Study On Thermal Deformation Behavior And Microstructure Of TA1 Prepared By EB Furnace Smelting Residual Titanium

Industrial pure titanium TA1 has good workability,formability,weldability and corrosion resistance.At the same time,it is not sensitive to heat treatment.It is widel y used in petroleum,chemical,aerospace,and marine fields.In recent years,the amount of titanium used in China has been increasing year by year,but due to the difficulty of extracting,smelting and processing titanium,the yield of the titanium production process is low,and the loss of tangible materials in the production process from sponge titanium to finished titanium accounts for about the total amount of feed 50% of the titanium production and processing process produces a large amount of titanium scraps,edge wires,ingot heads,ingot tails,hot-rolled plate heads,outer plates,hot-rolled scraps and other waste residual titanium,which is not only a great resource for titanium Waste and cause serious environmental pollution.Based on the above reasons,this article firstly detects the oxygen content of the titanium chips obtained after milling the pure titanium TA1 ingots,and then uses the electron beam cooling bed furnace(EB furnace)for recovery and remelting,and samples the cast TA1 ingots for use.The Gleeble-1500 thermal simulation testing machine performed single-pass and multi-pass cooling and thermal compression experiments to study the thermal deformation behavior and microstructure evolution of the TA1 ingot under different deformation temperatures and deformation conditions,and the following conclusions were obtained:Tungsten argon gas protection button furnace was used to detect the oxygen content of TA1 titanium scraps,which was 0.08%.After smelting the titanium scraps with an electron beam cooling bed furnace,due to gas seepage in the electron beam cooling bed furnace during the production process,the internal The oxygen content increases,and the resulting TA1 ingot oxygen content increases to 0.11%.The sample is subjected to a single-pass thermal compression under the conditions of temperature of 860℃,890℃,920℃ and K-890℃(Supercooled β phase region),deformation 10%-60%,and strain rate 10/s.The stress gradually decreases with the increase of deformation temperature.When the deformation temperature is K-890℃ and different deformation amounts,the flow stress is close to the flow stress at 920℃ but much smaller than the flow stress at 860℃ and 890℃.During thermal deformation,the grains with the same overall phase are squashed and elongated,but the grains with different phases rotate in a direction at a certain angle to the deformation direction under the action of compressive stress.The angle gradually decreases as the deformation continues,and finally the grains with the same overall phase are squashed and elongated.Because the grains of different phases are mutually squeezed,stress concentration is caused and the energy at the grain boundary increases.Dynamic recovery and dynamic recrystallization occur between the crystal grains.After the sample has undergone multiple cooling and thermal compression experiments,the peak flow stress increases with the increase of the number of passes.The higher the temperature,the smaller the corresponding peak stress.When the deformation temperature is K-890℃,since the transformation from β phase to α phase is carried out under the dual effects of supercooling and deformation,the driving force of the transformation and the nucleation rate are increased,and the flow stress curve is due to dynamic softening.It is equivalent to the flow stress at 920°C.As the deformation temperature increases and the amount of deformation increases,the deformed lamellar structure gradually becomes spheroidized,and the grain size gradually decreases and becomes more uniform.At the same time,the small-angle grain boundary gradually transforms into the large-angle grain boundary.The crystallization rate increases,and the texture strength and direction change.However,compared with the recrystallization rate of TA1 ingot when the deformation rate is small,the strain rate(10/s)in this experiment is larger,the recrystallization incubation time is shortened,and the driving force is small.When the deformation temperature is860℃,890℃ and 920℃,the recrystallization rate is 0.15%,0.22%,0.61%respectively.When the deformation temperature is K-890℃,the recrystallization rate increases to 0.5%,and the degree of recrystallization is small.