Influence Of Cyclic Fluctuation Load On Microstructure Evolution And Mechanical Properties Of TA1 Pure Titanium Plate

Titanium and its alloys have the advantages of high specific strength,good biocompatibility,good heat resistance and corrosion resistance,and have been widely used in aerospace,medical and automotive fields.However,since pure titanium is an α phase with a close-packed hexagonal crystal structure,and there are few independent slip systems,the deformation resistance during deformation is large,and the rolling process leads to the formation of strong texture in pure titanium.Preferred orientation of particles.Based on this,this paper adopts the corrugated roll rolling process to study the titanium plate by scanning electron microscopy(SEM)and electron backscatter diffraction(EBSD),and explores the microstructure of pure titanium under periodic load during corrugated roll rolling.and texture evolution.In addition,samples were taken along the RD and TD directions of the titanium plate for room temperature tensile tests to explore the mechanical properties corresponding to different processes and different microstructures.The main experimental contents and results are as follows:(1)A three-dimensional finite element model of corrugated roll rolling of titanium plate was established using Abaqus finite element simulation software,and the reliability of the model was verified.The plastic deformation behavior of corrugated rolling and the difference between corrugated rolling and flat rolling at different rolling temperatures(400 °C,500 °C,600 °C,700 °C,and 800 °C)were investigated.In addition,when the rolling temperature is700 °C,the difference of unilateral corrugated roll rolling with different reduction ratios(15%,25% and 35%)is analyzed.The final rolling temperature is 400°C and 700°C and the rolling reduction ratio is 25%.(2)Combined with the simulation results,the rolling process of unilateral corrugated roll rolling + flat rolling is used,denoted as CFR,the rolling temperature is 400 °C and 700 °C,the reduction rate is 25%,and annealing at 650 °C for 1 h.It is found that the degree of deformation of the corrugated surface of the pure titanium plate after rolling by the corrugated roller varies greatly,specifically,wave trough> wave waist> wave crest.After the second pass flat rolling,the grains of the CFR titanium plate are smaller than that of the FFR titanium plate.At a rolling temperature of 700 °C,the texture strength of the CFR titanium plate is obviously weaker than that of the two-pass flat-rolled titanium plate,especially at the trough position.However,when the rolling temperature is 400 °C,the texture of the as-rolled state is not weakened,while the texture of the annealed state is weaker than that of the two-pass flat rolling process.(3)The rolling process of double-sided corrugated roll rolling + flat rolling is used,denoted as DCFR,the rolling temperature is 400 °C and 700 °C,the reduction rate is 25%,and the annealing treatment is carried out at 650 °C for 1h.The upper and lower surfaces of the titanium plate in this process are corrugated surfaces,and the entire titanium plate is subjected to the action of cyclic fluctuation loads.After one double corrugated roller rolling,the upper and lower surfaces of the titanium plate are wavy,and the strain size of the upper surface is similar to that of CFR.Compared with the two-pass flat rolling,the rolling texture of DCFR titanium sheet is weakened at 700 °C,while the recrystallized texture of DCFR titanium sheet is weakened at 400 °C.(4)In terms of mechanical properties,it is found that the yield strength in the RD direction of the unilateral corrugated roll rolling(CFR)titanium plate is smaller than that in the TD direction.When the rolling temperature is 700 °C,its plasticity shows isotropy,which is opposite to the rolling temperature of 400 °C,and the elongation at break of CFR titanium plate is different in the RD and TD directions,showing anisotropy.Compared with flat rolling at different rolling temperatures,the double corrugated roll rolling process(DCFR)has a small difference in strength.out isotropic.In general,the mechanical properties of the unilateral corrugated roll(CFR)titanium sheet are better than those of the double-sided corrugated roll.This study shows that the corrugated roll rolling process can weaken the rolling texture and recrystallized texture of pure titanium under certain conditions.In addition,under different conditions,the mechanical properties of corrugated roll-rolled titanium sheets can show anisotropy and isotropy,which provides a solid foundation for the application of titanium and titanium alloys in different occasions.