Study On Mechanical Behavior And Microstructure Evolution Of TA15Titanium Alloy During Hot Deform

TA15titanium alloy is high aluminum equivalent damage tolerance type titaniumalloy and one of the important structural materials in China’s aviation industry. As theTA15titanium alloy has been used increasingly in the aircraft and engines, itssemi-increasing variety (such as sheets, rods and forgings, etc.), and the manufacturingprocess also tends to diversify. There have been many new phenomena in thedevelopment process of TA15semi-finished products, and it will have great significancethat from the level of the phase transition and the microstructure to explain thesephenomena.Based on the isothermal constant strain rate compression experiment, revealstemperature, strain rate and deformation on the influence law of flow stress of TA15titanium alloy during hot deformation. It is found that flow stress of TA15alloy isaffected by deformation temperature and strain rate significantly.The microstructures of samples were observed after hot deformation. With thermaldeformation under different conditions, preferred orientation of TA15alloy internalgrains is different. The plastic deformation is going to occur in the slip systems of someslip planes by first reaching the critical resolved shear stress, which makes grains torefine and eventually lead to a change in the structure orientation. Its direction andintensity is closely related to the stress-strain state of the material, and closely relatedwith its own softening mechanism. Process for generation and disappearance of textureis dynamic continuous change. Water-cooled after hot deformation, TA15alloymartensitic transformation occurs, obtaining microscopic structure varies greatly atdifferent deformation temperature, and martensite phase and β-phase are in a metastablestate. After the900℃high temperature deformation, equiaxed structure could beobtained. When the deformation temperature reaches950℃, get a typical duplexmicrostructure, and the habit plane is (334)β. When deformation temperature exceeds1000℃, widmanstatten is obtained after water cooling, and the habit plane is (334)βand(344)β. By Quenching and aging method, TA15alloy will transform to stable α+β phase,which can effectively improve its strength and mechanical properties, and increase theservice life.Therefore, in the formulation of titanium alloy hot deformation process, you need toplan as a whole to consider factors such as deformation temperature, strain rate and deformation degree in order to select the optimum technological parameters.