High Temperature Dynamic Mechanical Properties Of Ti-5553 And Its Chemical Performance Match With Tool Materials

Titanium alloy Ti-5553 is a new type of metastable beta titanium alloy.It has many features,such as high strength,low segregation of sensitivity,good hardenability,good toughness and low elastic modulus.Ti-5553 has a poor machinability because of its high strength,high toughness and high chemical activity.It shows high cutting resistance,high cutting temperature,bonding with tools,and a heavy chemical wear of cutting tool materials.This paper bases on the properties of Ti-5553 materials,aims to study the high-temperature dynamic mechanical properties,for the constitutive model of Ti-5553 was built.To discuss the chemical property matchingbetween two aspects of Ti-5553 and tool materials,their oxidation and diffusion behaviorswere studied.The relationship between adiabatic shear of serrated chip and dynamic mechanical properties in high temperature was studied through cutting experiments to the Ti-5553.The oxidation and diffusion of tools were investigated.The mechanical properties of the material under quasi-static compression are analyzed by the real stress-strain curve of the quasi-static compression test of Ti-5553.The stress-strain curves at different strain rates and temperatures obtained from the Hopkinson pressure bar test of Ti-5553 were used to analyze the strain rate hardening effect and thermal softening effect.Based on the results of quasi-static compression test and Hopkinson pressure bar test,Johnson-Cook constitutive model of Ti-5553 was established based on the regression analysis.What's more,the model was verified.The oxidation products of Ti-5553,uncoated cemented carbide,coated cemented carbide and PCBN composite were analyzed by XRD at differenttemperatures.The surface properties of them were measured by SEM,too.Under the oxidation reaction,the changes of the surface morphology of the material on the macro and micro scales were observed by light microscopy and scanning electron microscopy respectively.The mass per unit area before and after the oxidation was recorded,and the change trend of the surface hardness before and after the oxidation was measured.With all the five aspects the oxidation behavior between Ti-5553 and tool materials was studied.Ti-5553 was firmly fixed to three kinds of tool materials,including uncoated cemented carbide,coated cemented carbide and PCBN composite tool respectively,and then placed in a high-temperature resistance furnace for quantitative heat preservation and heat treatment.The diffusion behavior between Ti5553 and the tool material was analyzed.Scanning electron microscopy EDS was used to scan the cross section of the contact surface between Ti5553 and the tool material,and to analyze the interdiffusion of related elements in the material at different temperaturesTi-5553 alloy was cut with uncoated cemented carbide,coated carbide and PCBN tools.Based on the analysis of the change of chip morphology and the Johnson-Cook constitutive model of Ti-5553,the adiabatic shearing of serrated chip was verified.The energy spectrum analysis on the surface of different material tools was carried out through a long time cutting experiments.The distribution of oxidation and diffusion degree of three kinds of materialwas analyzedon thefiont and flank surfaces.