Effect Of Heat Treatment Temperature On Dynamic Mechanical Properties And Microstructure Of TC4 Titanium Alloy

Titanium alloy has the advantages of low density,good impact toughness,strong corrosion resistance and good thermal stability,and is often used in the fields of aeroengine compressor blades and aircraft structural parts.In the service process,TC4 titanium alloy components often bear impact loads,and there is a risk of plastic deformation at high strain rate.Therefore,it is of great significance to obtain the dynamic mechanical properties of materials and determine the influence of heat treatment temperature on the dynamic mechanical properties for optimizing the mechanical properties of materials and ensuring the service safety of components.In this paper,TC4 titanium alloy was taken as the research object,and five two-phase temperatures(850℃,900℃,920℃,960℃ and 1000℃)were selected to heat and hold the samples,and then three groups of heat-treated samples were obtained by air cooling,furnace cooling and water cooling.The Hopkinson bar experiment was used to carry out dynamic mechanical properties experiments at high strain rate.The effects of heat treatment temperature on mechanical properties and microstructure of TC4 titanium alloy were studied by means of scanning electron microscopy(SEM),X-ray diffraction(XRD)and electron backscattering diffraction(EBSD),and the relationship between microstructure and mechanical properties of TC4 titanium alloy was clarified.The results show that the material has strain rate strengthening effect under dynamic tension and compression.The dynamic tensile test shows that the fracture elongation of the three groups of heat-treated samples increases first and then decreases with the increase of the temperature in the two-phase region.The metastable β phase appeared in the microstructure of the two-phase zone treated at low temperature(850℃),and martensitic transformation occurred after loading,which resulted in the increase of fracture elongation of the material.The fracture elongation of the water-cooled material was the highest.Two phase region of high temperature(900℃-1000℃)processing,material organization by shaft primary alpha martensite of alpha’ phase content increased,leading to fracture elongation of materials continues to decline,but the yield strength,tensile strength and hardness is significantly increased.In addition,there are regular shear lip region and fiber region at the fracture of the material,and the fracture is plastic fracture.As the heat treatment temperature increases,the number,size and distribution of dimples at the fracture are reduced.Dynamic compression experiments found that the compression resistance of the samples after aging treatment is best,the rise of yield strength with temperature declining,material hardness increased with the content of alpha ’ phase in the microstructure significantly increases,In addition,shear fracture occurred in the material treated at 960℃ to 450℃,and the fracture showed fine fish-scale morphology.The conclusions of this paper can provide a basis for the optimization of mechanical properties of TC4 titanium alloy material components,and promote the application of this material component in many fields.Figure [45] Table [3] Parameter [86]...