Study On Influenceing Factors Of Mechanical Properties Of TA15 Titanium Alloy And Improvement Of Its Performance

With the deepening of the exploration of space,the requirements for space vehicles are getting higher and higher.The general development trend of aerospace structural materials is light weight,high strength,high modulus,high temperature resistance and low cost.Titanium alloy has become a kind of important aerospace material because of its low density,high strength,high temperature resistance and corrosion resistance.How to improve the comprehensive properties of titanium alloys has become the top priority in the research of titanium alloys.The research object of this paper is the TA15 titanium alloy for aviation.This paper studied the influence of alloy hot deformation behavior and processing parameters on Microstructure and properties.through experiment,The hot forming process window of TA15 titanium alloy has been proved,which can make it get good performance in hot working process.At the same time we explore the effective method to improve the mechanical properties of TA15 titanium alloy.The main results are as follows:In the study found that,TA15 titanium alloy has obvious work hardening and dynamic softening at high temperature deformation.TA15 titanium alloy has obvious work hardening and dynamic softening at high temperature deformation.Under the condition of low temperature(below 900℃),the true stress true strain curve has obvious softening trend,which is a dynamic recrystallization curve.At high temperature,the true stress-strain curve is in the form of response curve.Based on the hyperbolic sine function of Arrhenius equation,the constitutive equation considering strain is established.The equation after friction and temperature correction can be used to predict the stress-strain relationship of TA15 titanium alloy in the two-phase region.Based on the dynamic material model,we establish the hot working drawing,and determine the safe and unstable zone of TA15 alloy during high temperature deformation.The thermal deformation mechanism of the alloy in the(alpha + beta)phase region is the dynamic recovery and dynamic recrystallization of the alpha and beta phases;The instability zone is mainly concentrated in low temperature and high strain rateregion.The main cause of instability is the local plastic flow caused by deformation heat.At the same time,We systematically analyze the relationship between the deformation parameters and the state of the phase(After deformation and heat treatment).The results show that the tensile strength at room temperture will increases with the increase of the equiaxed alpha phase content and the decrease of the Equiaxed alpha phase size and the thickness of the secondary lamellae;at the same time,the tensile strength at 500℃ will decrease with the increase of the equiaxed alpha phase content,Equiaxed alpha phase size and the thickness of the secondary lamellae.It is clear that the microstructure refinement can effectively improve the mechanical properties of the alloy,and the quantitative relationship between Technological method,microstructure and mechanical properties was established.At last,The alloy with fine grain structure was obtained by quenching of single phase zone and High temperature deformation,which significantly improves the mechanical properties of the alloy.