Study On Dynamic Mechanical Properties Of Titanium Alloy Dynamic Thermal Oxidation

At present, titanium alloys are widely used in aerospace, chemical industry, sports equipment and bio medical field because of its high specific strength, corrosion resistance and biocompatibility. Titanium alloy has low hardness and high friction coefficient, and the surface mechanical properties are obviously less than the common base metal structure material, which limits its application range, and affects the safety and reliability of the structure. Therefore, modifying the surface of titanium alloy to improve the surface load resistance is a key problem to be solved in the application of titanium alloy.Based on the solid solution of oxygen in titanium alloy can play a significant strengthening effect and thermal oxidation treatment diffusion layer(titania and alumina oxide layer occurs on the surface of titanium alloy), formed by oxidation of titanium oxide,high hardness, adhesion characteristics such as to improve titanium alloy, wear resistance,obvious effect, thermal oxidation treatment not only decreases the coefficient of friction of the material surface, and the amount of wear and untreated materials decreased by two orders of magnitude. In order to further optimize the tribological properties of the surface treated titanium alloy and to understand the Tribological Mechanism, it is important to quantitatively investigate the parameters of the elastic and plastic properties of the titanium alloy after oxidation treatment.Based on the above problems, in this paper, the mechanical performance of thermally oxidized titanium alloy TC4 were systematic research. The main work and results are as follows:1) Under different conditions by electronic universal material testing machine and Split Hopkinson Pressure Bar(SHPB) on thermally oxidized titanium alloy TC4 were quasi static and dynamic tests, based on thermally oxidized titanium alloy TC4 dynamic constitutive relation of the above experimental data and Johnson cook model fitting was obtained.2) The dynamic constitutive relation of Johnson-Cook for TC4 titanium alloy was obtained through the numerical simulation of bullet impact effect on TC4 titanium alloy, and then a comparative analysis is made of the mechanical response of the hemispherical shellconsidering the strain rate effect of the material and the strain rate effect of the material which mainly studied the peak value of contact force and the mechanical index of peak displacement.The result shows that the effect of strain rate on the mechanical properties of the spherical shell under shock loading has a significant effect on the mechanical properties of the material,and the further evidence of TC4 thermal strain titanium alloy material itself has a very important significance rate effect.