Study On High Temperature Deformation Behavior And Spheroidization Process Of Lamellar Structure Of TC4 Titanium Alloy Manufactured By Additive

TC4 titanium alloy is(α+β)Two phase titanium alloy has good comprehensive properties and medium strength.It is one of the most widely used titanium alloys in the world.In the face of forming complex parts,the disadvantages of low material utilization,long production cycle and high manufacturing cost have limited the development of titanium alloy industry.In recent years,the rapid development of various fields has improved the quality requirements of TC4 titanium alloy.Additive manufacturing technology uses high-energy density laser to melt metal powder to realize rapid prototyping.Additive manufacturing technology has higher utilization rate of materials than traditional manufacturing methods,shorter manufacturing cycle and lower cost.However,the additive manufacturing technology is manufactured by stacking the deposited layers before heating,and the metal is subjected to multiple thermal cycles.The microstructure of TC4 titanium alloy produced by additive manufacturing is in an uneven deposition state,which affects the mechanical properties of the metal,which has a certain gap with the titanium alloy produced by traditional methods.Heat treatment can refine the non-uniform deposited structure in TC4 titanium alloy and improve the mechanical properties of the alloy.In this paper,the high temperature deformation behavior of TC4 titanium alloy manufactured by additive is analyzed through thermal compression and heat treatment experiments;A dynamic recrystallization model describing the spheroidization process of TC4 titanium alloy sheet was established.The dynamic recrystallization model is transformed into FORTRAN language and programmed into the custom development program of DEFORM-3D.Through the secondary development of finite element software,the spheroidization model of TC4 titanium alloy can be verified.(1)Through the hot compression experiment of additive manufacturing TC4 titanium alloy,the stress-strain curves under different process parameters are obtained,the high-temperature deformation behavior is studied,the energy dissipation diagram and instability diagram of additive manufacturing TC4 titanium alloy are superimposed,and the hot working diagram is obtained,so as to find an excellent hot working window for additive manufacturing TC4 titanium alloy under the conditions of 973k-1173 k.(2)The effect of different deformation parameters on the transformation process from lamellar structure to equiaxed structure was analyzed.A dynamic recrystallization model describing the spheroidization process of TC4 titanium alloy sheet was established.(3)The secondary development process of finite element software DEFORM-3D is completed,so that the software can simulate the volume fraction of dynamic recrystallization equiaxed structure of the alloy.Using image processing software PS and ipp6,the volume fraction of equiaxed microstructure of TC4 titanium alloy samples made by additive under different deformation conditions was measured by area method.(4)The dynamic recrystallization spheroidization model of TC4 titanium alloy produced by additive is compiled into DEFORM-3D software by FORTRAN language.The high-temperature compression experiment process in this paper is simulated.The simulated dynamic recrystallization data is compared with the actual measured dynamic recrystallization data to verify the accuracy of the dynamic recrystallization spheroidization model.