Study On High-efficiency Superplastic Forming Technology Of Complex Components In TC21 Titanium Alloy

TC21 titanium alloy is a new type of damage tolerance titanium alloy used in modern aerospace. TC21 titanium alloy left thrust pin in this study is one of load-bearing structure of aircraft, but it has complex shape, material utilization is low in ordinary forging process and organizational performance can not meet demand. And how can we completely and efficiently get the forming damage tolerance titanium alloy complex components has become an urgent problem. High-efficiency superplastic forming technology compared to the conventional ordinary die forging technology not only can meet the complex requirements of the component shapes of product, but also can effectively improve the efficiency of high-efficiency superplastic forming. This new method can significantly increase the productivity of the complex components of titanium alloy superplastic forming, and shows the broad market prospect in the field of engineering application of aerospace complex components in high-efficiency superplastic forming.In this paper, a series of microstructure and superplastic mechanical properties of supplier stated TC21 titanium alloy were examined. Based on the experimental results,the paper constructed TC21 titanium alloy superplastic constitutive equations,carried out superplastic tensile and superplastic isothermal forging simulation by finite element software Deform simulation, and got the best deformation parameters. Specific studies were as follows:(1)The metallurgical microstructure and elements spectrum obtained ingredients were examined by means optical microscopy and scanning electron microscopy, and got its β transition temperature of 965 ℃ by calculation.(2)The maximum m method, the efficient method based on m and robin strain rate method’s tensile tests of TC21 titanium alloy under the temperature ranged from 860℃to 940℃ were examined by electronic tensile testing machine. The experimental results showed that: the elongation and deformation efficiency of the maximum m method were431.49% and 2.48 under temperature of 900℃; the elongation and deformation efficiency of the efficient method based on m were 293.87% and 15.15 under temperature of 900℃, and the deformation efficiency improved 6.1 times compared to the deformation efficiency of the efficient method based on m.(3)The study carried out five robin strain rate method ’ s tensile tests under the temperature ranged from 860℃ to 940℃, used stepwise regression method to construct TC21 titanium alloy superplastic constitutive equations based on the Arrhenius, and calculated activation energy for 233.712kJ/mol. After the software through 1stOpt corrected regression constitutive model, the Similarity of calculated and experimental values was up to 0.99.The constitutive equation not only can accurately reflect the relationship between the material flow stress and strain, strain rate and temperature, but also as a finite element simulation conditions.(4)The superplastic isothermal forging and die were designed, the finite element model was setted into Deform-3D, then the forging forming process of left thrust pin were simulated by setting different parameters of the simulation, the simulation of different process parameters and forging methods to analyze the process of forging, and got the impact of changes in the process of obtaining the metal flow, stress-strain curve of load changes, and other parameters. Blank and mold optimization based on simulation results to determine the best method of forming and provide a strong basic of actual forging process and die design of TC21 titanium alloy.