Research On Processing Technology Of TC4 Bar And Profile

TC4 titanium alloy is commonly used in aircraft truss and secondary load-bearing frame because of its excellent high-temperature mechanical properties.At present,TC4 titanium alloy bars are usually produced by extrusion,but there are some problems in the actual production process,such as unstable extrusion lubrication effect and unclear process parameters,which seriously affect the promotion and application of TC4 extruded bars.TC4 profile is an important part of material for a key aircraft in AVIC aviation industry.Due to the immature technology and unstable quality of TC4 profile produced by our country,our country relies on imports for a long time.In order to break this passive situation,the extrusion technology of TC4 bar and TC4 profile was studied.In order to determine the technological parameters of TC4 bar extrusion,this paper first study the influence of extrusion lubricant on the surface quality of TC4 bar,then study the influence of extrusion temperature,annealing temperature and hot straightening parameters on TC4 bar,and determines the best technological parameters of TC4 bar extrusion.With reference to the technological parameters of TC4 bar,the technological parameters of TC4 bar are explored and studied The results are as follows:(1)The Al content of the TC4 alloy was 6.2%?6.5%,the V content was 4.0%?4.3%,the Fe content was 0.03%?0.05%,the C content was 0.1%,the N element was 0.01%?0.02%,the O element was 0.13%?0.15%,and the phase transition was between 980?1000?.Therefore,the selection of production route and production technology is reasonable,can meet the performance requirements of TC4 test ingot.(2)TC4,which adopts the lubrication mode of copper sheath,squeezes the billet,and its surface coating is not uniform,while the extrusion coating effect is good by the lubrication mode of glass powder.The tensile strength of TC4 bar decreases from 720 MPa to 672 MPa by increasing the extrusion temperature from 800? to 900?.As the extrusion temperature rises from 800? to 900?,the alpha and beta tissues in TC4 bar gradually increase.The high-temperature tensile strength of TC4 bar decreases from 682 MPa to 645 MPa by the annealing temperature rising from 700? to 900?.The TC4 bar was straightened by air cooling and oil cooling respectively within the range of 700?740?,and there was no obvious difference between the two technological methods.(3)The use of glass powder lubrication method can effectively meet the effect of TC4 profile extrusion billet surface,the glass powder completely immersed in the TC4 profile surface,no abnormal surface was found.With the extrusion temperature rising from 800? to 900?,the high-temperature tensile strength of TC4 profile decreased from 768 MPa to 405 MPa,the error of high-temperature tensile strength decreased from 18 MPa to 24 MPa,the high-temperature elongation rate of TC4 profile increased from 37% to 44%,and the error of elongation rate decreased from 6% to 5%.With the extrusion temperature rising from 800? to 900?,the rheological morphology of the alpha in TC4 profile still remains after extrusion,and the alpha structure gradually becomes larger as the extrusion temperature increases.With the annealing temperature rising from 700? to 900?,the high temperature tensile strength of TC4 profile decreases from 720 MPa to 670 MPa,and the high temperature elongation increases from 51% to 60%.In addition,with the increase of annealing temperature,the error of high temperature tensile strength decreases from 25% to 12%,and the error of elongation decreases from 7% to 4%.The TC4 bar was straightened by air cooling and oil cooling respectively within the range of 700?740?,and there was no obvious difference between the two technological methods.(3)The TC4 profile products are produced with extrusion speed of 90 mm/s+ extrusion temperature of 980?+ straightening temperature of 750?+ annealing temperature of 800?.The surface quality is qualified and the mechanical properties meet the technical requirements,which can meet the requirements of industrial batch production.