Research On Continuous Rolling Process For Thin-wall Section Of TA15 Titanium Alloy

Titanium and titanium alloys have the advantages of low density,high specific strength,good thermal stability and excellent corrosion resistance,and have good matching with carbon fiber composite materials,so they have broad development prospects in aviation,aerospace and military fields.Titanium alloy thin-walled profiles are widely used in key parts such as engine compartments,fuselage compartments,tail covers and load-bearing frames.Due to the narrow processing temperature window,the forming of thin-walled titanium alloy profiles is difficult,and the size and performance are difficult to meet the requirements,and high-quality titanium alloy thin-walled profiles still rely on imports.Hot rolling has the advantages of large production scale,high production efficiency,small energy consumption and low product cost,and is an ideal processing method for batch and efficient production of thin-walled profiles.Therefore,this paper takes TA15 titanium alloy thin-walled L profile as the research object,carries out the hot working process,continuous rolling hole pattern design and continuous rolling process simulation research of TA15titanium alloy,and explores the electromagnetic induction heating supplement scheme of rolling parts in the continuous rolling process of TA15 thin-walled profile.By carrying out the isothermal constant strain rate compression test of TA15 alloy under deformation temperature of 750°C～1 050°C and strain rate 0.1 s^-1～20 s^-1,the influence of strain variable,deformation temperature and strain rate on the thermal deformation behavior of the material was analyzed,the temperature correction of the rheological curve was carried out based on the adiabatic temperature rise effect,the hot processing diagram was established and the safe hot rolling process interval was clarified.The results show that the safety interval of hot working of TA15 alloy when the strain variable is 0.2～0.6 is:deformation temperature 880°C～980°C,strain rate 0.1 s^-1～3 s^-1.Taking TA15 titanium alloy equilateral thick and thin-walled L-profile as the production goal,the hot rolling hole pattern design was carried out and the continuous rolling relationship of each pass was calculated,and the finite element model was established by DEFORM software to simulate and improve the hole pattern system,and the reliability of the finite element model was verified by carrying out single-pass hot rolling experiments.The influence of process parameters such as opening temperature and rolling speed on temperature field,stress field and damage value was systematically studied,and a reasonable hot continuous rolling process was determined:the opening temperature was950°C,and the final rolling speed was 6 rad/s.Based on this continuous rolling process,the temperature distribution,strain distribution and speed distribution of each pass of TA15titanium alloy thin-walled L profile rolling parts were analyzed.Aiming at the problem that the local temperature is too low during the continuous rolling process of TA15 titanium alloy thin-walled profiles,the optimization measures of local online induction heat supplementation are proposed.The two-dimensional induction heating finite element model was established by DEFORM-2D,and a reasonable induction heating process was determined by comparing the influence of different induction heating parameters on the heating effect:the inductor section radius was 3.5 mm,the distance between the inductor and the rolled parts was 3 mm,the current frequency was 8 k Hz,the current density was 8 A/mm²,and the induction heating time was 1.5 s.Based on this process,the finite element simulation of rolling after heating was carried out.The simulation results show that the induction heating process can effectively increase the corner temperature of TA15 thin-walled L profile.