Study On Microstructure And Properties Of TA15 Titanium Alloy Based On High-pressure Torsion

Titanium and titanium alloys are widely used in aerospace,petrochemical,and biomedical fields for their advantages of low density,good heat resistance,and high specific strength.They have become essential metals for the development of new technologies,new processes,and new equipment material.TA15 titanium alloy is a near?titanium alloy with high aluminum content.It has moderate room temperature,high temperature strength,excellent thermal stability and welding performance,and good process plasticity.It is mostly used for aircraft structural parts or engine parts.In order to make titanium alloy meet the requirements of practical application,the traditional method is to obtain the ideal microstructure state through deformation heat treatment to improve the overall performance of the titanium alloy.In recent years,due to its good operability and applicability,the large plastic deformation process has been widely used in the preparation of ultrafine grained materials and improving the mechanical properties of the material.In this paper,semi-restricted high-pressure torsional die was used to perform high-pressure torsion experiments on TA15 titanium alloy under different process parameters.Through the observation of metallographic structure and X-ray diffraction technique,the high-pressure torsional deformation characteristics of TA15 titanium alloy were analyzed,and the evolution of microstructure,substructure and deformation texture during the deformation process was deeply studied.The results show that the microstructure of TA15 titanium alloy is effectively refined after high pressure torsion,the deformation degree of the microstructure is not uniform along the radial direction and height direction.The turning number and loading pressure can promote the microstructure refinement.With the turning number increasing,the size of subcrystal decreases first and then increases,and the microcosmic increase and dislocation density are gradually increased.The size of the subcrystal gradually decreases with the increase of the loading pressure,and the micro strain and dislocation density gradually increase with the increase of the loading pressure.The TA15 titan_—ium alloy has a_—st_—rong basal texture.The main texture components are{0001}<1010>and{0001}<2110>.After high-pressure torsional deformation The preferred orientation of the material changes,and the orientation change before and after deformation is not a continuous evolution process.After high-pressure torsional deformation,the grain orientation of the material undergoes a sudden change.The microhardness and recrystallization behaviors of the TA15 titanium alloy after high-pressure torsion deformation were characterized.The results show that the microhardness of the TA15 titanium alloy after high-pressure torsion deformation is significantly increased,and the microhardness of the TA15 titanium alloy is unevenly distributed along the radial direction and the height direction.Both the turning number and the loading pressure have an effect on the microhardness.The high-pressure torsional deformation of TA15 titanium alloy is mainly enhanced by grain refinement and dislocation proliferation.After high pressure torsion deformation,the thermal stability of TA15 titanium alloy decreases slightly.