Research On Hot Forging Process And Simulation Of Ti55531 Alloy Torsion Arm

Ti55531 alloy is a new type of high strength and high toughness near-? titanium alloy.Compared with the near-? titanium alloy Ti1023,Ti55531 alloy will not produce obvious composition segregation.In addition,Ti55531 alloy has wide processing range and good hardenability.Based on the above characteristics,Ti55531 alloy is suitable for manufacturing loadbearing die forgings for aircraft.Aircraft landing gear torsion arm is one of the important parts of the aircraft,which transfers the torque from the outer cylinder to the piston.Due to the complex shape of the torsion arm and the sophisticated deformation mechanism of Ti55531 alloy,it is difficult to control the material deformation and microstructure.Therefore,it is necessary to study the characteristics of hot deformation behavior and microstructure evolution mechanism of Ti55531 alloy and to establish the mathematical model of Ti55531 alloy.Furthermore,the hot forging process of Ti55531 alloy torsion arm for aircraft was studied by combining finite element with orthogonal test.This research is of great significance to improve the forming quality and performance of the torsion arm and to ensure the safety and stability of the aircraft.Besides,it also can provide theoretical guidance and reference for manufacturing,microstructure control and forging process optimization of aviation die forgings.The main research contents are as follows:(1)The relationship between the hot deformation performance parameters of Ti55531 alloy under different deformation conditions was obtained by linear fitting the experimental data,and the high temperature deformation constitutive equation of Ti55531 alloy was established.The accuracy of the constitutive equation was verified by comparing the calculated value with the experimental value and introducing the correlation coefficient and the average relative error to quantitative analysis.Furthermore,the dynamic recrystallization model of Ti55531 alloy were regressed and analyzed by the hot compression experimental results.To validate the model,the finite element simulation was performed in the hot compression tests,the simulation results are in good agreement with the experimental results.(2)Forging formability analysis was carried out on the shape and structural characteristics of Ti55531 alloy torsion arm,and the forming process of “two pieces in one module” was preliminarily designed.Based on the material model of Ti55531 alloy,the finite element model was established to simulate the forming process.Aiming at the problems in the simulation results,the forming process of “blank making + pre-forging + final forging” was further designed,and the feasibility and rationality of the process were verified by finite element simulation.(3)The effects of forging process parameters on the standard deviation of average grain size and forming load were studied and analyzed by orthogonal test and finite element simulation.The optimum forging parameters,forging temperature 820 °C,forging speed 25 mm/s,die temperature 350 °C,were obtained by range analysis and variance analysis.The standard deviation of average grain size 0.110 ?m and the maximum forming load 1690 t were obtained by the combination of the optimum forging parameters.Compared with 16 orthogonal test schemes,this scheme is the best one.