01⁰.0115s^-1;when the strain is 0.2,the best process parameters when the deformation temperature is 800⁸15°C,and the strain rate is 0.01⁰.0153s^-1.?2?During the drawing from?8mm to?5.2mm,the equiaxed?-tissue is very slender after being drawn and deformed,the grain aspect ratio is the largest,the tensile strength increases by 23.26%,and the elongation decreases by 15.01%.After two intermediate annealing treatments,the microstructure was iso-axially distributed and the properties were improved.The tensile strength decreased by 16.74%and 16.03%,respectively,and the elongation increased by 34.3%and 59%,respectively.When pulled to?2.0mm,the tensile strength increased by 44.1%compared to?8mm,and the plasticity also increased by 18.65%.The overall performance was optimal.?3?When the strain rate is the same,the higher the temperature is,the more recrystallization becomes.The tensile strength decreases with the increase of drawing temperature,and the plasticity increases with the drawing temperature;at the same drawing temperature,drawing When the strain rate is 0.4s^-1,the internal recrystallization of the material is sufficiently coarse and the minimum tensile strength is the highest.At the strain rates of 1.2s^-1 and 2s^-1,the recrystallization is not sufficient,the structure is finer,and the strength increases plastically.From a comprehensive consideration,the drawing temperature is 850°C,and the strain rate is 1.2s-1?the corresponding engineering strain rate is 3m/min?.The parameter is the best hot drawing process.During the hot drawing process,the grain structure inside the sample is uniform,and the crystal grains are roughly equiaxed,all elongated along the drawing direction.The orientation of the crystal grains also changed significantly.Due to the effects of the drawing force and the pressing force,the{101?0}<011?0>plate textures were formed,and the higher the drawing speed was,the higher the strain rate was.The greater the strength of the texture.?4?In one annealing experiment,with the increase of annealing temperature,the size of the microstructure grows and the distribution is relatively uniform.With the increase of the annealing temperature,the strength of the material significantly decreases and the plasticity increases.After double annealing,the number of secondary?phases precipitated inside the material increases,and the size increases.A typical equiaxed?+intergranular?structure is obtained,which reduces the annealing strength slightly,and the plasticity increases greatly;With the increase of the second annealing temperature and the second annealing temperature,the size of the primary?phase increases,and the number of precipitated secondary?phases increases,the size increases,the strength of the material decreases,and the plasticity increases.?5?After one annealing experiment,the tensile fracture after heat treatment at750°C belongs to cleavage fracture,and the quasi-cleavage fracture between cleavage cleavage and dimple fracture at 800°C and 850°C,with a rise in the temperature of a heat treatment.High,plasticity has increased significantly.In the double heat treatment process,the room temperature tensile fracture of the sample belongs to the dimple fracture,and with the increase of the double annealing temperature and the double annealing temperature,the equiaxed dimples have a tendency of becoming larger and darker.Plasticity increases with one annealing temperature and double annealing temperature.