Research On Microstructure And Mechanical Properties Of New Type High Strength And High Toughness Ti5563 Titanium Alloy

Beijing Nonferrous Metals Research Institute developed the Ti5563 alloy,which is a new type of high strength and high toughness ? titanium alloy.Ti5563 alloy has high deformation performance and weldability.Currently,the alloy is successfully used as a cold-formed thin-walled tube and related hot-through bar in the field of aviation applications.In this paper,the Ti5563 alloy hot-rolled and cold-rolled tube is the main research object.Two different heat treatment processes were used to explore the different heat treatment process on the microstructure and mechanical properties of the alloy tubes.The microstructure,macroscopic morphology and tensile property after solution and aging treatment and direct aging was analyze by OM,SEM,TEM,XRD and electronic tensile test machine.The characteristics of aging strengthening in different heating process were discussed and the best heating processing for the alloy was explored.It is found that the comprehensive performance of the alloy after the aging solution is worse than that of the direct aging,and the direct aging treatment is a more effective way to improve the comprehensive performance of Ti5563 alloy.For Ti5563 alloy heat-rolled tube after directly aging,with the aging temperature increases,a phase precipitation decreased,the size increases.For the shape of a phase,the needle continuous growth to thin stripes,short rods or even near spherical.The tensile strength decreases and plasticity increases with the temperature rise.After 600?(2h)the direct aging,Ti5563 alloy hot-rolled tube obtains the best tensile strength and plastic match,the strength is 1219MPa and elongation is 9%.The comprehensive mechanical properties of Ti5563 cold-rolled tube after solid solution aging are better than those of direct aging,and the solution aging treatment is a more effective method to improve the comprehensive performance of Ti5563 alloy cold-rolled tube.The tensile strength and plasticity of the alloy cold rolled tube are best after the aging of 740?(0.5h)+520?(8h)and 780?(0.5h)+520?(8h),the strength is about 1350MPa,and elongation is about 11%.For Ti5563 cold-rolled tube,when solution temperature at 720??780?,and aging temperature and time is 520? and 8h,with the solid solution temperature increases,the primary a phase gradually reduced,secondary a phase precipitation gradually increased,the size becomes smaller,strength increases.When the solution temperature rises to 800? and above,? phase re-nucleation and growth,the strength of the alloy decreases.For Ti5563 cold-rolled tube after direct aging,when the time is fixed,with the aging temperature increases,a precipitation phase content decreased,a phase size increases.The shape changes from small needle-like growth for the thin strip,short rod and even near spherical.When the temperature is fixed,with the increase of time,the strengthening effect of a phase increases with the precipitation increase,then decreases with the growth of a phase,meanwhile,the plasticity increases.Then the aging effect becomes worse,and the strength and plasticity decrease.Compares with Ti5563 hot-rolled tube for cold-rolled tube,the grain of cold-rolled tube is smaller,and the comprehensive mechanical property is more excellent.